The two AVRs I'm using right now (ATmega1284P and ATtiny4313) are both powered by 4.96V. I'm measuring a voltage on their /RESET pins of 6.33 volts. Is that normal? Where is it coming from?
I can think of two reasons:
AC voltage between measuring person body and psu gnd may get rectified by input protection diodes (or non-linear input impedance). Touch the gnd with your finger while measuring to see if the 6V drops to 5V.
(very unlikely) There might be an internal Vpp generator, for flash programming. It can have a little leak to the high-impedance reset/vpp pin.
Pretty much and old post but still here are my findings:-
I did try to measure the voltage between RESET and GND which came out to be around 4.2V on AVR running on 5V rail.
Also someone said reset is an input, well I am not sure, at least not in atmega328p. or infact even in the AVR architecture. most people do get confused because of the reset switch commonly found or connected as a best practice which would send an interrupt to the reset handler, basically its nothing but grounding the reset pin.
Usually at run state the reset is high, and at programming or flashing state it is momentarily set to ground or a low state. This principle is leveraged for instance it is applied in designing a board where you can program while the circuit is already active with different peripherals connected to miso mosi pins and modules which are continuously running. (incase you are using spi programmer)