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Tutorials of microcontroller 8051, A step by step easy to use self learning rapidex

Thursday, February 10, 2011

Heart rate (beats) Meter with Microcontroller AT89c51 based heartbeat monitor

This is revised version of heart beat monitor using 8051 heart beat monitor located in this blog ob post.
There were some question asked related to this project. So i decided to redesign the project and make some necessary changes in the algorithm to measure the heart pulses per minute. microcontroller based heartbeat monitor with lcd display ir led and ldr based heartbeat monitor with display on computer and microcontroler LCD display.
The heart rate meter is used to measure the heart beats per minute from finger placing between the sensor. The sensor is made of simple photo resistor and LED. The pulses from the circuit are them amplified and converted into TTL logic pulses using comparator Operational Amplifier.
The analog section of the project is same and taken as such from the last post on this project. Student can take the circuit diagram from that post, if it is not clear. However the LCD connection to Microcontroller are changed in this post. As describe earlier this post is written in the response of student questions so the hardware is slightly changed. If you are familiar of electronics and lcd PIN connection, then you will notice there are not major changes. for LCD details like PIN connection and interfacing with microcontroller, you can just read some related post in this blog. Sufficient material is uploaded for the interfacing of LCD with microcontroller.
In this project, we have used one line 16 character LCD, but any other similar LCD can be connected.heart beat monitor (8051based)
Circuit diagram of the heart rate monitor(micro controller based heartbeat monitor ) is shown we can calculate the heart beat with photo resistance

Heart beat monitor circuit with Microcontroller AT89c51, LCD display, heart pulses circuit diagram, microcontroller based heart beat monitor
The code is written in keil C51 compiler. The c code listing for heart rate (beat) monitor is given below.

Download software/ code written for Heart rate (beats) Meter with Microcontroller AT89c51 based heartbeat monitor
Heart rate (beats) Meter with Microcontroller AT89c51 based heartbeat monitor

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  1. Respected Siram not understanding TMOD=0x21 when we are only making use of timer0in mode 1 shoudnt it beTMOD=0b0000 0010also ido not understandif(tick>3500)tick=0;

  2. @ Sarvesh Ghai
    You have asked two questions about the project of Heart Beat Monitor using microcontroller 8051.
    Answer of Q1. TMOD = 0x21, here we are using only timer 0 with mode 1. So, what ever in upper nibble is, it is meaningless, because, you are not using the Timer1. Ofcourse you can write it, TMOD = 0x01; as well.
    Answer of Q2.
    tick > 35000 is used for a reason that, when we are not measuring the heart beats, then there will be no intrupt. But tick will be incrementing on constant rate. So, it will overflow after some times. To avoid this we have included this instruction in program. Reason of slecting the number 3500 for limit of tick is based on formula of calculation the beats per minutes. It is very simple. You try to find the reason by your own. If you feel any problem, ask it.

  3. Respected Sir plz can u also mention my contribution in the revised code.
    I am greatfull to u for ur help and cooperation but my code is still not working on my hardware,I am not getting the ideal heart rate of 72bpm also, i am unable to figure out the logic/formula behind the reason ofslecting the number 3500 for limit of tick formula for calculationthe beats per minutes.

  4. @ Sarvesh Ghai:
    Your contribution is already mention that the revised version of heart rate meter is writen and posted because of interest of some student.
    The code and hardware posted here is tested. It works fine, from 6 bps to more than 255 beats per mintus.
    So there could be some fault in your hardware.
    you can feed logic pulses instead of sensor. by desiging an oscilator of appr. 1.2 Hz. then change the frequency of oscilator and see the results on the LCD display of heart beat monitor. they should be incoming frequency * 60.
    as formula for beats per minuts is bpm = 6000/bt;
    if bt = 3500;
    bpm = 6000/3500 = 1.7
    there is very simple logic that bt should be less that 6000.

  5. hi.if i replace microcontroller AT89c51 with microcontroller 16f877a can or not? then from this should i modify the coding or i can use it witout modify because my place is hard to find microcontroller AT89c51.
    thank you.

  6. @syaz
    No you can not chnage the microcontroller AT89c51 with PIC16f877.
    This code is written for microcontroller AT89c51 or 8051 family. If you are interested in developing the heart rate monitor project using PIC16f877 then i can provide you the code for that also. mean while go through my other blog
    i have uploaded several project on this blog related to pic16f877.
    You can get idea from there and then ask , if you need any further help.

  7. thank you dr rana.actually im doing my project on this.this project is same to measure the heart beats per minute from finger placing between the sensor. The sensor is made of simple photo resistor and LED. but i must use PIC16f877a.that's why i ask you.i will go through your blog.thank you so much.

  8. hello
    I am a final year student and working on a project.

    Intro: I am actually going to work wid a device which gives out analog reading so this analog voltage wil be converted to digital
    so my main aim is to convert ANALOG TO DIGITAL.
    i would like to know how to go about it and what devices i should used..
    which ADC should i go for and what type of controller should i use.
    at the moment i thought of an ADC0808 and 8051 controller which will send the results to many 7 segmnt displays
    could you please help me with my project
    looking forward to your response.
    Thank you

  9. @ruchi garg
    yes you can use adc0808 with microcontroller 8051.

  10. I am designing this circuit for a leakage radiation tester which gives analog reading so this analog reading i will be converting into a digital reading.

    The meter i am talking about is:

  11. @ruchi garg
    You are welcomed for any help in designing the radiation monitor using microcontroller 8051.

  12. Dr Rana,
    I have been going through your blog many times but i am havig difficulties with the circuit design.Do you have a design of a circuit whcih can convert ANALOG VOLTAGE TO DIGITAL READING.
    IF you could please mail me it would be of great help because i am not being able to go further.
    I have four months for this project can you give me a plan how to go about it every month..It would be of atmost help...

    This section should list out the detailed specifications of the various components, measuring devices, software tool box, data sheet references etc
    I would be highly obliged to you if you suggest me with this project..

  13. @ ruchi garg
    An e-mail have been sent you regarding the project.

  14. dr rana..can u give me ur email because i need to discuss something with you..thank you..

  15. @ syaz
    My e-mail id is writen on this blog. any how here is it,
    for live discussion on microcontroller projects or electronics projects for final year projects plz chat with me,

    yahoo chatting ID is

  16. Dear Sir,

    As I am researching on my final year project which has been the "Development of a USB based Microcontroller Development Board",
    I will be very grateful if you could in any way render your most invaluable guidance as it has a strong link with the 8051 microcontroller.

    Thanks in advance.


  17. Hello sir,
    I am doing my project in Embedded Scheduler specifically on time triggered hybrid scheduler,may i get more detailed codings on it.

  18. Greetings,

    Thanks for sharing this link - but unfortunately it seems to be not working? Does anybody here at have a mirror or another source?


  19. hello sir,
    what will be the output of the opamp circuit on CRO.

  20. respected Sir,
    please post or send the detail specifications of components and refering data sheets. especially led and photoresistor specification.

  21. sir please send detailed specifications of components(specially led n photoresistor),measuring devices,software toolbox on my email id
    waiting for your reply eagerly

  22. hello sir,
    i am a third year engg, student and i am doing "heart beat monitor using 8051" as a mini project. i tested the op amp ckt and i got a square wavepulses of different width output when finger was placed between the sensors.Is it correct? if yes i will continue to next step.
    Also i don't know how to burn the hex code into microcontroller i.e, i need the pin connnections of parallel port...please help me sir.
    thank you sir

    1. hey!! did u manage to complete this project successfully?
      can u plz mail me ur reply at

  23. @prajwal
    Yes you are doing right way.
    which programmer you r using?

  24. @rahulpatil121
    These components are general purpose, you can try different LEDs and photodiode pairs found in local market to obtained best result.
    You can even try IR LED and LDR as a pair also.
    If you fail to obtained desired results, write here, i will check it out.
    There is no special components used in this project.

  25. sir i am using the keil c comlplier and i have no idea of how to burn the code into 8051, some say use usb or parallel port. if i use parallel port i don't know what are the pin connection. please help me sir

  26. sir i am using keil c complier and i have no idea of how to burn the code into 8051

  27. sir i am using keil c comlier and i have no idea how to burn the code into 8051, please give me details of this

    thank you

  28. @ prajwal and
    @ Arun
    I don’t know these are two different persons are single with two different names. Any how, both of these students have asked same question.
    It is good to listen that you are using Keil C51 compiler to write the code of the project based on microcontroller 8051.

    For programmer you would have a device named "programmer". The purpose of this device or instrument is to burn the hex file generated from keil c51 into the microcontroller.
    There are many companies who manufactured the programmer for different microcontrollers/ microprocessors EEPROM EROM ROM etc.
    The best option is buy any suitable and locally available programmer which support all well known microcontrollers used today.
    This universal programmer will help you a lot in practical life.
    If you are going to have some cheaper solution then you can build programmer of your own. There are many programmers available on Internet.
    But now you have to think about some basic questions.
    8051 family microcontrollers are manufactured by many well known companies. Some of the 8051 versions support in-circuit programming and some of them don’t.
    You can check it in the data sheet of microcontroller.
    I can give you an example, the 8051 family microcontroller from ATMEL At89c51 don’t support in-circuit programming whereas AT89s51 do support.
    The in-circuit programmers are relatively easy to construct.
    There are some in-circuit programmer which are interfaced with Parallel ports, serial ports and some with USB port.
    Now new computers laptops don’t have parallel ports and serial ports.
    So there are a lot many options for you to select some appropriate programmer to burn hex file into microcontroller. Select some one and then tell me if you have still any difficulty in that. you can give me some reference also, to help you in selecting one.

  29. Respected sir,
    Iam BE(ECE) final year student. currrently we are working on 'wireless heart rate measuring microcontroller based using zigbee communication link'...we are almost completed with sensing circuit.. n will be grateful to u if u guide us or provide us with some info regarding source code in c n how to proceed further..we need to programme microcontroller to calculate bpm.. which is sent wirelessly using zigbee link n the result is displayed on lcd display which is interfaced to zigbee reciever..

    thanking u..

    waiting for ur rply

  30. sir can u mail me the hex code'my id
    thank you sir

  31. hello sir, i have complied the c code and generated the hex file. please send me the hex file you created so that i can verify it.
    also i complied the code using two different version of uvision( 2 & 3) and it generated different hex file why is it like that?

  32. @prajwal
    Instead to have a comparision of hex files generated by different versions of keil compilars or one from me. You should concentrate on coding and implementation of algorithm.
    It is true different versions of same compilars can generate slightly different hex code.
    But it is realy difficult tode-code the hex code back to asm code and then finding errors and extra piece of instructions if any.
    you should check it in actual hardware or proteus isis.

  33. Thanks Dr.Rana, your algorithms are always a great help to me.
    I've wrote a CCS PIC-C code based on your algorithm and it works perfect.
    I just wanna make sure that the sensor circuit works before I get the parts
    the 47nF 47Kohm combination on the positive terminal of the amplifier is a High-Pass filter at 72Hz, right?
    heart beat rate is from 0.5-3.5 Hz, so I'm guessing it wont pass!
    please correct me if I'm wrong
    Thank you

  34. Respected Sir,we have already discussed d code in my previous mails,but i am stillgetting fkuctuations in my measured value of heartbeat,can u plz checkmy hardware(CIRCUIT.jpg atached file).when i checked with multimeterthe o/p of opamp(lm 324), i am getting 2.93(upper value) and 1.4(lowervalue) whereas proper TTL logic requires 5.0 (upper value) and0.0(lower value), i think that thats why random value is being pickedup by tick when interrupt occurs.Sir can u plz tell me what changes ishould make in my hardware to get correct ttl logic (+5 and 0) i also tried to make modifications in my code as under:sbit PULSE=P3^7;unsigned int var=0,overflow_flag=0;void main(){ while(1){send_string("&bt ");lcddata(digit4+0x30);lcddata(digit5+0x30);lcddata(digit6+0x30); }} void timer0(void) interrupt 1 using 0{ // TF0=0;TH0 = 0x3c;TL0 = 0Xb0;TR0=1;if(PULSE==1){overflow_flag++; }count++; if (count == 20){count = 0; if ( minute_count++==10){minute_count=0;var = overflow_flag;overflow_flag=0;FLAG=1;}}} but i am still not getting bt as 72 bpm and am getting pulse 85 and itabruptly rises to 120 ,whereas it should rise slowly with lsd ofatmost 2 sir,plz help me

  35. @ Sarvesh Ghai
    I received your e-mailed and read today. I was on leave and that’s why I am replying with delay (Sorry for that delay).
    I have checked your circuit diagram which is composed of four operational amplifier stages where as mine circuit was designed with only two OP amplifiers. There is designing difference. I can not say any thing about your analog circuit at this stage unless I fabricate it and test it. The analog interfacing circuit provided here was used many students besides me, they don’t complaint in its analog section. Some have problem in algorithm and coding which were coped with discussion. Now at this stage, I can only suggest you to concentrate on better analog interface circuit and use it properly, you can try mine also.
    For testing point of view, the code can be tested on known frequency signal. You can feed 1Hz frequency stable generated from any RC circuit or oscillator or even 555 timers. And then read the result on LCD. It should be 60 Beats per minutes. Then slowly increase the frequency from 1 Hz to 2.0 Hz and check the result. If these are according to calculated values then focus on analog section.

  36. @Badr
    Yes the analog section is correct and working fine. Many students have fabricated this circuit. You try it and if find any problem then discuss it here.
    If you would like to share your project to other students. You can send me ur hardware software and report. i will post those here in this blog.

  37. Hi, I am a final year Electrical Engineering student and i need helphow to communicat microcontroller with database my database containesinformation about student.Microcontroller send a message and thedatabase replay the answer. If you have any idea about this pleas helpme.

  38. @fetle berta
    yes this project is possible and you would have two parts of this project.
    1. Microcontroller based hardware and software
    2. computer, which will contain database and other information stored on harddisk. A program will be required on PC which have two major task.
    -i- database control
    -ii- communication with microcontroller.

    do some work and then discuss if you feel still any problem.

  39. Respected Dr. Rana,

    This is in regard of your Heart Rate Monitor project using AT89C51 :

    There are two C codes for this same projects on your blog . Could you kindly send me the final working C coding and the Hex file to program the microcontroller ?

    Also, if you could please send me the Proteus simulation file of this project, it would be very helpful.

    Please send the above project related files to this same email id :

    All the projects on your blog are very helpful. Thank you for your time.

    Suchitra. R.

  40. @ Suchitra. R.
    yes you are right, there are two different posts on the same project and both have a code or list in c language.
    There are two reasons for this:
    1. the hardware in both project is slightly different
    2. Algorithm to calculate the BPM is different
    I think you have not read the comments section of these posts.
    The comment sections is very helpful and you will find some important questioning and answering related to this project.
    There is also discussion about algorithm.
    this post is latest and final til date, however if you feel any problem then point out, we will see it and update it accordingly.

  41. Hi i need help in research of 8051 microcontrooller. not sure if u can help me..
    i have an assignment to write a report of 3000 words of a product/application that uses 8051 ic or variant.

    the report shud incude

    1)summarry of product/application usage
    2) design methodology (preferably with block diagram explanation)

    i search the web and couldnt find. really hope u can help me beacuse my assignment is going to due on thurs.

  42. Heart beat monitor projectMay 9, 2011 at 12:33 AM

    hello sir,
    i completed the hardware and the software part . but now i m having problems with opamp circuit. the microcontroller circuit works fine .when i give a square wave of 3 hz ,the display on lcd is works fine.
    but when i feed the output of the opamp circuit it shows "out of range". i m using red led and ldr as sensors.
    please help me sir ,i have another 8 days left to submit the project.
    also if u can attach the photos of this project which u did and the photo of the output of the opamp circuit it will be helpful so that i can see how the pulses are coming from opamp output
    thank you

  43. Sir,
    I am completely a newbie in the microcontroller world. I started my journey with the 8051 series. I came by your project which made me delighted and decided that i would like to implement this for the term project of my school.

    1.This code is written for at89c51 microcontroller. but i've a at89c52 of my own. can i use the same code for my at89c52? if yes, then what should i change in the code you given here. if the change in header file would be enough? of any more change is required, then please mention here. i am using Keil C51 compiler Ver.8.12.

    2. the figure attached here seems unclear to me specially the op-amp section. can you please upload a better & clear picture of the same?

    3. Sir, it would be of great help if you kindly mail me the source code .C & .hex-file along with the proteus simulation mail is I will be grateful to you if u do me this small favor.

    thanx a lot for your time, Sir.:)

    (please,ignore my previous comment. it was unintentionally posted with anonymous name)

  44. Dear Sir,

    I need your help regarding the project "Heart rate (beats) Meter with Microcontroller AT89c51"

    I am using the same code you used in the blog. if i weren't wrong, i used the same circuit diagram u've included there. SO far, im at the simulation stage & having several issues with it. they are given below.

    1) 1st of all, the program could not be built with KEIL. i've used ver 8.12. it shows the error:
    "assembling STARTUP.A51...
    ADDRESS: 100000DH
    Program Size: data=9.0 xdata=0 const=0 code=15
    Target not created "

    2) then i switched to RIDE and the program ran & also hex file created. i loaded the hex file in the Proteus simulation.i've used a 1Hz clock instead of the LED & LDR .But the problem is, the LCD output always shows "OUT OF RANGE". it seems that the interrupt is not created & the condition used in the code segment "bt>=7" is not reached. as um very new in microcontroller world, so its very difficult for me to debug it efficiently & that's why i need ur help. Though you are the original coder,I am attaching the .C file i used, the .HEX file & also the Proteus simulation file. Please have them checked & notify me the problem/ error occurred .

    Thanx a lot for reading my mail. Looking forward to hearing from you soon. :)


    1. hey..! did u manage to complete this project successfully? if yes, could u plz mail me at
      i have a few doubts and it would be great if u helped me!
      thanks alot...


  45. @ Shubra
    Hi Shubhra;

    i checked your circuit diagram and code in c language also. you did excelent work by understanding where and why error comes in the compilation time. I want to tell all my student the possible source of error in the program is due to very first statement in the code. Please include reg51.h file in the program according to the need of c51. when i try to put my codes on blogger the include line donot appear properly and student get , the code is not correct instead of find the reason.

    any how you did it in right way thats why you make the hex file.

    Then coming to your question,

    in Proteus simulation, you did a funny mistake, that is

    instead of using actual sensor, you put logic pulses there haaahaaa.

    if you want to check you program then you should the pulser at the input of microcontroller at PIN # 12. because the OP-AMP takes very low level signals from sensor then amplifies it and generate logic pulses accordingly. the microcontroller needs these logic pulses to read the pulse rate.

    Thus for checking purposes one should apply digital logic pulses directly to microcontroller and remove the connection from OP-AMP.

    I have corrected the circuit in the Proteus simulation file and checked, your code and circuit is working fine.

    I am sending you the file, notice the changes and go ahead.

  46. hello sir i completed all the hardware and software part but the problem is i am getting a square wave of frequency 100Hz from pin 7 of the op-amp. if i am correct it should be around 1.2Hz
    hence 'bt' is coming around 2 which does not satify the condition 'bt>=7'. please help me sir,also the frequency remains constant even when different people heart beats are measured .please help me sir ,i have 3 days left to complete my project

  47. hello sir,
    the value of the pots used in analog section in 1kohm and i correct?

  48. @ Arun
    1. The frequency of pulse generated from analog section of the heart rate monitor is about 1.2Hz, so that BPS remain near 70.
    2. If your OP-AMP section give highr pulse rate then this, it need some rectification/ modifications. So, concentrate it and find the cause of errors.
    3. At this stage, i can not tell you, which is the source of error or which component ir required to replace. You have to find it yourself.
    4. The loose connections, or faulty sensors, or faulty OP-AMP may be the possible source. The circuit i presented, works fine.You can go through the comments section as well. Different students faced different problem during developemnt stage and finaly they make it working.
    5. The value of pots should be like that but nearest values can work even better, thats why pots are used. We can adjust the value of pots resistor according to our needs.

  49. Dear Sir,
    Thnx a lot for ur reply and i'm really very happy about that :D. I've informed all of my group mates about your website and they also found it great helpful.
    1) The mistake I made was really silly but I thought that the interrupt should be given via Op-amp to the microcontroller. any way,ur corrected form works fine.Sir, I made a correction to my circuit before getting ur mail and it worked too. I just added a NOT gate after the op-amp and fed it to the MC, no problem of getting output from my previous ckt. i attached my new form too. But, why the LCD shows a abrupt & larger value first whenever the pulse signal is kept from 0.4-1.4 Hz. if thee frequency is kept morethan 1.5 Hz, it shoes the exact value from the first time. 2) My another question is, why the op-amp has not been biased. is it done only for simulation i mean does proteus biases the op-ampautomatically or i don't need to bias it either in real time? i am going to implement the circuit today & thats why its very important frome to know.
    3) Sir, i'm not getting the 11.0592 MHz oscillator in my region andgot 12 MHz instead. as the calculations are based this frequency, insimulation i used 12 MHz & there are big discrepancies in the can i compensate the result for a 12Mhz clock ? Thnx in advance.-Shubhra

  50. @Shubhra
    Thanks for informing others about for my web blog. I like to help students in their work.
    1. the problem for the rang 0.4-1.4 Hz is due algorithm, i make it work with my knowledge and efforts. You should work it to remove this error and give me corrected code so that other can get advantage of it.
    2. The power PINs of OP-AMP and microcontroller are hidden and are automatically baised in Proteus simulation. But in real circuit you should baised accordingly, its your duty.
    3. The calculation are based on 11.0592 MHz oscillator. If you want to use any other oscillator for microcontroller then take care of it. and make neessary chnages accordingly. for you quick help,
    you should change the following line of code;
    TH0 = 0xdc; //The value is taken for Ssc/100 at crystal 11.0592MHz
    this is in void timer0 (void) interrupt 1 using 1 // Timer 0 for one second time .
    the re-load value of "TH0" will need some correction. You can find it by calculation or hit and trail mathod in proteus simulation file.
    if you need further help, ask me. But first do it by yourself.

  51. Shubhra Deb PaulMay 24, 2011 at 6:49 PM

    Sir, I'm experiencing a few problems while implementing it practically. The LCD always shows "out of range". no bpm is counted i think.The output of the opamp (pin#7) is keeping very low, approximatelyfrom -0.08 to -0.03 volt without placing finger. when i place thefinger, the output remains almost fixed around 2.1-2.12 volt.probably, the interrupt is not generated so that the MC can so itscalculation. now what should i do sir ? i'm using two 1k pots. butchanging their value doesn't change the output that much.And another question, how much time someone need to put his fingerbetween the led & ldr ?

  52. @ Shubhra Deb Paul
    The problem is in OP-AMP circuit, your microcontroller code and circuit is working perfectly correct. The interrupt is generated when the signal changed from high state to low state, (falling edge trigger). This problem can not be solved by just checking the voltages on the output pin of OP-AMP section because the square wave signal of any frequency can have 5v (as they wil be changing ov or 5v at some rate which called frequency).There is good sign of changing voltage on this pin by placing finger on sensor and without placing finger. But here question is how much frequency is generated when a finger is placed. Ideal it should be 1.2Hz or near it. If the frequency generated from OP-AMP section is not in suitable range (i.e 0.4 to 1.5 say) then message will be printed "out of range".
    Now there is two check of this.
    1. Disconnect the microcontroller and OP-AMP section. Put an external signal to microcontroller from any stable source (oscillator which can give a signal of 1.2Hz) then results on LCD will be printed approximately 72 Beats per mints. If so then microcontroller section is working properly. If not then you should think about it. You can build a 555 oscillator or function generator can also be used for this.
    2. Now we come on second section testing. Use any frequency meter or oscilloscope to measure the frequency at out put of OP-AMP in both conditions (with and without placing finger in the sensor). Voltage measurement will not help here. OK.
    If you find it not in suitable range then do some modifications in the OP-AMP section to make it working.
    I hope you will find the possible cause of error.

  53. @ Shubhra Deb Paul
    3. If you do not have oscillator or oscilloscope or you can not arrange it. then one quick method to rectify is that play with your code and re-compile it then burn the new HEX file into microcontroller then observe it.

    4. for this at first stage you can remove the if and else.

    change the below code

    bpm = 6000/bt;
    send_string("Pulse. ");
    send_string(" bpm ");
    else {
    send_string("out of range");}

    with this

    send_string("Pulse. ");
    send_string(" bpm ");

    i think this will help you.

  54. hello sir,
    i completed the project and finally got everything working.
    Thank you for your support and guidance i appreciate it.Also if you could tell me some projects which could be done in final year of engineering it would be helpful for me. Thank you once again for everything you have done

  55. Shubhra Deb PaulMay 26, 2011 at 12:00 AM

    I checked the circuit in the oscilloscope today & found that the output signal of the opamp is around 104 hz rectangular pulse of amplitude '5' with finger instead of 1.2 hz even for different persons.

    I could not manage to build a oscillator using 555 timer but i took the output of the function generator, rectified it and then put it as the input of the microcontroller. the lcd shows output but it was not stable. e.g. for 10 hz input it showed bpm of different values as 600, 666, 660, 857 and even sometimes "out of range" at different moments. do u think , it is working still?

    And i also changed the code file as u instructed to do, but it shows "bpm y38" with no finger & "bpm 100" or "bpm N00" when hand or any type of object is placed between the led and ldr.

  56. @ Shubhra Deb Paul
    1. As i indicated the most probably problem may be in the OP-AMP circuit. So your test result shows that it is not working properly. The 104Hz are too much high, it should ne near 1.2Hz for a normal person. So try to rectify the problem. Replace the components which are suspected faulty.

    2. The 10 Hz frequency from function Generator is also high. But response of microcontroller shows that it is working fine.

    3. the results like "bpm y38" or "bpm N00" show that the mathematical calculation are done on overfloe variable which are possibly due to very high frequency input, as the program is not written for higher values.

    4. Plz check and replace if required the sensors too.

    5. What i can say is

    " check the sensors and OP-AMP section" Only.

  57. @ arun,

    Bro, congratz to u that, u made the project into a success:).
    NOw i wanna tell u that,I'm facing the same problem that u faced once i mean i am also getting the output frequency at pin#7 of the op-amp almost 100Hz . i'm ripping off my hair but cannot solve the problem till now. can u help me that, how u've overcome this difficulty. what the values of the pots u have used?
    or have u changed any different components. plz be details.i need ur help.

    thnx in advance :)

  58. Hi sir,

    Thanx a lot for your guidance. I did the same mistake as "shubhra" did in proteus. I am getting "Out of range" in the lcd. So the bt is not greater than 7. I din't understand your reply to shubra a bit. can please tellme clearly sir??

    I am trying this at iit-m, as i got selected for a summer fellowship programme for 2 months. If u guide me in this, it wud help me greatly to work more on this.if i get it right in proteus, i wil try it live.

    Also tell me whether it is possible to use a mic and detect the beat rate? Wil the mic be sensitive enough?

    mail me:

  59. @Dr.Rana,

    Sir and also i gave the pulses directly without opamp as u said in proteus, and i'm just getting "Heart Beat" in lcd, and no values, y is it so??

  60. @ mahesh balan
    It's good; you select this project for your summer project. I hope you will do it.
    The heart beat monitoring project using microcontroller 8051 is nice project to learn the operation of LCD and OP-AMP and interfacing of Transducers with microcontroller. I think you should go through different post available on this blog, these will help you a lot in understanding the basic operations and interface. Please not that, there are two posts on the heart beat monitoring project. One is this, you are currently reading and other is an older version of this, you can find its link through read the text.
    I can not understand your question; so, write it clearly what you want to know.
    The pulses should be less than 2HZ and for better result it should near 1.2HZ.
    Reading the comments from other students will also help you a lot.
    So keep it up.

  61. @Dr.Rana

    Thanx for the response sir, i want to test the circuit in proteus, and on reading the previous comments, i learnt that u hav asked to directly give the pulses to the pin #12 of micro controller without using op-amp in proteus. i tried , but i'm just getting "Heart Beat" in the display and i'm not getting the values as i vary the photo resistance. Give me an empty mail sir, i wil reply u back with my proteus file.


    thanks a lot sir.

  62. @Dr.rana: Sir did u giv me a mail?? I wil reply u back with my proteus file sir.

  63. Read through your Blog --> I got some idea. Thanx a lot for that first.

    Sir i'm very novice to project stuffs and i did this project in the iit-m fellowship programme, planning to finish it in 1 week, so i need a clarification.for designing oscillator circuit:

    so here, we hav 2 unknowns, hw to calculate the l c1 c2 values for 1.2Hz value sir??

    I'm very novice, pls help me out to complete my project sir. Planned to use a colpitts oscillator.

    In this, i attached my proteus circuit and will remove the opamp part once i design the oscillator.


  64. @ Mahesh
    Copy all the keil project files in a folder and proteus files in an other files.
    then zip these folders and send it to me via e-mail.
    the file you sent me did open, it needs some other revent files for proper functioning.

  65. I have attached and mailed u as winrar file sir. Need to replace sensors stuffs by an oscillator. Program is working perfect.

    Thanx a ton,

  66. @ Mahesh
    I have checked the project by replacing the output of the OP_AMP with fixd clock of 1.2Hz for testing of your project.
    It works fine. The file with this change is being sent to you.
    Now you should go ahead, as first phase of project is working fine.

  67. Thanx a lot sir! I will move on with the hardware working of Heart rate meter project using microcontroller 8051.

  68. Sir, i'm unable to get a 16*2 lcd display in my near locality in chennai, is there any other way of proceeding with my project??

  69. @ Mahesh Balan
    You can start your project with any LCD, like 16 * 1 or 16 * 2 or 20 * 1 or 20 * 2 or 24 * 2 or 40 * 2

    any general purpose LCD will work, as we are using only one line (first line) and initial 16 characters, if you get any bigger one, donot worry about it. The remaining scpace will be remianed empty.
    i think you got my point.

  70. oh yeah i got your point, thanx sir, wil try and let u know.

  71. i want to choose this heart rate meter as my final year project (EIE 4th yr). can u plz tell me an approximate cost for making this one??
    Thanking u,
    Saikat Roy.

  72. Respected sir...

    We are students of final year. Recently we have gone through your blog. We found it very helpful for the students.

    we have taken up heart beat monitoring system as our mini project. We need your help regarding

    1) revised circuit diagram of heart beat monitoring system
    2) list of components and their specifications
    3) assembly language code of the same

    We will be grateful for your assistance in this regard.Please do reply as soon as possible.We eagerly await your response.

    thanking you

  73. @ Anusha
    Thanks for visiting my blog.
    Yes, you are right, i used to help students in their miniprojects and as well as in degree projects.
    Students from all over the world find helping materials from and ask questions regarding their projects and find help from me,(if i could , i do).
    the answers of your questions are as under.
    1. the revised circuit diagram of the heart rate monitoring project is uploaded in this post, you can see it. the c language code is also given for students. (this project is done by many students, they find it correct, some of them give me feedback and circuit was updated based on the problems faced by different students, so this is updated versions, although the old version of this project is alos on thisblog, you can find it in old posts, the url is mentioned in this post too.)
    2.the part list is to be developed by urself. it is not a big job, if you can open the circuit diagram on your computer then making a list of componets used in this project is a big job. so do it by urself.
    3. sorry for assembly language the "Heart rate (beats) Meter with Microcontroller AT89c51" i developed is coded in c language using keil C51. it will be time consuming work for me to do in assembly language. i suggest you to do in keil c51 and code is readily working coditions availble.

    if you have further questions plz ask.

  74. Thanks for your prompt reply sir.the circuit diagram in ur blog is a bit unclear.would u plz mail us a better circuit diagram as soon as possible.

  75. @ Anusha
    if you are asking about the analog portion of the circuit diagram of heart beat counter, then plz look at the second post of the project (old version of heart rate monitor), the analog portion is same but the microcontroller side is different for old and new version. This time i donot have the circuit diagram , if u still have any problem then report it. i will see if i could do any thing.

  76. Sir We have few questions about the circuit diagram
    1)What is LDR(photo resistance)?Are there any specifications or? canwe use any LDR there?
    2)What are RV1,RV2 and RV3 in the circuit diagram and how to connectthem in the circuit?
    3)In the analog section,is the 8th pin connected to the 5th pin?alsois the 4th pin connected to RV2 and R3?
    4)In the analog portion,are there any Vcc and ground connections to8th and 4th respectively?if so how much Vcc?
    5)What are the digital logic pulses in the microcontroller part andhow to generate them?
    6)There is a Vcc supply to 31st pin in microcontroller it aregulated supply of 5 volts? Plz clarify the above doubts and plz let us know when u will beavailable for direct chat on your chat account.
    Thank you

  77. @ lakshmi anusha
    The answers of the question for the project of heart bet monitor are as follows:
    1.LDR is photo resistor and any photo resistor can also be used. I suggest, purchase two or more different types and tries, which one gives you better resutls.
    2. The RV1 and RV2 are variable resistors. connect these as shown in circuit diagram.
    3. No these are no connections.
    4. yes, +5V VCC and GND = 0V
    5. The analog section of the circuit will generate the digital logic pulses as output and these ahve to feed microcontroller as input.
    6.Yes, the same powersupply which is required to power up the microcontroller 8051. I think you are very low knowledge of microcontroller and electronics circuits. for your information, VCC is applied to PIN 40 and GND is to PIN 20 of the microcontroller. But for its function from internal memory , PIN 31 is also connected to VCC, actuall it required logic "1". If it is connected to VCC, then microcontroller will search for external memory for program execution.
    I am usually available in evening for chatting.

  78. Hi Dr. Rana,
    It is an awesome project, I want to take it as the final project. Sir can you please send my the related files so that I can constructed this project (including the Proteus). Here is my email address:


  79. @ Fauz,
    yes, the heart beat monitoring project is very popular these days among students.If you want to take it as the final project, it will be good choice. I can not send you files of code, circuit diagram and Proteus files because, it will be bad for you if you get all stuff ready and you donot work for it by your own. Then how will you understand the microcontroller programming and electronics circuits. Thus, i suggest you, to take help from my blog and develop your own idea to make the project. If you feel any difficulty in designing or constructing the project, ask your question, i will help you, as you can see amny students already made this project, and they get help from me.
    for your help, your yahoo id is added in my yahoo chat id, you can contact me for further help on your microcontroller project live.

  80. Greetings Dr.Rana

    I am in the same situation as syaz.
    I am going to use Pic 16f877a in my project.

    I am aware that i need to change something on the proteus diagram.
    Then I believed the coding will be totally different as well.

    Please let me know if my doubt is correct.

  81. @ George:-
    yes, you are right, if you would like to use PIC 16f877 microcontroller in place of 8051 microcontroller in the project of heart beat monitor, then you have to do some changes in hardware and also in software.
    i suggest you that i have a samilar project on an other blog using PIC16f877 microcontroller, although the topic is slightly different but the functionality is same. you can go through it and if you want some help from me, then ask the question.
    Topic of project:-Detection of Anger through BPM Beats Per Minuetus(Heart rate) with MicroController PIC16F877
    URL of the project:- PIC 16f877 micrcontroller project for heart beat monitoring

  82. Hi again Dr. Rana, thanks for your advice. Actually I already done compiling dan simulating your circuit by using Proteus. While simulating with Proteus, I'm using LM016L for the LCD and it running fine. My problem is, LCD display LM016L is not available at my place except for normal LCD 16X2 characters can I use it? so can you advice or guide me on this matter.


  83. @ Fauz,
    If the LCD LM016L is not available, then you can use any generalpurpose LCD of 16 characters and 2 lines or even 20 characters and 2 lines. connections of all general purpose LCDs are same, and this code will work with them. Some students already asked, about it, and then they used the available LCD in loccal market.

  84. Dear Dr. Rana, I just want to ask your opinion, if I replace the pulses from sensor with a push button as switch connected between pin 12 (P3.2) and ground as to test the program, what about that?

    Than after that only I will cater for the sensor circuit, for me the most important thing is the program, for the sensor circuit I might overcome it (I hope).


  85. @ Fauzi,
    Yes , you can connect the switch at the input of microcontroller instead of actual signal for testing. But please note that this code is written with some checks, for proper functioning, if the pulses are too low or too high then reading will not be displayed.
    for your information, normal heart beats are 72 beat per mint (BPM), so external signal should be near 1.2Hz, if you can contineously press the switch with this rate then, its OK. otherwise you can build an external osilator of this frequency for testing.

  86. Hi again Dr.

    I really appreciate your help guide. I already bought LM358N for the sensor circuit, but I wonder it is 8 pins IC instead of both op-amps in one DIP, is it the right IC? because the schematic a bit dim and not so clear.

    The value of RV2 too is not so clear, can you please give it value for me?

    Thanks sir.

  87. @ Fauzi,
    The IC LM358 has two OP-AMP in it and it has four legs (PINs). For PIN configuration you can find its datasheet on internet very easy. The value of variable resistors is 10K ohm. If circuit diagram is not clearly visible, then you can check the circuit diagram on the old version of this project, URL is given in post.

  88. Hi Dr. Rana,

    Here is a video which I put in the YouTube showing the sensor section of my projeck:

    What do you think sir? Does it measured the right beat?


  89. @ Fauzi,
    yes, the setup for heart rate monitor' analog portion is good and i hope it will work.

  90. @Dr.Rana
    sir i have to plan to do project in pic16F877 so i need the schematic diagram and model source code for the mobile message service based heart beat monitoring system...

  91. @ MANI
    i suggest you that i have a samilar project on an other blog using PIC16f877 microcontroller, although the topic is slightly different but the functionality is same (without SMS functionality, LCD is used to display results in BPM). you can go through it and if you want some help from me, then ask the question.
    Topic of project:-Detection of Anger through BPM Beats Per Minuetus(Heart rate) with MicroController PIC16F877
    URL of the project:- PIC 16f877 micrcontroller project for heart beat monitoring

    2. Heart beat monitor PIC16f84 Microcontroller display on LCD

    You can use any of the above project. But you have to some necessary changes in hardware and software to inculde the setup of mobile phone interfacing to get the functionality of SMS, after hear beat monitoring.

  92. Hi sir,

    I have constructed the microcontroller (uC) circuit on the protoboard and have tested it. I got several problems and hope you can help me on these.

    1. Who keeps the time (the periodic of 1 minute), uC or the user? Why sometimes I have been waiting up to 5 minutes still fail to get any reading?

    2. What is the meaning of 'out of range'? and what is the different with 'out of rangepm'?

    3. I found out that, when I turn ON the supply (5V), if the LCD is displayed 'out of rangepm' I still have a chance to get the reading (of bpm) even though the figure is abnormal but if the display shows 'out of range' so definitely I will not get any reading even if I wait until 5 minutes, sir can you please explain why?

    4. Sir I have counted my heart rate beat manually (by using the sensor circuit without connected to uC section), it is around 88 bpm, but when I measured by using this circuit I will get normally around 240 bpm, so what I need to do in order to make it to be accurate?


  93. @ Fauzi ;-
    Its good to hear that you are developing hear beat monitor on some protoboaed. A general instruction in this phase is " please check all the wiring connection of project and there should not be any loose connection". Now answer to your questions:
    1. if you check the algorithm careful, you will notice, we donot need to wait for a whole minute for the result of beats per minute.
    actually the time of each pulse is measured and then converted to frequency and onward to BEATs per MINUTE BPM.
    2. when desired frequency for healthy person BPMs say 70 BPM is 1.2 HZ. so there is a range of frequency feeded in the program ,if the measured frequency is within a rang then converted to BPMs and results is shown otherwise message is prented out of range.
    3.when the monitor is not in use, not fingure is placed between sensor, it will received a contineous logic 1 or logic 0 instead of pulses, so , monitor display "out of range". When properly fingure is placed at sensor, and pulses are started, then after some time it will show reading, and you should keep placing the fingure till the stable response.
    4. repeat your experiment for five time, if problem remains, then check the connections carefully, therewould be some problem in circuit diagram. As far as code is corcern it is tested and i think you have done it on protesus ISIS. if not then test it on Proteus for code varification.

    I have re-checked the code and proteus ISIS simulation for you and never find any five minutes delay in operation.

    if still you feel any problem then ask the question.

  94. @ ALL Students who want to develop heart beat monitor:-

    Please note that the code is written for microcontroller 8051 in c-language taking consideration of crystal 11.0592MHz

    Thus use a crystal 11.0592MHz
    with microcontroller 8051 in the circuit of heart beat monitor.
    other crystal will not give correct BPM values.

  95. Hi again sir,

    Thanks for all the answers.

    I forgot to tell you that, I am using 12Mhz crystal, which I thought it is closed to 11.0592Mhz. Sir is this affected the reading?


  96. @ Fauzi ;-
    11.0592Mhz is required to use in this project, 12MHz will not give correct readings.

  97. Hi again sir,

    I have replaced the crystal but still the result is more or less the same.

    I want to ask you, if let say the output pulse from sensor circuit is around 2V, can it be detected and recognize by pin 12?

    Thanks sir.

  98. @ Fauzi ;-
    The input to microcontroller 8051 at pin # 12 is TTL pulses coming from the OP-AMP section of the heart beat monitor circuit.
    The voltages at the output of OP-AMP can not be used for any troubleshoting because when there is logic high the voltage will be 5V and then after a while there would be logic zero then voltage will goes to zero volt. Thus for square wave pulses the voltages always go from 0 to 5 to 0 to 5. This situation will creat some average voltages if the frequency is stable. The average voltage could be between 0 to 5 anywhere dependig upon the duty cycle and frequency of pulses. So if you have measured 2v when sensor is active by placing a fingure between it. The 2v shows presence of pulses.
    If i took it other way, that 2v are present when circuit is not being used then it is matter of worry and you should check it to fix, because it should be stable logic eithor zero (low or 0v) or one (high 5v).
    The best testing of microcontroller portion is by applying a square wave of frequency approx 1.2Hz to PIN 12 of microcontroller and see the results should be 72BPM. You can obtain the square pulses from any oscilator based on 555 IC or from function generator.
    similarly, the operation of OP-AMP can be tested using an osiloscope to observe its behavore when it is sensing of heart beats through fingure and when it is not being used.

  99. I am implementing heartbeat and temperature monitoring as a final year project
    I need a little help from you
    this is a brief description of my project
    The primary function of this system is to monitor the temperature and Heart Beat of the Patient and the Data collected by the sensors are sent to the Microcontroller. The Microcontroller transmits the data over the air.
    At the receiving end a receiver is used to receive the data and it is decoded and fed to Microcontroller, which is then displayed over the LCD display. If there is a dangerous change in patient's status an alarm is also sounded.
    Apart from this i also want an sms of the information to be sent patient's relative and doctor
    I have the circuitry for heart beat monitor transmitter and receiver
    I want to know what circuitry is to be used to implement the SMS part
    Basic major ICS to be used in this are LM 358
    AM transmitter
    AM Receiver
    16 x 2 LCD

    my email id is
    please help

  100. @ Frazer :-

    It is good to know that you have a nice project proposal for the implementation of heart rate monitor project with temperature monitoring.

    The circuit you already have for the basic functions can be extended for sms sending.
    It is better if you send me e-mail with all the circuits and materials. if you have made some circuit diagrams in proteus ISIS, it is even more nice.
    send me the material you have sofat, then after examin, if would be in position to tell you where the changes are required.
    my email id is given on blog.

  101. sir can you plz give the component list and their values spl. the values of the variable resistor plz mail me this to me my email id is plz asap
    thank you

  102. plz sir do mail me or reply to this comment its urgent

  103. @ UNKNOWN
    To make the list of components is not a big problem or the task one can not perform, if he wish to do a microcontroller project from a available circuit diagram and code by just copying it.
    if you have problem in identifying the value of variable resistor, then for your information it is 10K Ohm.
    i donot know, why students have not not time to read the previous comments.

  104. Respected sir
    can you please give us the description of the circuit diagram of "Heart rate (beats) Meter with Microcontroller AT89c51 based heartbeat monitor"

  105. Hello Dr Rana,My name is Dave,i have been following up ur heartbeat project with keen interest becos my project ues the same algorithm to work (Tachometer which measures the speed of a rotating object in RPM),please Dr Rana,how possible can i modify ur code to measure RPM of up to say 6000RPM or above,thanks for ur anticipated favourable response. Dave

  106. @ Dave :-

    You have posted in comment in the project of heart rate meter but you want to develop a RPM meter.
    Any how, send me the circuit diagram and code you have .
    Then i will check it and modify it into the RPM meter range you told.

  107. @Dr.Rana,sorry for responding late to your reply,here is the codes below,i dont know how to post my schematics. the lcd is connected to Port2 (8bits mode),rs =P3.0,en=P3.1,rw = grounded,heartbeat pulses is on P3.2.xtal freq=11.0592mhz.
    8051 Based Heart Rate Meter Main Program

    #include // using ride 6.1.6 IDE ,Keil also use
    sbit bt =P3^2;

    // unsigned char bt=0,sec=0,sec100=0,min=0,r,t1,t2;

    // unsigned char val[] = {’0′,’1′,’2′,’3′,’4′,’5′,’6′,’7′,’8′,’9′};

    void extrint (void) interrupt 0

    void timer0 (void) interrupt 1 using 1
    TH0 = 0xdc;

    void disp(unsigned char n)

    void main()
    EA = 1;
    TMOD = 0×02;
    IT0 = 1;
    EX0 = 1;
    ET0 = 1;
    TR0 = 1;

    LCD_puts(”Welcome to H.R.M. “);


    / /***********************************************//
    LCD Header File Routines

    #define LCD_clear() LCD_command(0×1) /* Clear display LCD */
    #define LCD_origin() LCD_command(0×2) /* Set to origin LCD */
    #define LCD_row1() LCD_command(0×80) /* Begin at Line 1 */
    #define LCD_row2() LCD_command(0xC0)

    sbit rs = P2^5;
    sbit en = P2^6;

    void lcd_en ()
    en = 1; en = 1; en = 1;
    en = 0; en = 0;
    void LCD_delay(unsigned char ms)
    unsigned char n;
    unsigned int i;
    for (n=0; n
    for (i=0; i<1535; i++); /* For 1 ms */


    void LCD_command(unsigned char command)
    rs=0; rs = 0;
    P0 = command;
    lcd_en ();


    void LCD_init()

    void LCD_putc(unsigned char ascii)
    P0 = ascii;
    lcd_en ();

    void LCD_puts(unsigned char *lcd_string)
    while (*lcd_string)

    once again Dr Rana,thanks for your anticipated favourable reply.

  108. Sir can I get a Complete circuit or a Schematic
    And a Short tutorial on this Project How to begin This.

    Please I m new to electronic Projects.
    Please Help me Out Sir

    Mr.Anonymous, you should post comments with some name, so that, one can know what was asked and what is the reply or whose reply is that.
    The code you updated for heart rate meter is incomplete and why you posted it here, because i donot know the reason or problem with the code or problems in your project unless you tell me the issues in the code.
    If you want to send the project circuit diagram, then use the e-mail for this purpose.
    My e-mail id is ""
    yahoo chatting ID is ""

    You should send following three things to understand the project and identify the problems:
    1. zip all the code files, keil code folder.
    2. zip the proteus project files for circuit diagram if you have not proteus, then , image of photo of circuit daigram.
    3. problems you are facing.

  110. @ ashirwad :-
    What do you mean by complete circuit diagram and complete code??
    The protesus ISIS circuit diagram of project and c-code of project is already uploaded on the post. If you feel it is incomplete, then mention the areas, where you need more information.
    Point out the information specifically , you required.
    I have given e-mail and chating ID, you can discuss it online.

  111. respected sir,
    i m nimesh doshi.i m facing a problem like when a finger is placed in between sensor then i m getting 3.2v at the op of ldr and if finger is not placed then op is coming 1.2v..but at + and - terminal of first opamp i m getting 0.5mv and 0v input according to your circuit,what should be the value of voltage at both the terminals and at pin number 7 also when finger is placed or not..kindly help me as soon as possible sir

  112. respected sir,
    i m nimesh doshi.i m facing a problem like when a finger is placed in between sensor then i m getting 3.2v at the op of ldr and if finger is not placed then op is coming 1.2v..but at + and - terminal of first opamp i m getting 0.5mv and 0v input according to your circuit,what should be the value of voltage at both the terminals and at pin number 7 also when finger is placed or not..kindly help me as soon as possible sir

  113. @ Dr Rana,am Dave,just want to know if u ave received my mail(my c code and protues simulation files)
    tanks for ur response.

  114. @ nimesh doshi :-
    Several students asked the same question. this is not mater of voltage, it is pulses at the ouput stage of operational amplifier and this issues is already discussed above in comments. So plz read them and then ask if still you donot get the required answer.

  115. @ Anonymous or Dave :-
    resend all files

  116. hi. i having problem, when compile the program in keil. many error found can sir help me.

  117. @ remo :-
    The code is tested and compiled in keil c51.
    if you have error during compilation stage then the reason is " header files".
    please include the reg51.h without spaces.
    then it will compile sucessfully.

  118. but, i already put in header files like this #include//plz ad the reg51.h file
    #include//plz ad the string.h file. the error is in void lcdinit(); this error shown HEART.C(10): error C141: syntax error near 'void'. sir also 10 more error please help me sir.

  119. @ remo :-
    ok, i think there is copy and paste problem if you are using the c code from my post. or if you write it your own then how can i know about errors?

    the solution is :-

    zip all the files of your project and send me on this e-mail ID

    i will check and correct them.

  120. thanks for help sir, I already send my code to email.

  121. @ remo :-
    You were told that plz send your project code files zipped in single file, so that the error may be checked and rectified.

    But you sent me ONLY ONE MSWORD2007 file with extension .docx

    It is very strange, i donot know why student did not do what they are asked.

    Plz notic
    during the compilation of any project in keil c51, several files are generated which there due to some specific reason.
    some are configiration, link,object project, hex and c files.

    so in order to check the code work, you should send me all these files as it is in zipped file.

    I donot have MS2007 so, please donot send me files with extension docx ok, i can not open such files.

  122. sorry for that sir. now i sent new want, please check.

  123. @ remo :-
    Ok, I have checked your code project now.
    When i try it to compile, it has 4 errors and 1 warning.
    The results were as below:-
    compiling Heart.c...
    HEART.C(46): warning C206: 'msdelay': missing function-prototype
    HEART.C(46): error C267: 'msdelay': requires ANSI-style prototype
    HEART.C(119): error C202: 'lcdport': undefined identifier
    HEART.C(131): error C202: 'lcdport': undefined identifier
    HEART.C(137): error C231: '_msdelay': redefinition
    Heart.c - 4 Error(s), 1 Warning(s).

    Reason of all above results :-
    There were typing mistake like you have written msdely instead of msdelay in line # 14.
    The second mistake was in line # 4, where you have written lcdportP2 instead of lcdport P2
    Third mistake was that you have not called a function named lcdinit(); in main() , so i added it at line # 46.

    and now every thing is fine and code is compiled. I am sending back to you the corrected version of your code project. Enjoy

  124. @ remo :-
    I have corrected two more things in your Keil c51 project.
    1. In keil c51 toolbar
    Project ....>options for target1, under target tab:-
    you was using clock frequency 24MHz i changed it to 12MHz.
    2. Under output tab, you have not checked the option to generate the HEX file, so i have enable the option to generate the HEX file, because this file is required to burned into the microcontroller using a device named PRogrammer.

  125. thank you for help me sir. the email not get sir.

  126. sir i have question about circuit.
    1. how the IR LED can detect the heart beat.
    2. also to display the heart beat we must use computer as write in blog.
    3. In this IR led transmitter or receiver used?
    4. may sir explain how the circuit function and also component used in this circuit.

  127. @ REMO :-
    1. There is a pair of LED and photodiode used in this circuit. YOu can try a piar of IR transmitter and IR reciver to check the function, most probabaly it should work. As you know the blood is pumped in the vesels by heart at a specific rate. When a spike of bllod comes there is obstacle in the path of light and when the bloods level is down to normal,there is less obstacle in path. This is detected with the help of LED and photo-transistor pair.
    2. You donot need to use computer for display, the LCD, local display is enough.
    3.As told before, eithor use LED with photo-transistor, or LED with photo-diode, or, LED with LDR, OR , use IR transmitter and IR reciver pair, ONE SIDE WILL EMITE and OTHER SIDE WILL RECIEVE THE SIGNAL.
    4. Functionality of which component is not cleared????

    I have again send you the e-mail, i hope you will get it soon.

  128. thank you sir, I get the email and also thank you for explain. sir, what function of component RV(variable resistor) in this circuit?

  129. sir I also want to know the value of RV 2 in circuit?

  130. @ REMO :-

    The function of RV or variable resistor in any circuit is to obtain a variable resistance of our own requirement in the circuit to achieve any typical result.
    The value of the RV2 is 10KOhm.

  131. sir, I facing problem went make simulations in proteus, I have give the pulse, but the result show is correct or not i don't know. Can sir check for me?

  132. respected sir,
    here i m sending u the circuit diagram for
    microcontroller with lcd connection according to my assembly lenguage
    program....kindly verify that this will count heartbeat or not....else
    point out if any error..otherwise send me the perfect code for
    this...i have to submitt either on monday or tuesday dated as
    10,11...only one day is please help me out sir...thank
    uu...the whole connection is mentioned in ckt diag......waiting for ur
    kindly reply....

  133. @ doshi profile :-
    This is too short schedual to develop the code for any microcontroller based project.
    Is your university give you only one day to complete the final year degree project??
    Very strange

  134. @ remo :-

    Where and how you give the pulse??
    It should be train of pulse or clock pulse of frequency 1Hz. Then results should be near 60BPM.

    why you can not say it is correct or not, explain plz.

  135. because i don't know, what the value get. after i use DCLOCK with 1Hz to simulate i get the value bpm 55 and i also set clock type is High-Low-High clock. sir i also have question, i need give VDD and VSS to cicuit? because the circuit given not have VDD and VSS? can i send email to sir check my circuit?

  136. respected sir
    i need to make this project i have to start it but i am not able to understand the components attached in the circuit diagram provided by the site the connections of lcd and microcontroller are understood but bottom components are not understandable.kindly help me sir.please reply me either here or at

  137. @ Remo :-
    It is very strange that you do not know the corect value of BPMs, the heart beat monitor should show.
    It is simple:
    see, if you are feeding it clock pulses of 1 Hz then it means that 1 beat per second. Thus it should show 60 Beats per minutes.
    1 pulse in a second and 60 pulses in mintue, right?

    Now come to the microcontroller, it strongly depends on the crystal frequency.
    If you will use 12MHz crystal frequency to operate the microcontroller then results will be less in number i.e. 55 BPM on 12 MHz.
    The program is written for 11.0592MHz crystal frequency, so when you will use 11.0592MHz crystal with microcontroller it will show exact 60BPM on feeding 1Hz clock pulses to it.

    I think, you are using wrong value of crystal frequency, so you should change it.
    If you are using proteus ISIS, then double click on microcontroller, a new window will be opened. This property setting dialog window.
    Here you will see at fourth number from top " clock frequency" and infront of it, there is a text box to write the clock frequency, here you should write 11.0592MHz and press ok.

    Similarly if you have develop this circuit on PCB and fixed the componenets on PCB, then you have purchase new crystal with frequency 11.0592MHZ and put it at right place by removing the previous 12MHZ crystal.

    The power supply lines in proteus are normally hidden and you donot need to wired them manually.
    The PIN # 40 of 8051 required +5V and PIN # 20 is grounded at 0V.
    In real hardware circuit, the PIN 31 is connected to +5V line.
    A capacitor 0f 10uf and a resistor of 10K ohm connected in series from positve to ground. the capacitor to +5V and resistor to 0V.
    Then the middle pint where resistor and capacitor are tight together connect this pont to PIN 9. This is power ON reset circuit, you can find it any where on Internet commonly used for microcontroller 8051, you will need it, when you will try to construct this project on PCB.
    For this time in proteus, you can work without using this reset circuit.

  138. @ SMITH :-
    if you have read the post carefully, you had noticed that this project had an old version also published in 2009. There were some problem in that version, so i wrote new program and did some changes in this new version.
    I have pointed out that the analog section of project is same in both versions, the only difference is in microcontroller and LCD connections and also in program written in c-language.
    So, if you are feeling difficulty in reading the components of analog section, where operational amplifiers are used, you should see the old version, there it is very cleared. If still you have any problems, then ask.

  139. respected sir,
    i want to ask u that can we use our own self made software on this kit???

  140. @ smith :-
    yes, you can develop your own software, circuit diagram, or anything you want to do.
    This project is uploaded for student to get idea , how they can develop the heart beat monitor. if you want to change any thing or want to write your software, go ahead. and if you feel any difficulty, you can ask for help.

  141. sir thanks a lot sir for help. sir i have question. i already make one basic microcontroller on,another PCB board and this sensor circuit i made in another PCB board so, i need to give VDD and VSS for this sensor circuit. cause in microcontroller i already give VDD pin (40) and VSS pin (20).cause i see the LM358N got pin(8) VDD and pin (4) VSS. please help me sir.

  142. @ REMO :-
    YOu means that you have constructed two PCBs for analog circuit based on operational amplifier lm358 and digital circuit based on microcontroller 8051 and lcd for heart beats monitor and now you are facing problem in power supply. OK ?
    YOu will need a regulated power supply of DC +5V for the operation of these two circuits.
    You should connect the positive line to VDD (8051 microcontroller PIN # 40, 31) and in analog section operational amplifier LM358 PIN # 8.
    Similarly, the 0V line (VSS)of power supply should be connected to 8051 microcontroller pin # 20 and in analog section operational amplifer lm358 PIN # 4.

  143. hello sir,
    could u please mail me a detailed algo of this project.. am having problems understanding the code because of that... plz plz help..
    iv mailed u as well...

  144. @ priyanka (heart beat monitor code algorithm problems) :-

    What kind of problems, you are facing? The algorithm of heart beats monitor is simple. We measure the time period of each pulse in mseconds and then convert it to frequency (pulses per second) then the pulses per seconds are converted into beats per minuts.
    if you have confusions in understanding the code or program written for microcontroller 8051, then you should talk that part and ask relvent question.

  145. Rakshit Muthappa (analog section of heart beat monitor)October 19, 2011 at 10:53 PM

    sir,i am a student in Bangalore.

    i have chosen the heart rate monitor as my mini project.i have problem understanding the analog circuitry part which outputs the voltage pulses to the micro controller .i am hoping u could explain the functions of the components of the analog circuitry. i e how the op amp stages generate the voltage pulses .

  146. @ Rakshit Muthappa (analog section of heart beat monitor) :-
    The analog section of the heart beat monitor is consisting of analog components like operational amplifiers, resistors,capacitors,and LEDs. The basic function of all these components are taught in all universities. If you have not studied the basic electronics and microcontrollers in your course work, then why you are choosing such a project. Otherwise you should now how OP-AMPS are used and what is function of other analog components.
    Any way read some basic electronics book for this purpose.

  147. sbit rw = P3^7
    sir, could u plz explain the usage of this as per ur hadware...

  148. hello sir,
    thanks for the reply..
    sir plz explain to me the following lines frm code:

    wat is the relevance of adding 0x30?

  149. @ priyanka (usage of P3^7 for RW)

    The LCD has a PIN named R/W. This is a data control PIN of LCD and need proper handling to use the LCD. i.e. we can read from LCD or we can write to LCD.
    SO, you should study the datasheet of LCD.
    When we want to write on LCD , normally we put logic 0 on it, and when we want to read ( or simple not writting any thing on LCD), we Put logic one (high stat ) on this pin of LCD, all this controlling signal is achived through the use of THis pin P3^7 named rw in software. i think it is cleared now?

  150. @ priyanka (convert three digit decimal value into three characters format):-
    Here in this code part, we are seperating the three digits of three digit value and then adding 48 decimal (0x30 in hexadecimal = 48 base 10) as ox30 is ACHII code for "0" and then ACHII code of each digit is send to LCD for printing purposes.

  151. Where is the LDR in the analog circuit?

  152. @ Anonymous ( not finding LDR)
    Try to find, where it should be,

    I think it should be at the input stage of first OP-AMP. WHat you think?

  153. Hello Dr. Rana
    I am a final year student of electrical and electronics technology. i chose the heart beat monitor as my final project. I have few questions about the circuit diagram that you provided on your website. Ques 1: which op amp did you use? ques2: some of the inductor values are not clear. is it possible if u can send me the multisim file of the circuit diagram? if so, that would be great if not can you clarify my confusions.
    Thank You.
    Veerinder Sidhu.

  154. @ Veerinder Sidhu :-
    Answer to your all queston is very simple.
    Try to read he commnts of other students and then my answers.
    Many thing including your questions has been discussed.

  155. Hey Mr. Rana. I have a question. Why did u use older chip in the newer project as compare to the older project where the hardware was newer. Whts the difference?

  156. @ Veerinder Sidhu :-
    Clearly discuss your confusion regarding the chip selection in circuit diagram.
    And this should be your concern that why i am using older chips in new circuit.

  157. Good day to you sir ! I am a new student and not familiar at all with the components, may i ask, what is the components connected to the lm 358 ? thank you for your help !

  158. @ Anonymous (components connected to OP_AMP LM358):-
    Oh, so can not identify the very basic electronics componenets like resistance or capacitors,LEDs,Diode??. Then i think you should read/ study the basic electronics books/ courses and then come on this projects.

  159. hello sir
    i have one doubt. we need to place our finger b/w led and ldr. but which led's light cross our bone and reach other end?? and even if it does wont the difference (light transmitted wen blood pumped out - light transmitted wen blood is pumpe in ) be very small to be noticed ??

    please suggest me which leds to be used? and will IRled BE BETTER OPTION??

  160. @ aasmi:
    do R&D and find it yourself

  161. Hello Sir,
    Please tell me the code for sending the heart rate to another place and reciving it via Microcontroller?

    thank you

  162. @ ANNU :
    Your question is not complete.
    Where you want to send the data?
    Which protocol of communication you are using?
    Is it serial RS232, RS485, EtherNet communication or Wireless??

  163. hello sir
    i asked you earlier also how will led-ldr work fr counting number of heart pulses ? can you please send me a photograph of its actual implementation....i still cant materialise how will led's light pass through our bone ?? and if we place both led and ldr on same side and see light's reflection on ldr den dats also nt possible as bone is nt a gud reflector?? help me to materialise the idea

  164. respected sir
    i have completed the hardware and have also burnt the hex file of the code you have provided but nothing is being displayed on the lcd .kindly tell me what should i do as i have to submit the project on 6th december..i have connected lcd to port2 of microcontroller..

  165. respected sir
    kindly please tell me how led and ldr is able to generate pulses and how op-amp is working in the analog part..i have used lm358p op-amp..kindly reply sir..

  166. @ Smith :-
    Send me the all project files including code in c and other project files of keil c51 zipped. Also send me your circuit diagram build in proteus isis in zipped format.
    After that i will check your code and tell you where is problem.
    The working of OP-AMP and LED LDR is very easy, if you donot know that how basic components do work, then why you are using them, first you should read/ study their functionality.

  167. Hello sir. I'm doing HeartBeat project using 8086 but still have problem with coding to interface 8086 with LCD. Maybe you can help me.

  168. @ IRmasha (Heart beat with 8086):-
    This project i uploaded uses 8051 microcontroller and you are using different processor for it.
    so send me the circuit daigram and code you written, so that i can check where the problem is.

  169. hi sir,iam rajesh.iam doing my mini project on heart beat sensor.the code provided here needs reg.51h and also string header file.from where can i get them sir,plz kindly respond sir.if possible email the circuit diagram and corrected c code with header files to my mail sir,plz.i n my frns will b thankful to u.(

  170. hello sir i m diploma 2nd year student and i made this project but i m using 89v51rd2 instead of 89c51 will it work pls email me to my id pls sir as soon as possible

  171. hello sir i m diploma 2nd year student and i made this project but i m using 89v51rd2 instead of 89c51 will it work pls email me to my id pls sir as soon as possible

  172. hello sir i m diploma 2nd year student and i made this project but i m using 89v51rd2 instead of 89c51 will it work pls email me to my id pls sir as soon as possible

  173. sir, i am final year student.i want to do my final year project.i want ur help.plz sent any good project with all the details and circuit diagram in my e-mail
    thank u

  174. Sir,

    My name is nava and I am a final year student of Beng Electrical and Electronic.I would like to ask your help in order to check whether there is any problem with my circuit diagram and my programming code since i have modified the project on my own.In hardware side, it works fine but i could not simulate it on the proteus and i suspect that there might be problem on the circuit that i may have overlooked.If there is no problems,then only i can do etching process.

    I have sent the related info to your email @ reply asap.

    Thank you.

  175. Can anyone explain that whats the use of TH0=0xdc.

  176. actually the logic is tick is incremented at each 100msec if the external interrupt is high,right?? and sampling rate is 1sec.
    so maximum value of tick will be 10.
    Then how will we get a pulse of 60 (bpm=frequency*60)? that means frequency should be 1 by(freq=(1/tick)*100) or tick should be 100. I am confused. can u clear it.

  177. Sir i want to know the components list as it is not clearly visible in the circuit and is the code given here is enough for the circuit to be a success ? please help me soon... I need to submit this project in 3 days.

  178. sir i want to know the components list as it is not clearly visible in the diagram and is the code given here is enough for d circuit to be a success? pls help me soon sir.. i need to submit this project in 3 days ..

  179. Sir, My name is Akash Third Year Student of E&TC
    My project is 89c51 based heart beat monitoring so i was read your i have a doubt for how this pulses are count. LDR is used to sence the light from LED and finger is obstacle between this two.but i have dout it acually give us reading satisfactory. can we use Photo transister replaces LDR. and suppose we consider LDR is used when doing this project on PCB environment light will generate interferance between LDR and LED. the pulse reading is wrong by environment light. so how we will make this project.
    Thank you.

  180. sir,i want working details for heart beat meter.plz help me as soon as possible.

  181. sir , im very greatfull for ur post, sir but i m not to able to make out the components used in the analog section , the picture is not clear so i request u to plz send the proper circuit and its components so that i can go ahead with dis project my email id thank you ......

  182. pls can u send in brief what does the main logic do?lcddata((bpm/100)+0x30);
    send_string(" bpm ");

  183. can u send the design of the circuit diagram of heart beat counter using 8051

  184. sir,i want to interface lm 35 to 8051 through adc 0808 ,i dont know exact coonection,can you help me?

  185. sir can u please help me with that 3500 thing.i did not understand it.

  186. Hello Sir,

    I am facing problem with the hardware part. I am using LDR & High Density LED. But still not getting the output. It is continuously showing Out of Range. Can u Help me.

  187. @ AB
    and all above students who wants help in microcontroller projects.

    Please send me a detailed e-mail about your projects and problems
    my e-mail ID is


  188. can i do this same project using PIC24HJ64GP502

  189. It is out of range because the system is not detecting no pulse. You can used a function generator to detect the pulse

  190. Hello Sir do i need and ADC to convert analog pulse to digital out pulse

  191. sir can you send me pic file of the circuit supported by isis 6 proteus.

  192. can anyone send me the proteus file at my id

  193. Respected sir i have never studied about microprocessor. Our university has kept workshop on microprocessor in sem 5 and we r going to study this subject now.Is this project posted by u is a easy one??? Will i be able to get output for this project. Sir even i dont no hoe to combine code and hardware. Sir will u please guide me?? My email id is

  194. Respected sir i hav never studied about microprocessor. Our university has kept workshop on microprocessor in sem 5 and we r going to study this subject now.Is this project posted by u is a easy one??? Will i be able to get output for this project. Sir even i dont no hoe to combine code and hardware. Sir will u please guide me?? My email id is

  195. Sir i am successfully completed the coding section but i am getting "OUT OF RANGE" at the output of lcd please help me out thanks in advance..

  196. Looking for Assembly code for this project can any one send me on my ID

    Neha Fahad

  197. Hello sir thanks for the great work! am working on the same project and am left with four months! help me more about the heart rate sensor design because i have been using an normal LDR and one RED LED as a light source to the LDR and another BLUE LED as heart rate status indicator. When i place the finger in between the LDR and LED , the other LED just gets off yet i wanted it to blink according to the heart rate. so i need help on the sensor using MSP430G2231 microcontroller.


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Electric power controller with TRIAC circuit (1) Electronic Humidity (1) Elevator Lift control for three stories with microcontroller 8051 (1) Embedded C (1) Enable signal for row 0 and 1 (1stcontroller) (1) Enable signal for row 2 and 3 (2ndcontroller) (1) Engineering (1) Establishing Serial Link (1) Eurofighter Typhoon (1) FPGA I2C (1) Fluid Level Detector (1) Free 8051 Microcontroller projects (1) Frequency meter (1) Fully static operation (1) Functional Description (1) GSM Modem (1) GSM based Home security system using microcontroller 8051 (1) GSM modem interfacing with microcontroller 8051 for SMS control of industrial equipments (1) GSM/ EDGE Modem in PCI Interface (1) Gadget Renesas (1) Gates (1) Graphic LCD JHD12864J (1) Graphic LCD T6963C (1) Hardware Aspects of Moving Message Display Project (1) Hardware and Software of Automatic Thermal Furnace Controller (1) Hardware specification (1) Heart rate (beats) Meter with Microcontroller AT89c51 (1) Heart rate meter (1) High Temperature Humidity (1) Home Humidity Sensor (1) Home Theater Remote Control (1) How to write Data on LCD (1) Humidity Display and Humidity Transducer sensor (1) Humidity Sensing (1) Humidity Sensor (1) INCREMENT/DECREMENT ROUTINE for motor in assembly language (1) INTR (end of conversion) (1) INTRODUCTION of Automatic Controlled Furnace (1) IRED (1) ISo image file (1) Image burner (1) Implementation Details of Humidity sensing project (1) Industrial Humidity Sensor (1) Industrial valves controller (1) InfraRed Sensor Interface (1) Infrared emitting diode (1) Input Ouput Ports of Microcontroller 8051 (1) Instruction set of liquid crystal display (1) Instrumentation and Data Acquisition (1) Integral linearity (1) Intel’s 8-bit MCS-51 Family of Microcontrollers (1) Interface Humidity Sensor with 8051 Microcontroller (AT89C1) (1) Interface of 4 line LCD with 8051 (1) Interface of mobile phone with micro-controller (1) Interfacing large load bank with Microcontroller 8051 port expander (1) Interfacing of DAC0800 with Microcontroller 8051 (1) Interfacing the ADC0804 to the AT89C51 (1) Interfacing with the LM35 (Temperature Sensor) (1) Internal Ram Organization of 8052 Microcontroller (1) Interpreting on Emulator using Pro51 (1) Interrupts (1) Introduction of The Automatic Car Parking using 8051 (1) Introduction of moving message display MMD using 8051 (1) Introduction serial Port RS-232 (1) Introduction to 89C51 Microcontroller (1) Keil C51 program for interface of Graphic LCd with micro-controller (1) Keypad 7-Segment LED interface with Microcontroller 8051 (1) LCD (1) LCD MMD (1) LCD interface to MCU (1) LCD interface with micro-controller 8051 (1) LCD interfacing with Microcontroller 8051 (1) LCD moving message display (1) LED Display driver (1) LED Grow Light Technology is Much Improved (1) LED display (1) LED matrix (1) LM324 (1) LM35 (1) LPT3 (1) LSI displays alphanumeric characters (1) LVDT (1) Lighting Controls (1) Line PrinTer (LPT) devices (1) Liquid Crystal Display LCD Introduction (1) MAX 232 Interfacing with Microcontroller 8052 (1) MAX 232 level converter (1) MAX 232 serial communication (1) MCS-51 family microcontrollers (1) MCU-PC-serial-interface (1) MOVING MESSAGE DISPLAY USING ATMEL 89C51 (1) MSp430 I2c (1) Mechanical methods (1) Memory of 8051 (1) Memory Model (1) Memory Organization (1) Memory mapping (1) Microchip PIC (1) Microcontroller 8051 Projects in c language (1) Microcontroller 8051 and adc (1) Microcontroller 89c52 (1) Microcontroller Applications (1) Microcontroller Circuits (1) Microcontroller Interface with PC parallel port (1) Microcontroller Port2 (1) Microcontroller data logger (1) Microcontroller to LCD (1) Microcontroller51 MCu 8051 LED interface (1) Microprocessor-Compatible (1) MixZing Music Player (1) Mode Selection (1) Modern DAC (1) Moisture Sensors Devices (1) Motor speed control circuits and projects (1) Moving Message Display (1) Multiplex 74ls138 74ls04 8051 16f877 (1) Multiplex LED seven segment diaplay with microcontroller interfacing 74ls138 74ls04 8051 16f877 (1) NAND (1) NOP in 8051 (1) NOR (1) NPN transistor (1) Non-insulated SCR (1) Nyquist A/D converters (1) Nyquist sampling criterion (1) OJ0800 DAC (1) ON-CHIP SERIAL PORT (1) OPAMP LM324 (1) Objective of the project based on microcontroller 8051 (1) On-Chip Clock Generator (1) Open (1) Operational Amplifier (1) Optical Sensor Subroutine (1) Optical sensor (1) Optocoupler and diac MOC3041 (1) PC (1) PC parallel port (1) PC side program for interfacing (1) PCM codec ICs or DSP interface ICs (1) PERIPHERAL INTERFACE PROJECT OF PRESSURE MONITORING (1) PGAs (1) PIC I2C (1) PROGRAM MEMORY (1) PWM with microcontroller 8051 for SCR or triac power control (1) Peripherals Keypad (1) Philips PDS51 development board (1) Pin assignment of liquid crystal display (1) Potentiometric (1) Potentiometric transducer (1) Pressure Sensing System (1) Pressure gauges and switches (1) Pressure monitoring with microcontroller 8051 (1) Pressure sensing and controlling (1) Pressure sensor and transducer (1) Printer Port's addresses in the BIOS Data Area (1) Program counter address (1) Programmable Gain Amplifiers (1) Programming Aspects (1) Programming Aspects of Moving message display project using 8051assembly language program for lcd (1) Project Description (1) Properties of graphite (1) Pseudo-Absolute Encoder (1) RAM of MCU (1) RAM of microcontroller (1) ROM-to-RAM ratio (1) RS-232 Level Converter (1) RS-232 Level Converters (1) RS-232 Standard (1) RS-232 communication (1) RS-232 serial communication (1) RS232 with 8051 (1) RS232 and Microcontroller 80s52 (1) RS232 and microcontroller schematics and C code (1) RS232 communication (1) RS232 serial communication (1) Receive Data (1) Receive Interrupt of 8051 (1) Register Banks of 8052 Microcontroller (1) Relative Humidity Project (1) Reluctive (1) Remote apps for PC and Mac (1) Remotely view (1) Resonant Wire (1) Routine interfacing LCD with 8051 Programmer's Corner. (1) Rs-232 smoke analyzer (1) SAKURA BOARD (1) SBUF and SCON (1) SBUF register (1) SCR control (1) SERIAL PORT REGISTERS (1) SMS Based Controlling Machines Using GSM Mobile and microcontroller 8051 (1) SN7447 (1) SN7447AN decoder (1) SN74LS373 Latch with 3-State Outputs and interface with microcontroller (1) Schematic Circuit Diagram Speedometer Accurate measurement of speed (1) Science/Research (1) Scratchpad Registers (1) Security Camera Systems (1) Selection of Humidity sensor or transducer or transmitter (1) Sensor (1) Sensors (1) Serial Communication (1) Serial Communication RS-232 (1) Serial Communication microcontroller to PC (1) Serial Interfacing of Microcontroller 8051 in Automatic Car Parking Project (1) Serial or Parallel (1) Servo Actuator and DC Motor. (1) Setting the Serial Port Baud Rate (1) Seven (1) Seven Segment Displays of Pressure Monitoring Project (1) Seven Segment Subroutine (1) Signal control on ADC0804 (1) Silicon Serial Number (1) Smartphone (1) Software Download (1) Software Freuency meter and pulse width measurement (1) Software writting procedures serial port communication (1) Solenoid Valve (1) Solenoid Valve Control System Using 8051 Microcontroller (1) Solenoid Valve Controls (1) Solenoid Valve Supplier (1) Start your car remotely (1) Static Power Switches (1) Stepper Motor Control System Interfaced with Personal Computer (1) Stepper Motor Control System Interfaced with Personal Computer serial port baud rate (1) Stepper Motor Subroutine (1) Stepper motor control in assembly lanuage (1) Strain Gage (1) Strobed Input (1) Supply Check Valves (1) Supporting AT commands (1) Synchronous Serial Communication (1) TEMPERATURE CONTROLLER (1) TEXT display (1) TIMER CONTROL (1) TRIAC control circuits (1) TTL (1) TTL CMOS logic level (1) TTL Compatible Inputs and Outputs (1) Temperature Controls (1) Temperature and Humidity Data Logger (1) Temperature sensors (1) Testing Circuit humidity sensing project (1) The Interface of ADC0804 with microcontroller 8051 (1) The MICROCONTROLLERS (1) The interface of DS17885 with at89c51 (1) Timer and counters circuits (1) Timer and counters of 8051 (1) Timer/counters (1) Transducer Types (1) Transmit Data (1) Two types of connectors are used for RS232 communication (1) U shaped tubes (1) UP and Down counter (1) USB programmer of microcontroller (1) Ultimate PC Remote Control (1) UltralISO (1) Understanding 8051 (1) Universal Blue Tooth controller software (1) Universal PC remote control from your phone or tabletRemotely browse your (1) Use of MICROCONTROLLER in Pressure Monitoring Project (1) VB6 RS-232 serial communication example program with microcontroller 8051 or PIC or AVR (1) VB6 serial interface (1) VLC (1) Von Neuman architecture (1) WDTV Media Players Remote app (1) WIN-Remote (1) Waveform Digitizer Capturing (1) Weather AnemometerRoom HumidityHome HumidityHumidity Cabinet (1) What are the time trigger applications (1) What is null modem cable (1) Wi-Fi Based Home Automation System (1) Wifi (1) Windows Media Player (1) Windows PC over Wi-Fi or Bluetooth (1) Windows Phone 8 and BlackBerry (1) Wireless Humidity Sensor (1) Wireless sensor based Vehicle central Lock Control System using Microcontroller (1) XBMC (1) XOR (1) ZERO-CROSS OPTOISOLATER TRIAC DRIVER OUTPUT MOC3041 (1) Zero crossing Optocoupler MOC3041 (1) access control car (1) accuracy of adc (1) addresses in hexadecimal are 378h (1) algorithm for pulse width measurements (1) alphanumaric LCD (1) analog input voltage to the ADC (1) analog temperature sensor (1) analog to digital conversion (1) analog voltage signal generation of 0 to 10V (1) analog-to-digital converter (ADC) (1) and 37Ah (1) and DS1685 PC real-time clocks (1) and Storing (1) android gmote server linux (1) android market (1) android remote (1) anode (1) apps for special education (1) assembly code circuits (1) assembly code projects (1) assigned devices LPT1 (1) aston martin (1) at89c51 as counter (1) atmel 2051 (1) atmel humidity Assembly Language code (1) atmel serial eeprom (1) autocop car security system (1) automatic car parking system using microcontroller (1) automatic car parking system with microcontroller (1) automatic control systems (1) avr i2c (1) best wireless camera security system (1) better resolution (1) bigger LCD (1) biomedical instrumentation (1) blocked motor start rotating (1) blue control modern (1) board development and fabrication (1) brown out detector (1) build simple calculator using keypad (1) buzzer siron (1) byte read (1) c language code (1) c language program (1) c++ code (1) calibration of ADC and DACs (1) capacitive (1) car parking and microcontroller (1) carbon dioxide (1) carbon monoxide (1) characteristics of analog sensor (1) charging the battery (1) circuit design for a elevator (1) circuit diagram (1) circuit diagram for intestinal sound detector (1) circuit diagram multiplex led (1) circuit diagram of moving message display (1) circuit diagram of serial communication via rs232 (1) circuit diagram of the microcontroller project for humidity and clocking (1) circuit diagram to interface LCD with Microcontroller 8051 (1) circuit disgram of stepper motor (1) circuit prototyping (1) clock vis (1) clocked out (1) code (1) code for gsm modem interfacing with p89v51rd2 microcontroller (1) code for microcontroller (1) commands of lcs (1) comminication (1) common (1) common 8N1 format (1) communicating direct with the aircraft computer (1) communication of the data between PC and RAM. 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