1. This forum section is a read-only archive which contains old newsgroup posts. If you wish to post a query, please do so in one of our main forum sections (here). This way you will get a faster, better response from the members on Motherboard Point.

Adding voice feedback to an electronics product? (voice chip)

Discussion in 'Embedded' started by techman41973, Oct 8, 2005.

  1. techman41973

    techman41973 Guest

    I have an electronics product application where I need voice feedback
    to feature selections.
    I am considering using a ISD2560 from Windbond's chipcorder series
    They seem quite popular (based on web search). However, unless I use
    their consulting services for them to pre-burn a large number of chips,
    I have to manually speak each voice clip into a small electret
    microphone for each unit. This is time consuming with questionable
    quality from such a recording interface.
    Are there any other voice chip alternatives? Ideally a voice chip that
    interfaces to an external ROM or Flash chip. Of course some type of
    software would need be provided that would allow me to compile voice
    clips on my PC to compatable ROM files.
    I am also incorporating an PIC18Fxxxx microprocessor into this product.
    Perhaps someone has been able to use a PIC processor to emulate a voice
    chip. I would appreciate any advice.
    techman41973, Oct 8, 2005
    1. Advertisements

  2. techman41973

    Tim Wescott Guest

    You should be able to make a setup to record sound into the winbond
    chips automatically, without using their setup.

    But depending on how much flash you have, how much work you want to do,
    and what voice quality you want you should also be able to store your
    sounds digitally in flash and play them back. You may need to use an
    external ADC.

    You could use wav files, which I think are 16 bit with selectable
    sampling rates. You should be able to sample at 8kHz for just voice,
    which would imply about 16kB/sec of sound. That's about 64 seconds/MB,
    which isn't too bad but isn't much to write home about. You'd need at
    least a 12-bit DAC, and carefully conditioned sound (but you'll want
    that anyway). This would be simple to implement in the PIC software;
    you'd just be shuttling bits around.

    You could use mu-law or a-law encoding, which will give you telephone
    quality and cut your memory requirements in half. You can still get
    mu-law codecs (at least I think you can), so you'd only have to shuttle
    8 bits/sample.

    You could use ADPCM (do a web search) at just about any level of
    compression you were willing to tolerate, with up to 8 times smaller
    files than mu-law (IIRC, it's been a while). This would load the PIC
    much heavier, but I _think_ it'd be up to the task as long as you're not
    asking it to do much else.

    Modern cell phone style compression where you have a model of the vocal
    tract is out unless you use something other than a PIC, and I suspect
    it's beyond what you want to tackle anyway.
    Tim Wescott, Oct 8, 2005
    1. Advertisements

  3. I read in sci.electronics.design that wrote (in
    <>) about 'Adding
    voice feedback to an electronics product? (voice chip)', on Fri, 7 Oct
    You can record a whole bunch at once using any microphone you want and
    an audio mixer or even an amplifier with a microphone input. Connect the
    chips in parallel to the output of the mixer or amplifier thorough a
    simple two-resistor attenuating pad. You need only a few millivolts for
    recording by your mixer or amplifier will produce much more.

    You can get quite good electret mics at low prices.
    John Woodgate, Oct 8, 2005
  4. techman41973

    PeteS Guest

    Regarding Tim's comments

    Motorola SPS (now Freescale) was the usual source for ADPCM codecs, but
    they seem to be getting out of the business, which is quite a blow as
    everyone seemed to use their parts.
    I recently went through this as I am just bringing some new products
    into production that include voice (and voice prompt feedback).

    Voice codecs using mu-law / A-law / 2s complement are available from a
    number of sources, including TI. Typical cost is about $2 - $3 in 1k

    There are software packages around that permit you to use a PC to
    record sound to virtually any format you wish, including mu/A law and
    2s complement formats.

    Driving a codec is fairly simple using a PIC that's fast enough. The
    key is to meet the bit timing requirements (typically 64kb/s minimum
    for mu/A law encoded data) which should not be beyond a PIC.

    As noted, these formats are all 8k frame rate. The codecs can be set to
    generate the frame pulse so you can sync a processor up easily.

    To deal with .wav files you would need to use a device capable of AC97
    (such as the Philips 14000 series or the Wolfson WM9712 for example)
    which requires a separate AC97 controller - that would probably be
    beyond what you need, and probably beyond your budget.

    For what it's worth, I ended up using the TI TWL1103T-Q1 (because I
    also have to run those prompts across a bluetooth link) for the codec.

    Just my $0.02


    PeteS, Oct 8, 2005
  5. techman41973

    Alex Gibson Guest

    Also their text to speech chips send the message as asci text

    Use in

    Alex Gibson, Oct 8, 2005
  6. techman41973

    mhahn Guest

    You could always try: http://www.romanblack.com/picsound.htm

    I've messed around with it enough to produce sounds, but never tried to
    do voice.

    You'd need an external eeprom, since I doubt you'd get to hold much
    speech in the 18fxxxx, but if you have 4 or 5 pins open it should work.

    mhahn, Oct 8, 2005
  7. techman41973

    Pooh Bear Guest

    Uh ?

    Mask ROM and 2.4 secs playback ? Not much good for anything I'd have thought.

    Pooh Bear, Oct 8, 2005
  8. Markus Knauss, Oct 8, 2005
  9. techman41973

    Jim Stewart Guest

    The very first product my company ever did was a natural
    voice speach playback board for LLNL. It was a Multibus
    form factor board with an Oki decoder, a homebrew 3-4 watt
    audio amp, 24 sockets for 27C256 eproms, and a couple
    dozen TTL chips. They used the boards in their security
    system to prompt users as they passed through access points.

    I think it would hold 2 or 3 minutes of speech, addressable
    at 1/2 second intervals.

    We also had to design a capture board for a PC and write
    the capture software. My next-door neighbor did the

    I've been looking at doing an updated version using MP3
    files and possibly an ARM chip doing software decoding.
    The current batch of MP3 decoder chips are all too
    expensive for hardware decoding. I'd want to have the
    files storeable on a compactflash with a FAT filesystem
    so they'd be trivial to transfer from a PC to the play-
    back board.
    Jim Stewart, Oct 10, 2005
  10. In our design we use the EM55M450 Module with OTP. It's o.k. for our 12
    sec gong.

    Markus Knauss, Oct 10, 2005
  11. ISD had once the ISD-t360

    Nice chip i used in a project with DTMF en/de coding and other PSTN stuff
    (tone detection for call progress ...)

    External flash up to 64Mb for up to 60 min of sound (8000samples / s )

    Winbond took over the ISD business and stopped the production of this nice
    product , shame on Winbond ! )

    I never found a replacement chip that had all of this in a single chip
    Sagaert Johan, Oct 10, 2005
    1. Advertisements

Ask a Question

Want to reply to this thread or ask your own question?

You'll need to choose a username for the site, which only take a couple of moments (here). After that, you can post your question and our members will help you out.