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[on:]

I have successfully got the PCM audio example working:
http://playground.arduino.cc/Code/PCMAudio

However I want to use the SPI library to control a MCP23S17 (16bit I/O expander). 
http://arduino.cc/en/Reference/SPI

The SPI library has to use pins 10,11,12 & 13 to connect to the MCP23S17.  However, the PCM audio example also outputs on pin 11.  Does anyone have a link to a reference table for all the constants used in the PCM example to setup the registers (e.g. COM2A1, COM2A0 etc).

Am I correct in thinking that if I change these constants, I should be able to use one of the PCM pins lower down the board (pin 3,5 or 6) instead of 11?

thanks
Paul

[Reply #1 on:]

If you configure it correctly you should be able to user Timer 2 "B" output (pin D3).

Some stuff about timers:

http://www.gammon.com.au/forum/?id=11504


Or you could use the USART in SPI mode to get the SPI going (if you don't mind not using the Serial output).

http://www.gammon.com.au/forum/?id=10892&reply=3#reply3

[Reply #2 on:]

Wow, your page on interrupts is amazing!  I can't use the serial, but I can use pin D3, so guess the quick fix is to swap the COM2As for COM2Bs and vice versa in the Timer 2 setup.  I'll try and use your helper library soon though.  Will make the whole thing a lot easier!