The DRV8711 isn’t responding to SPI reads and I am wondering if this is because I haven’t connected the motor drive voltage. I don’t want to connect the motor supply voltage until I have a set a low current limit via SPI. Of course there could be another reason why SPI isn’t responding, although I think I have tried all combinations of clock and data modes without success.
You will need to supply power to the 36v4 High-Power Stepper Motor Driver’s VIN and GND pins for the logic interface on the DRV8711 to work. Can you try that?
If you continue having trouble, please post pictures of your setup that show all of your connections and solder joints.
By the way, you should not have to worry about the current limit not being set since you still need to enable the driver through the SPI interface before it will activate any of the outputs; just make sure you include a command to set the current limit before sending the enable command.