MOTOROLA
9-32
ASYNCHRONOUS SERIAL COMMUNICATIONS INTERFACE
M68HC11
REFERENCE MANUAL
TE can be written to one anytime in the interval from [1] to [3]; it will be recognized at
the falling edge of Tx clock [4]. The rising edge of TE [1] is too late relative to the falling
edge of internal Tx clock [2]. The rising edge of TE [3] is in time to be recognized at
the falling edge of internal Tx clock [4]. This reflects an uncertainty about the delay
from writing TE to one and when the SCI transmitter actually takes control of the TxD
pin. The pin functions as the general-purpose I/O pin (PD1) until [5] where the SCI
Table 9-3 Baud Rates by Crystal Frequency, SCP[1:0] and SCR[2:0]
SCP
1
SCP
0
SCR
2
SCR
1
SCR
0
Crystal Frequency
4.9152 MHz
Baud Rates
38.40K Baud
19.20K Baud 15.625K Baud
15.625K Baud
9600 Baud
7812.5 Baud
4800 Baud
3906 Baud
2400 Baud
1953 Baud
1200 Baud
977 Baud
600 Baud
41.666K Baud 25.60K Baud 20.833K Baud
20.833K Baud 12.80K Baud 10.417K Baud
10.417K Baud
6400 Baud
5208 Baud
3200 Baud
2604 Baud
1600 Baud
1302 Baud
800 Baud
651 Baud
400 Baud
326 Baud
200 Baud
31.250K Baud 19.20K Baud 15.625K Baud
15.625K Baud
9600 Baud
7812.5 Baud
4800 Baud
3906 Baud
2400 Baud
1953 Baud
1200 Baud
977 Baud
600 Baud
488 Baud
300 Baud
244 Baud
150 Baud
9600 (+0.16%)
5908 Baud
4800 Baud
2954 Baud
2400 Baud
1477 Baud
1200 Baud
738 Baud
600 Baud
369 Baud
300 Baud
185 Baud
150 Baud
92 Baud
75 Baud
46 Baud
2 MHz
1.2288 MHz
Bus Frequency (E clock)
2
23
Hz
8 MHz
4 MHz
3.6864 MHz
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
0
0
0
1
1
1
1
0
0
0
0
1
1
1
1
0
0
0
0
1
1
1
1
0
0
0
0
1
1
1
1
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
65.536K Baud
32.768K Baud
16.384K Baud
8192 Baud
4096 Baud
2048 Baud
1024 Baud
43.691K Baud
21.845K Baud
10.923K Baud
5461 Baud
2731 Baud
1365 Baud
683 Baud
341 Baud
32.768K Baud
16.384K Baud
8192 Baud
4096 Baud
2048 Baud
1024 Baud
512 Baud
256 Baud
10.082K Baud
5041 Baud
2521 Baud
1260 Baud
630 Baud
315 Baud
158 Baud
79 Baud
2.1 MHz
62.50K Baud
31.25K Baud
31.25K Baud
28.80K Baud
14.40K Baud
7200 Baud
3600 Baud
1800 Baud
900 Baud
450 Baud
19.20K Baud
9600 Baud
4800 Baud
2400 Baud
1200 Baud
600 Baud
300 Baud
150 Baud
14.40K Baud
7200 Baud
3600 Baud
1800 Baud
900 Baud
450 Baud
225 Baud
112.5 Baud
4431 Baud
2215 Baud
1108 Baud
554 Baud
277 Baud
138 Baud
69 Baud
35 Baud
921.6 kHz
7812.5 Baud
3906 Baud
1953 Baud
977 Baud
488 Baud
5208 Baud
2604 Baud
1302 Baud
651 Baud
326 Baud
163 Baud
7812.5 Baud
3906 Baud
1953 Baud
977 Baud
488 Baud
244 Baud
122 Baud
4800 (+0.16%)
2400 Baud
1200 Baud
600 Baud
300 Baud
150 Baud
75 Baud
38 Baud
1 MHz