Hi Alan,

The 8051 UART is designed to transmit 10 (mode 1) or 11 bits (mode 2 and 3): a start bit, 8 (or 9) bits of data, and a stop bit. Mode 0 transmits 8 data bits, but without the start and stop bits it's incompatible with normal serial use.

If you want to transmit 7 bits, you could pad your data with a '1' in the msb, and call it one start bit, 7 data bits, and two stop bits.

Dennis