USB indicator stuck (BenF 3.61)

Hi All,

I’m running BenF 3.61, and it indicates USB, even after I unplug the cable and cycle power. It charges fine and it connects fine to my PC. The only issue is that I can’t see my battery indicator.

Any ideas?

It gets stranger. With no cable plugged in, USB is displayed. If I plug in to charge, USB is displayed. If I turn the computer power off, but leave the cable plugged in, the battery charge is displayed. After unplugging the USB cable from the powered-down PC, USB reappears.

I tried reprogramming the device with the same firmware, but no difference.

This is more than likely a hardware issue and if the unit is under warranty you may want to return it for repair.

If you’re handy with electronics and want to have a go at fixing it yourself, I would check the voltage across R26 first. This should read about 3.1V when connected to USB and 0V otherwise. This is the reference used by the firmware (through STM32 port B10) to determine if the unit is operating on battery or not.

Thanks for the reply, BenF.

I haven’t popped the cover yet, but there’s 3.3V on pin 1 of the USB cable, so I think that the FDFMA2P853 switch is shot. Not sure it’s worth messing with; I notice DigiKey doesn’t have any in stock.