COP87L88KG Datasheet, PDF (22/42 Pages) National Semiconductor (TI) – 8-Bit One-Time Programmable (OTP) Microcontroller with UART and Three Multi-Function Timers

Baud Clock Generation (Continued)
TABLE III Baud Rate Divisors
(1 8432 MHz Prescaler Output)
Baud
Rate
Baud Rate
Divisor b 1 (N-1)
110 (110 03)
134 5 (134 58)
150
300
600
1200
1800
2400
3600
4800
7200
9600
19200
38400
1046
855
767
383
191
95
63
47
31
23
15
11
5
2
Note The entries in Table IV assume a prescaler
output of 1 8432 MHz In the asynchronous mode
the baud rate could be as high as 625k
TABLE IV Prescaler Factors
Prescaler
Select
Prescaler
Factor
00000
00001
00010
00011
00100
00101
00110
00111
01000
01001
01010
01011
01100
01101
01110
01111
10000
10001
10010
10011
10100
10101
10110
10111
11000
11001
11010
11011
11100
11101
11110
11111
NO CLOCK
1
15
2
25
3
35
4
45
5
55
6
65
7
75
8
85
9
95
10
10 5
11
11 5
12
12 5
13
13 5
14
14 5
15
15 5
16
As an example considering Asynchronous Mode and a CKI
clock of 4 608 MHz the prescaler factor selected is
4 608 1 8432 e 2 5
The 2 5 entry is available in Table IV The 1 8432 MHz pre-
scaler output is then used with proper Baud Rate Divisor
(Table V) to obtain different baud rates For a baud rate of
19200 e g the entry in Table IV is 5
N b 1 e 5 (N b 1 is the value from Table III)
N e 6 (N is the Baud Rate Divisor)
Baud Rate e 1 8432 MHz (16 c 6) e 19200
The divide by 16 is performed because in the asynchronous
mode the input frequency to the UART is 16 times the baud
rate The equation to calculate baud rates is given below
The actual Baud Rate may be found from
BR e Fc (16 c N c P)
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