hi,

By the way, this 7-bit transfer (1 start bit + 7 data bits + 1 stop bit) may cause a problem when used with UART of 8051. The reason is that if source device uses continuous stream for sending two or more bytes (for example, when FIFO is used) then 8051 as destination device will not be able to receive data correctly. Here is the example:
- source sends start bit; 8051 detects it;
- source sends 7 data bits; 8051 receives them;
- source sends stop bit; 8051 receives it as 8th data bit;
- source sends start bit of the new transfer; 8051 comes to the trouble! The derivatives which have Frame Error detector activated, report about "invalid stop bit" and lost syncronization with the next byte. Other derivatives just miss the second start bit. In any case, only the first byte has been received [right], other bytes will be wrong.

So be careful when connect to 8051 device with 7+1 bits protocol. However, 8051 works good with 7+2 protocol (where two stop bits are used).

Regards,
Oleg