Hi F Y!

The term 'polling' is used to describe the process of having your program manually check the status of a register bit/byte value, i.e. like what you're attempting to do with the RI flag in your example program.

From my observation, your code cannot work, since you are not checking if your 8051 UART has sucessfully sent out a byte of data In fact it looks to me as if you are constantly writing to SBUF (thus effectively 'resetting' the data transmisson already in progress..) while waiting for the RI flag to say 'i've got a data byte'..

So, my guess would be you will need to re-write your code to include checking of both the RI and TI flags. You may find a few ideas for this in the code library on this site..

Regards Valentin