High Power Stepper Motor driver 36v4 SPI with Vin

Hello All,

I have a High Power Stepper Motor driver 36v4 with SPI interface.
I notice some odd SPI signal level behavior for the SDATO when having the +12VDC to Vin pin. See my SPI level out.

Signal should be at 0VDC. When I disconnect the +12VDC, the digital signal logic then is 0VDC and +3VDC. Is this typical behavior? I would not expect supply voltage to the driver board to have an effect on the digital logic.

I am at the early stages of trying to get a successful read from the driver control register via SPI. I have signals going out but can’t get nothing out. If anyone has driven this driver with raspberry pi (SPI), please share.

. Using Raspberry Pi4
. Python3
. SPI interface via spidev

Current state: SPI out of Pi MOSI with SCLK, and active high CS0, but no SDOUT.
<without +12VDC at driver Vin>

Any help appreciated

Thank you

Since we already have an ongoing email discussion with additional context about this same subject, let’s continue troubleshooting there.