at89c51rd2-smsum ATMEL Corporation, at89c51rd2-smsum Datasheet - Page 52

• Manufacturer Part Number: at89c51rd2-smsum
• Description: 8-bit Flash Microcontroller
• Manufacturer: ATMEL Corporation

14.4.1
Figure 14-5. Internal Baud Rate
52
AT89C51RD2/ED2
Internal Baud Rate Generator (BRG)
Table 14-3.
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 =
• The baud rate for UART is token by formula:
BRL = 256 -
(T2CON)
TCLK
X
X
X
0
1
0
1
0
1
F
Clk Periph
6
6
(1-SPD)
(1-SPD)
Baud Rate Selection Table UART
2
2
SMOD1
SMOD1
⋅ 32 ⋅ Baud_Rate
⋅ 32 ⋅ (256 -BRL)
(T2CON)
RCLK
÷ 6
X
X
X
0
0
1
1
0
1
⋅ F
⋅ F
PER
PER
BDRCON.1
SPD
0
1
(BDRCON)
TBCK
0
0
0
0
1
1
0
0
1
BDRCON.4
BRR
(BDRCON)
(8 bits)
(8 bits)
RBCK
BRG
BRL
0
0
0
0
0
0
1
1
1
Overflow
Clock Source
INT_BRG
INT_BRG
INT_BRG
UART Tx
Timer 1
Timer 2
Timer 1
Timer 2
Timer 1
Timer 2
÷ 2
SMOD1
PCON.7
0
1
Clock Source
4235J–8051–01/08
UART Rx
INT_BRG
INT_BRG
INT_BRG
Timer 1
Timer 1
Timer 2
Timer 2
Timer 1
Timer 2
INT_BRG