com81c17 Standard Microsystems Corp., com81c17 Datasheet - Page 7

• Manufacturer Part Number: com81c17
• Description: Twenty Pin Uart Tpuart Corporation
• Manufacturer: Standard Microsystems Corp.

THE ON CHIP BAUD RATE GENERATOR
The TPUART incorporates an on chip Baud
Rate Generator that can be programmed to
generate sixteen of the most popular baud rates.
The TPUART also allows the bypassing of the
Baud Rate Generator by programming Mode
D
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
Select Register
3
Baud Rate
D
0
0
0
0
1
1
1
1
0
0
0
0
1
1
1
1
2
D
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
1
D
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
19.200
38.400
Baud
134.5
1200
1800
2000
2400
3600
4800
7200
9600
Rate
110
150
300
600
50
Theoretical
Frequency
16X Clock
Clock Frequency = 5.0688 MHz
0.8 kHz
2.152
115.2
153.6
307.2
614.4
1.76
19.2
28.8
32.0
38.4
57.6
76.8
2.4
4.8
9.6
Table 2 - 16X CLOCK
Frequency
16X Clock
7
0.8 kHz
Actual
2.1523
32.081
115.2
153.6
316.8
633.6
1.76
19.2
28.8
38.4
57.6
76.8
2.4
4.8
9.6
Register bit 3 to accept a 16X external clock.
The Baud Rate Generator will not assume any
given baud rate upon power up, therefore it
must be programmed as desired. The following
chart is based on a 5.0688 MHz CLOCK
frequency.
Percent
Error
0.016
0.253
3.125
3.125
Cycle %
50/50
50/50
50/50
50/50
50/50
50/50
50/50
50/50
50/50
50/50
50/50
50/50
50/50
48/52
50/50
50/50
Duty
Divisor
6336
2880
2356
2112
1056
528
264
176
158
132
88
66
44
33
16
8