On 13/06/2018 14:16, R.Wieser wrote:
>> measuring between a GIPO & 5v reads
>> 0v, so they are both the same voltage.

No!

> And as the OP (correctly) stated, they are (thus) both at 5v.

No!

> And if his measurement is correct (and it is), and he reads 0v difference,
> than, as Mark has got the same result on his voltage meter, his leads should
> logically be at 5v too (even though they are not touching anything but air).

No!

If you measure between 2 pins and get 0V it /could/ mean they are at the
same potential, or it could mean there is *NO* connection between them.
That's why you always measure from the common ground to the pin.

Ground to 5V should give 5V
Ground to GPIO set high should give 3.3V
5V to GPIO should give 0V because they aren't connected.

---druck

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