Hi
thats cool. I'll be following this to see what you've managed to do .
the TMC222's are similar and they're available through element14
http://au.element14.com/trinamic/tmc...c20/dp/1214195
did you get the eval board or just the chip?
which mcu are you planning to use to interface?
I2C is easy as its just the master/slave config and addressing that needs to be right. more crucial is sending the right commands and getting the ack back.
also, i think one of these don't do constant velocity, you've got to send a max position, reset and send the max position again and repeat if you want continuous motion.
oh and don't forget the pullup resistors on the I2C bus.