Vpu pin powering the board?

January 09, 2010, 07:02:19 pm

I was surprised to see voltage set onto the Vpu pin powering the board when I disconnected the bus pirate from my USB port. Is this meant to happen. I've only just started playing with the BP tonight and thought it was strange. I'm putting 5V on the Vpu pin.

Re: Vpu pin powering the board?

Reply #1 – January 10, 2010, 08:53:57 am

It is certainly possible that the PIC could be back-powered by the voltage on the I/O pins and Vpu ADC. Operation is undefined when it's not powered. If it's connected to an external power source, I try to disconnect the probes before unplugging the USB cable.