[sdiy] dsPIC interfacing with multiple CODEC chips

[Steve Lenham]

----- Original Message ----- 
From: "Seb Francis" <seb at burnit.co.uk>

> Well, I think I'm going to solve it by using 2 PICs.  It's not too big a 
> deal - the only tricky part will be making them talk to each other as they 
> will need to share the same LED display to show the delay time when a knob 
> is turned.

I think that's a perfectly good solution for your application (I couldn't do 
that as I needed four stereo channels and had to be able to mix/switch 
between them, which is hard without having them all on one device).

> The SPI/I2C interface of the CODEC is only for controlling device 
> configuration.  The actual audio data is transferred via an I2S interface 
> which unfortunately doesn't have a chip select line or any kind of 
> addressing.

When David mentioned SPI and I2C I think he was suggesting that they could 
be used for communication between your two PICs, not for audio transfer. I 
was about to suggest the same thing. All you need to do is make one PIC the 
master, reading all the pots, switches etc. and driving the display, then 
have it send commands to the other, slave PIC via one of these interfaces.

(Can't resist pointing out that in fact the PIC SPI ports are capable of 
10Mbit/s, which IS fast enough to transfer digital audio data between 
devices. You're right that it doesn't use the same format as the converters, 
though).

Good luck with the project!

Cheers,

Steve L.