Erik,

There will be always some error everywhere, an baud rate is not an exception. Therefore, the question is how much error is permitted in the application, and design for the worst case.

Crystals are not perfect. The serial signal includes switching delays due to the transmitter and also suffers from distorsion due to the transmission line.

The experience says that a little error in the baud rate is acceptable.

The use of timer 2 extends the number of baud rates we can select for the 8052 serial port.

Alfredo del Rio.