Voltage on a GPIO in HighZ Mode

Question: When I place port0 to be in a Hi-Z mode, some of the pins are read with a voltage of 3V and above. I find this strange as the output pins should be disconnected from the drive in this mode. Why is the voltage appearing on the pins?



When a pin is configured as a High Z, the pin is floating and yes, it is disconnected from the drive source. But there is a small leakage current present on the pin.  This leakage current when combined with the very high impedance of the Oscillocope or Digital Multimeter probe will show some voltage.  This is a perfectly normal behaviour.  Connect a low value resistor in the order of a few 10's of kilo ohms between the pin and GND and this voltage will disappear.