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

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

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.

I read in sci.electronics.design that snipped-for-privacy@yahoo.com 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.

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 qtys.

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

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

Cheers

PeteS

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

Use in

Alex

You could always try:

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.

Mark

Uh ?

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

Graham

Take a look at

With the development environment for these EM55xxx chips, you can convert wav files and program them into the chip.

Volume and playback frequency are also adjustable.

Cheers Markus

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 narration.

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.

In our design we use the EM55M450 Module with OTP. It's o.k. for our 12 sec gong.

Markus

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 solution.