Question re: LC pin voltages

[Constantin]

Hi guys and gals of Teensy Land,

I have a home-rolled LC clone here (scavenged a LC bootloader, bought the MCU) and note some interesting voltages on unused pins here. Unlike the PJRC-sourced Teensy LC boards I have (happily blinking away on their default program when plugged into the USB port), the LC clone MKL26Z seems to feature voltages as high as 2.1VDC on 'un-assigned' pins.

Once a particular pin has been assigned a pinmode and the blink program for example, it behaves as expected.

Any idea what might be driving these phantom pin voltages?

 

[PaulStoffregen]

You might try touching those pins with a 100K resistor connected to either GND or 3.3V, to get an idea whether the voltage you're seeing is actually being driven by something, or a "random" result from a very high impedance (like tiny leakage currents through transistors and a very high impedance measurement that's sensitive to such things).