Are pullups needed on TXx on Mega Serial lines?

I've just started using a Sparkfun "Mega Pro" to manage 3 USB ports which are Sparkfun FT232R FTDI cards. I've simply tied Rx of the FTDI to Tx on the Mega, and Tx of the FTDI to Rx on the Mega.

With a scope I see a nice near-5v transisions on Rx side of the Mega, but on the TX side the signal sits a bit high - neraly a float level - and doesn't make much of a voltage swing as the Mega sends data out.

This looks like the Tx pin on the Mega is begging for a pullup. I have seached around the net and haven't found any clear help.

I'm using the built-in Serial (is that Hardware Serial?) and simply do a "Serial1.begin(9600);" then do .reads, .writes and .prints to Serial1. The transmitted data does show on the recive side of the termial program (Termite 3.1), but occassionaly I see data coming from the Mega when it is idling and there is no data to echo - seems like noise on the Tx line - but the scope doesn't show any.

I thought it would be built in - doesn't Hardware Serial (Serial) take care of that?

=Alan R.

Outputs don’t need pullup resistors, only inputs. Outputs are either driven high or low as needed, no floating.

Ha! Found it it would have needed a VERY LARGE pullup -

The TX pin was shorted to ground on a mounting standoff on the FTDI board... BIG RED FACE!! :-*