Hi, Steven,

You said:
In mode 0, The data is sent or received on RXD pin and the clock is provided on TXD. But why in the uart_mode_0.gif you provided, I saw two pins for data, one is for data in, the other is for data out.

Another question is:
Do you mean in the "asynchronous modes", data is not received at the baud rate but is only transmitted out at the baud rate?

Rgds, Billy