DRV8434S Vref at 15mV

I am just getting started with a DRV8434S breakout with potentiometer. It is powered with 3.3 V from an Adafruit Feather RP2040. The minimal configuration appears to be 3.3v, GND, SDI, SCLK, nSCS. I have also tried without the SPI pins connected. There is no motor or motor power yet. Vref reads from 0 to 19 mV. DVDD is about 38 mV. For some reason the chip appears to be shut down. I want to set Vref to 680 mV to limit the current at 514 mA and then control it by software. The schematic for the breakout shows a 10K pullup on nSLEEP and a pullup on nFAULT. So, I should be able to let these float while I adjust Vref. What am I missing?

Hello.

You will need to connect power to VM to power the driver and set the current limit. VSDO is a logic reference voltage.

Brandon

I see now that VSDO does not power DVDD. DVDD (which provides voltage to the reference voltage divider) is powered from the VM input to the DRV3834S chip. Thus, I need the motor power supply turned on to set VREF, even if no motor is connected. I will give that a try tomorrow. Thank you.

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