Hi David,

You need to go through the 8051 bible, see links.

If the timer's timer or counter selector is set to 1 (which it *isn't* for T0 in your setting of TMOD) then it can count based on the T0 input pin.

However, T0 can't drive the baud rate, but you can use T1 if you wish to do that. I see that you've already got T1 set up as a counter...but did you intend to use it in 8 bit autoreload mode?

Dennis