C8051T620/1/6/7 & C8051T320/1/2/3
222
Rev. 1.2
Table 25.1. Timer Settings for Standard Baud Rates
Using The Internal 24.5 MHz Oscillator
Frequency: 24.5 MHz
Target
Baud Rate
(bps)
Baud Rate
% Error
Oscillator
Divide
Factor
Timer Clock
Source
SCA1–SCA0
(pre-scale
select)
1
T1M
1
Timer 1
Reload
Value (hex)
SYS
CLK from
Internal Osc.
230400
–0.32%
106
SYSCLK
XX
2
1
0xCB
115200
–0.32%
212
SYSCLK
XX
1
0x96
57600
0.15%
426
SYSCLK
XX
1
0x2B
28800
–0.32%
848
SYSCLK/4
01
0
0x96
14400
0.15%
1704
SYSCLK/12
00
0
0xB9
9600
–0.32%
2544
SYSCLK/12
00
0
0x96
2400
–0.32%
10176
SYSCLK/48
10
0
0x96
1200
0.15%
20448
SYSCLK/48
10
0
0x2B
Notes:
1.
SCA1
–
SCA0 and T1M bit definitions can be found in
2.
X = Don’t care.
Table 25.2. Timer Settings for Standard Baud Rates
Using an External 22.1184 MHz Oscillator
Frequency: 22.1184 MHz
Target
Baud Rate
(bps)
Baud Rate
% Error
Oscillator
Divide
Factor
Timer Clock
Source
SCA1–SCA0
(pre-scale
select)
1
T1M
1
Timer 1
Reload
Value (hex)
SY
SCLK from
External Osc.
230400
0.00%
96
SYSCLK
XX
2
1
0xD0
115200
0.00%
192
SYSCLK
XX
1
0xA0
57600
0.00%
384
SYSCLK
XX
1
0x40
28800
0.00%
768
SYSCLK / 12
00
0
0xE0
14400
0.00%
1536
SYSCLK / 12
00
0
0xC0
9600
0.00%
2304
SYSCLK / 12
00
0
0xA0
2400
0.00%
9216
SYSCLK / 48
10
0
0xA0
1200
0.00%
18432
SYSCLK / 48
10
0
0x40
SYSCLK from
Internal
O
s
c.
230400
0.00%
96
EXTCLK / 8
11
0
0xFA
115200
0.00%
192
EXTCLK / 8
11
0
0xF4
57600
0.00%
384
EXTCLK / 8
11
0
0xE8
28800
0.00%
768
EXTCLK / 8
11
0
0xD0
14400
0.00%
1536
EXTCLK / 8
11
0
0xA0
9600
0.00%
2304
EXTCLK / 8
11
0
0x70
Notes:
1.
SCA1
–
SCA0 and T1M bit definitions can be found in
.
2.
X = Don’t care.