I have just hooked up a new TMC 429, and I am trying to test the comm connection by reading out the firmware version register (0x73 as first 8 bits of datagram). I think I should be getting 0x42 0x91 0x01, but instead I see 0x00 0x32 0x31. I verified this on my o'scope, so it's not just bad interpretation by the SPI routine on my host. Any hints?
EDIT: As it turns out, things work as I expected when doing the SPI comm from an AVR directly. I experienced the strange responses while trying to use a "Bus Pirate" board to quickly get the system up and running. I tried several variants of the SPI settings with the Bus Pirate, but never got a sensible conversation going between the two. Just an FYI for anyone else trying that.