I have a project in mind that requires many independent small speakers (8 for my first prototype, then 40+ when I know what I am doing). I will generate the tone with a 555, but i require a way to be able to control volume for each speaker. I am considering MCP4131 over SPI controlled by a pc running processing. Is this doable? How many spi devices can be controlled via a single arduino? Also is their a better (cheaper) way to control multiple voltages with an arduino?
Thanks
Haydn
As long as you can operate the appropriate CS pin on the pots I imagine you can use as many as you like. You could use a port extender chip to get more pins on an Uno - or use a Mega.
I presume the pots are going to control an amplifier for each speaker
...R
A 74138 demultiplexer/decoder chip will give you 8 chip selects with 3 digital pins. A 74154 gives 16 select signals with 4 pins used.
Yes, I'd go with 74HC138 or 74HC154 & MCP3208 ADCs.
3 address lines select 1 of 8 ADCs. Use 5-6 outputs, select 7 or 8 to not select any device.
Or use a 4th control line to not select any output.