at89c51rc2-slsil ATMEL Corporation, at89c51rc2-slsil Datasheet - Page 48

• Manufacturer Part Number: at89c51rc2-slsil
• Description: 8-bit Microcontroller With 16k/ 32k Bytes Flash
• Manufacturer: ATMEL Corporation

Internal Baud Rate Generator
(BRG)
Figure 21. Internal Baud Rate
48
AT89C51RB2/RC2
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 =
F
BRL = 256 -
Clk Periph
(T2CON)
The baud rate for UART is token by formula:
TCLK
0
1
0
1
X
X
0
1
X
6
6
(1-SPD)
(1-SPD)
÷ 6
2
2
(T2CON)
SMOD1
SMOD1
⋅ 32 ⋅ Baud_Rate
⋅ 32 ⋅ (256 -BRL)
RCLK
BDRCON.1
X
X
X
0
0
1
1
0
1
SPD
⋅ F
⋅ F
0
1
PER
PER
BDRCON.4
(BDRCON)
BRR
TBCK
0
0
0
0
1
1
0
0
1
(8 bits)
(8 bits)
BRG
BRL
(BDRCON)
RBCK
0
0
0
0
0
0
1
1
1
Overflow
Clock Source
UART Tx
INT_BRG
INT_BRG
INT_BRG
÷ 2
Timer 1
Timer 2
Timer 1
Timer 2
Timer 1
Timer 2
SMOD1
PCON.7
0
1
4180E–8051–10/06
Clock Source
UART Rx
INT_BRG
INT_BRG
INT_BRG
Timer 1
Timer 1
Timer 2
Timer 2
Timer 1
Timer 2
INT_BRG