I just tried to build an Xylobox. I added a third MCP3008. Everything works ok until I add the MCP23s17. Then the Output of the MCP3008's begin to jitter (value-64-value etc). The 23s17 does its work (displays the right patchnumber and drives the two LEDs).
Things I have done:
I moved the SPI-chips close to the Axoloti
I tried various caps on the powerrails
Checked , double and tripplechecked every connection
Swapped al the chips
Changed the tranferspeed
Looks like the MCP3008's and the MCP23s17 don't match.
So I have a faulty batch of one of the chips or there is a mis-match in the use of the protocol.
Someone tells me what I overlooked...
Change the MCP23s17 to a MCP23017 (move the chip from the SPI-bus) Problem with that is that I can't find a driver/implementation of the MCP23017 chip for Axoliti anywhere...
Realy hope this community can shed some light on my problem.