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How to make a Voice Recorder?

Discussion in 'Embedded' started by Tolga Onbay, Nov 16, 2005.

  1. Tolga Onbay

    Tolga Onbay Guest

    I want to make a voice recorder using an MCU(8051 or PIC). The
    recording time doesn't matter at this time. I just want to learn how to
    digitalize inputted voice by a microphone and write it to internal RAM.
    And after this I want to learn how to make it voice again from 1s and
    0s format and send it to speaker.
     
    Tolga Onbay, Nov 16, 2005
    #1
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  2. Tolga Onbay

    Donald Guest

    Tolga Onbay wrote:
    > I want to make a voice recorder using an MCU(8051 or PIC). The
    > recording time doesn't matter at this time. I just want to learn how to
    > digitalize inputted voice by a microphone and write it to internal RAM.
    > And after this I want to learn how to make it voice again from 1s and
    > 0s format and send it to speaker.
    >


    App note and source files:

    Solid State Voice Recorder Using Flash MSP430

    http://focus.ti.com/docs/mcu/catalo...tract.jhtml?familyId=342&abstractName=slaa123
     
    Donald, Nov 16, 2005
    #2
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  3. Tolga Onbay

    Andrew Guest

    Tolga Onbay wrote:
    > I want to make a voice recorder using an MCU(8051 or PIC). The
    > recording time doesn't matter at this time. I just want to learn how
    > to digitalize inputted voice by a microphone and write it to internal
    > RAM. And after this I want to learn how to make it voice again from
    > 1s and 0s format and send it to speaker.


    You are never going to be able to use *Internal* RAM. Neither the PIC nor
    8051 have more than a few 100 bytes. Generating sounds from a pre recorded
    sample stored in ROM is possible but still limited by the size of available
    memory

    http://www.romanblack.com/picsound.htm gives a good guide to encoding sounds
    on a PC and playing back on a PIC.
    http://www.circuitcellar.com/magazine/180toc.htm follows on from the above
    (costs $1.50 to purchase)

    I would suggest looking at generating sound first, from samples recorded on
    a PC. Apart from anything else, if you start with the recording side you
    will end up with data that you have no idea as to whether it is correct or
    not.

    An alternative approach is to look at recognising speech rather than
    recording it.
    http://www.circuitcellar.com/pastissues/articles/Stewart91/text.htm
     
    Andrew, Nov 17, 2005
    #3
  4. Tolga Onbay

    Alex Gibson Guest

    "Tolga Onbay" <> wrote in message
    news:...
    >I want to make a voice recorder using an MCU(8051 or PIC). The
    > recording time doesn't matter at this time. I just want to learn how to
    > digitalize inputted voice by a microphone and write it to internal RAM.
    > And after this I want to learn how to make it voice again from 1s and
    > 0s format and send it to speaker.


    Winbond make single chip voice recorder.

    Need to look at pwm.

    Basically record the voice on a pc , just a few seconds at
    a low mono sample rate.
    Then convert it to

    Keil gives an example for their mcb2130 board.
    Examples comes with the eval version of their arm compiler.
    Just plays short samples of voice back using pwm.
    http://www.keil.com/demo/

    You can play music on the pic using a similar method.
    See www.beyondlogic.org ringtone example on a 16f877.

    For recording voice, look at using the adc on the chip you have.
    To start with try hooking up a little electric mic to one of the adc inputs
    and sampling it. Could send it to a pc via the usart and record and plot it
    to
    see what resolution it gives.

    Alex
     
    Alex Gibson, Nov 20, 2005
    #4
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