Vref not reading on TB67S128FTG

Is there any reason why I cannot get a vref reading from my TB67S128FTG? I dont get a reading from the POT nor the VREF pin. I only have IOREF powered with 3.3v based on the Pololu video for setting vref. This is my first attempt at a sophisticated stepper driver. I am very familiar with the A4988 and TMC2130.

From your more recent post, it sounds like you were able to successfully set the current limit. Is that the case? If so, could you share what the problem was for anyone else who comes across this post with a similar issue?


Hi Brandon! I assumed the TB67S128FTG was designed not to provide Vref reading unless VM/GND were powered… at this point Im not sure if that is correct or not. It might have caused the LO1 error but I am not sure. Im still waiting on some help…

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Yes, it requires power to VIN and GND for VREF to be read, so if you were not supplying power, that would explain it.


Great! Thanks for confirming!