C8051T620/1/6/7 & C8051T320/1/2/3
224
Rev. 1.2
Equation 26.1. UART1 Baud Rate
A quick reference for typical baud rates and system clock frequencies is given in Table 26.1.
Table 26.1. Baud Rate Generator Settings for Standard Baud Rates
Target Baud
Rate (bps)
Actual Baud
Rate (bps)
Baud Rate
Error
Oscillator
Divide
Factor
SB1PS[1:0]
(Prescaler Bits)
Reload Value in
SBRLH1:SBRLL1
SYSCLK =
12 MHz
230400
230769
0.16%
52
11
0xFFE6
115200
115385
0.16%
104
11
0xFFCC
57600
57692
0.16%
208
11
0xFF98
28800
28846
0.16%
416
11
0xFF30
14400
14388
0.08%
834
11
0xFE5F
9600
9600
0.0%
1250
11
0xFD8F
2400
2400
0.0%
5000
11
0xF63C
1200
1200
0.0%
10000
11
0xEC78
SYSCLK
= 24 MHz
230400
230769
0.16%
104
11
0xFFCC
115200
115385
0.16%
208
11
0xFF98
57600
57692
0.16%
416
11
0xFF30
28800
28777
0.08%
834
11
0xFE5F
14400
14406
0.04%
1666
11
0xFCBF
9600
9600
0.0%
2500
11
0xFB1E
2400
2400
0.0%
10000
11
0xEC78
1200
1200
0.0%
20000
11
0xD8F0
SY
SCLK = 48 MHz
230400
230769
0.16%
208
11
0xFF98
115200
115385
0.16%
416
11
0xFF30
57600
57554
0.08%
834
11
0xFE5F
28800
28812
0.04%
1666
11
0xFCBF
14400
14397
0.02%
3334
11
0xF97D
9600
9600
0.0%
5000
11
0xF63C
2400
2400
0.0%
20000
11
0xD8F0
1200
1200
0.0%
40000
11
0xB1E0
Baud Rate
SYSCLK
65536
(SBRLH1:SBRLL1)
–
---------------------------------------------------------------------------
1
2
---
1
Prescaler
----------------------
=