jim@jpes.com wrote:
> Isn't a LOW logic signal always some magnitude above zero volts?

No.

A low logic signal will have some upper limit it is allowed, but zero volts
is almost always within the valid range.  Many PIC inputs require a logic
low input to not exceed .2 Vdd and allow it to be something like -300mV (no=
t
sure exactly, check datasheet).

In practise small negative voltages can occur due to ground offset, not eve=
n
considering short term transients.


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