CD1284 Datasheet, PDF (103/176 Pages) Intel Corporation – IEEE 1284-Compatible Parallel Interface Controller with Two High-Speed Asynchronous Serial Ports

IEEE 1284-Compatible Parallel Interface Controller — CD1284
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6.7
Baud Rate Tables
Table 22 through Table 26 indicate the values to be loaded into the RCOR/RBPR and TCOR/TBPR
to set the designated baud rate when using five standard frequency crystals. Table 22 uses a 25-
MHz frequency; Table 23 uses a 20.2752-MHz frequency, which yields near-perfect bit rates. Table
24 uses a 20-MHz frequency and shows error rates that are larger although still well within the
limits set by the various standards covering asynchronous communications. Table 25 also uses
another standard communications base frequency (18.432 MHz) that yields divisors with nearly
zero errors overall. However, since this frequency is below 20 MHz, performance at the higher
baud rates (76.8K and above) may be slightly lower and rates above 76.8K are not recommended.
Table 26 shows divisors for the lowest recommended operating frequency, 16 MHz.
Note: It is not necessary that both the receiver and transmitter of a channel be programmed to the same
baud rate; the CD1284 can send and receive at different rates on the same channel.
Table 22. Baud Rate Constants — CLK = 25 MHz
Baud Rate
R/TCOR¹
R/TBPR (Hex)
Error
110
4
6F
0.02%
150
4
51
0.47%
300
3
A3
0.15%
600
3
51
0.47%
1200
2
A3
0.15%
2400
2
51
0.47%
4800
1
A3
0.15%
9600
1
51
0.47%
19200
0
A3
0.15%
38400
0
51
0.47%
56000
0
38
0.35%
57600
0
36
0.47%
64000
0
31
0.35%
76800
0
29
0.76%
115200
0
1B
0.47%
128000
0
18
1.70%
150000
0
15
0.80%
NOTE:
1. In this and the following tables, R/T is used as a register abbreviation indicating Receive/
Transmit, followed by the register acronym.
Datasheet
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