The heart of the circuit is the HM2007 speech recognition integrated circuit. The chip provides the options of recognizing either forty .96 second words or twenty 1.92 second words. This circuit allows the user to choose either the .96 second word length (40 word vocabulary) or the 1.92 second word length (20 word vocabulary). For memory the circuit uses an 8K X 8 static RAM.

The chip has two operational modes; manual mode and CPU mode. The CPU mode is designed to allow the chip to work under a host computer. This is an attractive approach to speech recognition for computers because the speech recognition chip operates as a co-processor to the main CPU. The jobs of listening and recognition doesn’t occupy any of the computer’s CPU time. When the HM2007 recognizes a command it can signal an interrupt to the host CPU and then relay the command code. The HM2007 chip can be cascaded to provide a larger word recognition library.

Speech recognition is classified into two categories, speaker dependent and speaker independent. Speaker dependent systems are trained by the individual who will be using the system. These systems are capable of achieving a high command count and better than 95% accuracy for word recognition. The drawback to this approach is that the system only responds accurately only to the individual who trained the system. This is the most common approach employed in software for personal computers.

Speaker independent is a system trained to respond to a word regardless of who speaks. Therefore the system must respond to a large variety of speech patterns, inflections and enunciation’s of the target word. The command word count is usually lower than the speaker dependent however high accuracy can still be maintain within processing limits. Industrial requirements more often need speaker independent voice systems, such as the AT&T system used in the telephone systems.

Voice Training 

To train the circuit, begin by pressing the word number you want to train on the keypad. The circuit can be trained to recognize up to 40 words. Use any numbers between 01 and 40. For example press the number “01” to train word number 1. When you enter  the number(s) on the keypad the LED connected with the READY pin will turn off. The number is displayed on the digital display. Next press the “#” key for train. When the “#”(TRN) key is pressed it signals the chip to listen for a training word and the  LED will turns back on. Now speak the word you want the circuit to recognize into the microphone clearly. The LED should blink off momentarily; this is a signal that the word has been accepted. Note that The HM2007 can hear words only when the speech indicator LED is on.

Continue training new words in the circuit using the procedure outlined above. Press the “02” key then “#” key to train the second word and so on. The circuit will accept up to forty words. You do not have to enter 40 words into memory to use the circuit. If you want you can use as many word spaces as you want.

Voice Training Steps

  1. Power ON(The LED connected to READY pin will be ON)
  2. Clear Memory
    • Press the digit “9” twice..i.e “99” 
    • Press ‘*” (CLR) Button  (Now the memory is completely cleared)

  3. Press the Memory Location where you want to say your first word

          eg: If you want to save the word “Forward” in the memory location 01, then

  • Press digit ‘0’ followed by digit ‘1’ (Now the LED connected to READY pin will automaticaly turn OFF)
  • Press ‘#’ (TRN) key (Now the LED connected to READY pin will turn back to ON state)


    4.  Speak the word you want the circuit to recognize into the microphone clearly.(The LED will mometarly blink if HM2007 accepts the word. Repeat the steps for saving more number of words).

 Voice Recognition

After training the chip, recognition mode is set and successive speech is compared to the trained patterns for a match. If no match is found, 77 is displayed. When aword is detected, its ID (the corresponding memory location where it is saved) is displayed. In the recognition mode HM2007 will be continually listening. Repeat a trained word into the microphone. If the word uttered mathes with the word saved in any of the memory locations, then the  8 bit memory location will be displayed on the digital display. For instance if the word “Forward” was trained as word number 01, Saying the word “Forward” into the microphone will cause the number 01to be displayed.



Error Codes:

The chip provides the following error codes:

55 = word too long
66 = word too short
77 = word no match


45 Responses to “VOICE RECOGNITION”

  1. aditya Says:

    it is very helpful.

  2. sonal seth Says:

    i want to know about this amazing project

  3. Sean Owen Says:

    Hey, I hope that someone checks this soon, but I really need to get a HM2007 and cant seem to find them anywhere. I am calling the last known manufacturer tomorrow but if someone could tell me what site to order it on or who to get ahold of to get it I would be very grateful.

  4. pranav Says:

    i am doing same kind of project and i need that HM2007 IC ..will u please tell me that where can i get it in india(maharashtra) ? its urgent please reply..

  5. khagendra Says:

    hi…i m not getting the assembly code for interfacing of pic controller used wd motor and the voice recognition ic hm2007…plz tell me where i will get this code…

  6. primo Says:

    Where can I buy the HM2007 chip here in the philippines?
    Can you tell me also because i really really need it for my final project…
    Please reply As Soon As Possible…..

  7. techtriks Says:

    Hi Primo,
    I have no clue on the availability of HM2007 in philippines, However i feel you can order it through net…

  8. rishi Says:

    great job friend, i would like to do this project as my main in engineering

  9. kandarp Says:

    hey ,

    i have that circuit with hm2007 but it is not properly working.
    it recognize my speech and also recognize another people’s speech so it is malfunctioning happen.

    any one have solution

    • techtriks Says:


      HM2007 can be operated in two different modes- One is word dependent(Pls read the datasheet well,…What i am writing is from my memory) other is single person’s voice dependent. .. By default i think u might be t\using the first mode..when the chip is operated in this mode, it will identify only the words you have recorded earlier, not a distinct person’s voice. So for eg. If you have recorded “start”..During the play back mode it will detect the sound “start” only. i.e. it will identify “start” from any person…not necessarily be from the same person whose voice is recorded earlier..

      what we have found is the second mode also is not very perfect and its a bit more difficult to implement

      Best of luck,

  10. shar Says:


    i have a few doubts can anyone help me out..
    1) i heard it is not possible to interface hm2007 to computer. is it true? if not, how to interface it?
    2) our project will need to take the output number displayed on the lcd as the input to our programs “condition statement”, is this possible?

    any solutions or suggestions? pl help me out..

    • techtriks Says:

      Hi shar,
      1) I think if parellel port is available in the computer it is possible to interface HM2007 with the computer.
      2) Its possible to read the 8bit output of HM 2007 and use it for decision making in the program.

      All the best,

  11. varun teja Says:

    helo sir i am interfacing hm2007 ic with robot ,when i say other words which are not stored it is showing to 66,77 like that…
    when i operate it to robot due to motor noises 66,77,are appearing and the robot stop moving,,can i get any solution for this,….

  12. Salman Says:

    hello sir , i want to know how do you switch from training mode to recognoition mode on hm2007
    secondly on 74LS373 do i have to put leds on its output to see the memory location?
    plz reply

  13. techtriks Says:

    Sorry for the delayed reply…hope u might have already tackled the issue… please let me know if u r still struggling on the same…

    alll the Best..

  14. Robert A Brede Says:

    where in the U.S. can I purchase the the hm2007 already assembled & including the keypad

  15. techtriks Says:

    Hi Robert,

    I have no idea about the availability of HM2007 in US. At that time we have ordered through some online US store only.. Please check in the internet…

    Best wishes,

  16. Atul Says:


    I am doing a project on Voice Recognition. Problem is that when I am switching on the supply the LED is not glowing and also the 7 segment display is not showing “00”. Please suggest me some thing so that I can go forward.

  17. what is the microphone configuration u used…i am not able to train hm2007..the ready led is not blinking…its urgent

  18. kunal patil Says:


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  21. Gani rawshid Says:

    Plz i need d circuit diagram of the I.C hm2007 interfaced with a keypad, a display, a microphone and a microcontroller. Pls is the output command msg an analog/digital? I do not if the code can be included.

  22. Desire Says:

    This amazing project is good and we need.the diagram to download as image

  23. Says:

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  24. Roshni Gupta Says:

    i m final year engg. student and interested in doing this please give me some idea about how to strt this project and its list of component and the programming part.

  25. vishal Says:

    i hv doubt if i m siting on chair and my friend says FORWARD is it chair runnung or not?? is it work in noisy places??if i m sitting on chair and i want to talk with my frnd suddenly i m say left/right so it is possible??? plz plz rply………….also give battery and motor specification of wheelchair

  26. parinay Says:

    i need block diagram of the project

  27. kavya Says:

    Hey ,
    my team has decided to work on voice controlled wheel chair .. and we need some suggestions on where we can find the hm2007 kit in and around mangalore ,karnataka.
    thank you .
    you can contact me :

  28. Akash Darak Says:

    can i plz get the program code of this project..?
    its urgent..thank yu..!

  29. ritesh Says:

    i m working on this project …..

    but the problem is that when ever the voice recognize kit found any noise other then recorded command it generates error code but problem is that when noise is removed it automatically go to command one which is recorded it does not continues the command which whose running………..

    plz… if any one knows solution plz help me…

  30. Ajay Verma Says:

    Whenever i want to train the hm2007 kit…as soon as i speak the circuit get struck n circuit stops working….plz tell me what to do…

    Plz..reply as soon as possible…

  31. dalpat chauhan Says:

    My project is voice recognizatio wheel chair.. Plz help me

  32. Ajay Verma Says:

    What kind of help u want??? ask..

  33. sukanya Says:

    i want code for voice controlle wheel chair using hm2007 its urgent please

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