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Voltage on a GPIO in HighZ Mode | Cypress Semiconductor

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Voltage on a GPIO in HighZ Mode

Last Updated: January 01, 2012

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.

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