AT89C51RB2-RLTCM ATMEL [ATMEL Corporation], AT89C51RB2-RLTCM Datasheet - Page 46

• Manufacturer Part Number: AT89C51RB2-RLTCM
• Description: 8-bit Microcontroller with 16K/ 32K Bytes Flash
• Manufacturer: ATMEL [ATMEL Corporation]

Internal Baud Rate Generator
(BRG)
Figure 20. Internal Baud Rate
46
AT89C51RB2/RC2
CLK PERIPH
BRR
Table 32. Baud Rate Selection Table UART
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.
•
Baud_Rate
(BRL) = 256 -
(T2CON)
The baud rate for UART is token by formula:
TCLK
X
X
X
0
1
0
1
0
1
/6
=
SPD
(T2CON)
0
2 x 2 x 6(1-SPD) x 16 x [256 - (BRL)]
1
RCLK
2 x 2 x 6
Auto Reload Counter
X
X
X
0
0
1
1
0
1
2
SMOD
2
SMOD
(1-SPD)
1 x F
BRG
BRL
(BDRCON)
1 x F
TBCK
x 16 x Baud_Rate
CLK PERIPH
0
0
0
0
1
1
0
0
1
CLK PERIPH
Overflow
(BDRCON)
RBCK
/2
0
0
0
0
0
0
1
1
1
SMOD1
0
1
Clock Source
UART Tx
INT_BRG
INT_BRG
INT_BRG
Timer 1
Timer 2
Timer 1
Timer 2
Timer 1
Timer 2
INT_BRG
4180B–8051–04/03
Clock Source
UART Rx
INT_BRG
INT_BRG
INT_BRG
Timer 1
Timer 1
Timer 2
Timer 2
Timer 1
Timer 2