I have a tentative request from a client to add sound effects to a vending machine application. It would be about half a dozen sound effects in the 1s ballpark, and perhaps two sound effects in the 10s ballpark. Doesn't have to be field-upgradable. I want something equivalent to roughly 11.025kHz 8-bit PCM (5-bit ADPCM would be fine).
My options seem to be:
- EPROM with raw sample data, reloadable counter with 11025Hz clock source, and DAC.
- ISD chips. Kinda expensive (especially to get factory-programmed) and the audio quality is variable.
- ISTR from my arcade machine days a range of ADPCM parts from Oki; they were typically controlled by an 8-bit micro and read sample data right out of a dedicated EPROM. Can't find these parts any more though.
I can't spend much CPU time on this because the whole machine is controlled by an ATmega32L running at 1MHz and I can't afford such a fast timer; it would interfere with my other processes. The solution needs to be primarily hardware.
Has anyone faced and solved this problem in a simple way? Volumes are very low; maybe a couple of thousand over two years. And it's not a fersure thing so I would rather have off-the-shelf parts (with an EPROM or flash chip I can burn myself) than some custom-programmed part.
Yes (this note to Guy Macon :) I have considered masked toy parts but I don't like the MOQ.