MS51
Dec. 17, 2019
Page
238
of 316
Rev 1.01
M
S51
SE
RIES
TE
CHNICA
L REF
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A
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Following shows all UART mode and baudrate fomula:
Mode
Frame
Bits
SM0 / SM1
(SCON[7:6])
SM2
(SCON[5])
SMOD
(PCON[7])
Baud Rate
0
8
00
0
-
FSYS divided by 12
1
FSYS divided by 2
1
10
01
-
0
Time1
TM1 CKCON[3] = 0
TH1
-
256
12
F
32
1
SYS
Time1
TM1 CKCON[3] = 1
TH1
-
256
F
32
1
SYS
Timer 3
3)
RL
3
RH
(256
-
65536
scale
Pre-
F
32
1
SYS
1
Time1
TM1 CKCON[3] = 0
TH1
-
256
12
F
16
1
SYS
Time1
TM1 CKCON[3] = 1
TH1
-
256
F
16
1
SYS
Timer 3
RL3)
RH3
(256
-
65536
scale
-
Pre
F
16
1
SYS
2
11
10
-
0
FSYS divided by 64
1
FSYS divided by 32
3
11
11
-
0
Time 1
[1]
TM1 CKCON[3] = 0
TH1
-
256
12
F
32
1
SYS
Time 1
[1]
TM1 CKCON[3] = 1
TH1
-
256
F
32
1
SYS
Timer 3
RL3)
RH3
(256
-
65536
scale
-
Pre
F
32
1
SYS
1
Time1
[1]
TM1 CKCON[3] = 0
TH1
-
256
12
F
16
1
SYS
Time1
[1]
TM1 CKCON[3] = 1
TH1
-
256
F
16
1
SYS
Timer 3
3)
RL
3
RH
(256
-
65536
scale
Pre-
SYS
F
16
1
Note:
Timer 1 should configured as a timer in auto-reload mode (Mode 2).
Table 6.8-1 Serial Port UART0 Mode / baudrate Description
