[sdiy] Communications with voices in a polyphonic synth

[Neil Johnson]

Hi,

Tom Wiltshire wrote: 
> The voices are based on the dsPIC 33FJ128GP802. This is my favourite  
> part currently because it's a 28-pin DIP and has a stereo audio DAC  
> on the chip.

Ok, so on that chip you have a choice of SPI, I2C, UART and CAN:

* I2C is limited to 400kHz if going off-board, but has HW support for in-band addressing.

* SPI as discussed looks like a no-no (too many pins).

* CAN goes up to 1Mbit, lots of HW support for addressing so minimising SW overhead.

* UART goes up to 10Mbaud, in 9-bit mode can do in-band addressing to minimise SW overheads.

I'd choose either CAN or UART and with differential signalling.  But - as has been asked already - what speed do you *NEED*..?

Neil
--
http://www.njohnson.co.uk