TNP,

> FWIW there is somewhere the original TTL spec where 0 is less than some
> voltage and 1 is more than some voltage with in between being 'here be
> dragons'
>
> "A TTL input signal is defined as "low" when between 0 V and 0.8 V with
> respect to the ground terminal, and "high" when between 2 V and VCC (5 V)"

As you said, the origional TTL spec - for the classic 74xx series.

And thats just how the those chips interpreted /incoming/ signals.
/Outgoing/ signals where ofcourse safely quite below and above it.    A
logic "high" for them is defined as /at minimum/ 2.4v (under heavy load),
with no upper limit.

The problem is the HC-05 module /doesn't/ run on 5v - ever.  Its also a CMOS
device.  Both of which Alister seems to have overlooked.

Regards,
Rudy Wieser

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