Alister,

> Tx & RX are described as TTL serial TTL is a
> fully detailed standard as far as signal levels go.

Your second mistake.

Just take a look here:

https://www.sparkfun.com/tutorials/215

"Serial communication at a TTL level will always remain between the limits
of 0V and Vcc, which is often 5V or 3.3V"

Nowerdays a "TTL signal" often doesn't refer to the voltage, but to the
"low"/"zero" level being at 0v, and the "high"/"one" level being at VCC
(regardles of what VCC might be) - as opposed to an RS232 specced signal,
where "low" is at +v and "zero" at -v.


And I see that you did not read my initial message too closely.   In it I
wrote that the RXD and TXD pins are specced as having 3.3v levels ...

Regards,
Rudy Wieser

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