Datasheet

51
AT89C51IC2
4301D–8051–02/08
Internal Baud Rate Generator
(BRG)
When the internal Baud Rate Generator is used, the Baud Rates are determined by the
BRG overflow depending on the BRL reload value, the value of SPD bit (Speed Mode)
in BDRCON register and the value of the SMOD1 bit in PCON register.
Figure 21. Internal Baud Rate
• The baud rate for UART is token by formula:
Peripheral clock
BRG
0
1
/6
BRL
/2
0
1
INT_BRG
BRR
auto reload counter
overflow
SPD
BaudRate
2
SMO D
F
CLKP ERIP H
×
2 2 6×× 1 SPD–〈 〉 16× 256 BRL( )–[ ]×
----------------------------------------------------------------------------------------------------------
=
BRL( ) 256
2
SMOD 1
F
CLKP ERIP H
×
2 2 6××
1 SPD–( )
16× BaudRate×
-----------------------------------------------------------------------------------------
–=