at89c51re2-slsem ATMEL Corporation, at89c51re2-slsem Datasheet - Page 101

• Manufacturer Part Number: at89c51re2-slsem
• Description: At89c51re2 8-bit Flash Microcontroller
• Manufacturer: ATMEL Corporation

Internal Baud Rate Generator
(BRG)
Figure 26. Internal Baud Rate generator 0
Figure 27. Internal Baud Rate generator 1
84
AT89C51RE2
BRR_1
BRR_0
F
F
PER
PER
The AT89C51RE2 implements two internal baudrate generators. Each one is dedicated
to the coresponding UART. The configuration and operating mode for both BRG are
similar. When an internal Baud Rate Generator is used, the Baud Rates are determined
by the BRG overflow depending on the BRL (BRL or BRL_1 registers) reload value, the
value of SPD (or SPD_1) bit (Speed Mode) in BDRCON (BDRCON_1) register and the
value of the SMOD1 bit in PCON register.
•
Baud_Rate =
BRL = 256 -
The baud rate for UART is token by formula:
/6
/6
6
6
(1-SPD)
(1-SPD)
SPD_0
2
2
SPD_1
SMOD1
SMOD1
0
0
1
1
⋅ 32 ⋅ (256 -BRL)
⋅ 32 ⋅ Baud_Rate
auto reload counter
auto reload counter
⋅ F
⋅ F
PER
PER
BRL_0
BRL_1
BRG
BRG
overflow
overflow
/2
/2
SMOD1
SMOD1_1
0
0
1
1
INT_BRG
INT_BRG1
7663B–8051–03/07