I'm having some trouble driving LEDs from my Raspberry Pi, so I started poking around with my multimeter, and the voltages seem very wrong.
Compared the the ground port, the 5V0 ports show 4.6 V, which seems normal-ish. The 3V3 ports, however, seem to ramp sawtooth-wave style from 0 V to 390 mV (if I put my multimeter in AC mode, it reads either around .1 or .06 V.
gpio readall command on a newly rebooted Pi shows that GPIO 0 is set to IN and reads 0. My multimeter says this pin is at .14 V. If I run
gpio mode 0 out then
gpio write 0 1, the
readall command says that the pin is set to OUT and 1, but my multimeter still reads .14 V. The opposite is the case for GPIO 2: it starts off at 1 (and shows 4.6 V on my multimeter) and I cannot turn it off.
Edit: the test points (labelled TP1 and TP2 on the board) show 4.8 V.