This is kind of embarrassing to admit, but I just haven’t been able to get anything but a measurement of 0V when attempting to find the VREF on an MP6500 that I picked up. I’m using an Arduino UNO to provide the 5V logic power and my benchtop power supply for the motor (the motor isn’t hooked up yet).
I’ve tried both minimum wiring diagrams and had similar lack of success using both. From using other A4988 carriers, I know that VREF can be found of them by only connecting the SLEEP and RESET and providing logic power. For the life of me, though, I just can’t figure out what the absolute minimum required to test the VREF on the MP6500 is though. I’ve been through all the documentation, but I’m also a bit sleep deprived, so I would appreciate some suggestions.