DRV8711: Additional Observation: Only Channel-1 Working on 4-CH DRV8711 Board, Voltage Present at All Outputs, Request for Debug Assistance

Tool/software:

Dear Texas Instruments Technical Support Team,

I am following up regarding my ongoing issue with a custom 4-channel DRV8711 MOSFET-based stepper motor driver board (using SQJ952EP-T1_GE3 MOSFETs, single SPI, individual CS per channel, reference code from BOOST-DRV8711). I previously provided the source code for your review.

New Testing Results & Observations:

1. I have now thoroughly tested the board with the provided software:

   • Channel-1: Works and runs the stepper motor as expected.

   • Channels 2, 3, 4: Motors do not run—no observable movement or stepping.

2. Voltage Measurement Test (No Motor Connected):

   • With no motor connected, I measured the voltage at each DRV8711 output (AOUT1/AOUT2 and BOUT1/BOUT2) for all four channels.

   • All channels show 24V (the value supplied to VM) at these outputs.

   • When sending commands, the voltage at these output pins varies as expected according to software control, even though the motors themselves (when connected) do not run except on Channel-1.

Request for Support:

• Could you review these additional details and suggest possible causes or debugging steps?

• Based on the fact that all output pins on all channels are showing supply voltage and are responding in voltage to commands, is there likely an SPI/software issue, or is this evidence of a hardware/configuration issue with the rest of the driver channels?

• For context, the code uses separate CS for each DRV8711 and properly initializes each channel. Are there any common pitfalls in multi-DRV8711 setups (such as required delays, reset/nSleep handling, or register configuration) that could explain only one driver functioning?

Please let me know if you need logic analyzer waveforms, register dump snapshots, or additional code/hardware information.

Thank you in advance for your valuable assistance

Thanks & Regards,

Upendra