5. Each Component Function
User’s Manual
63
Table 5.6. Function of Each Register < 4 / 4 >
MSR : Modem Status Register
D7
D6
D5
D4
D3
D2
D1
D0
03FEH
I/O address
Description
SCR : Scratchpad Register
03FFH
DCD RI
DSR CTS
DDCD TERI DDSR DCTS
Delta CTS
Delta DSR
Trailing edge RI
Delta data carrier detect
CTS
DSR
RI
DCD
This is an 8-bit, readable/writable register which is available to the user to
allow data to be saved temporarily.
Since these
statuses are
not used with
RS-485, data
is not valid.
Baud Rate Settings
A baud rate is set by software by dividing the clock input (1.8432MHz). The baud rate in terms of
hardware can be set to a maximum of 115,200 bps. The baud rates available in practice depend on the
operating environment (cable, software, etc.). The table below lists typical baud rates and their
respective values to be written to the divisor latch register (LSB, MSB).
Table 5.7. Baud Rate Settings
Baud rate to be set
Value to be set
in the divisor register
Setting error (%)
50
2304
---
75
1536
---
110
1047
0.026
134.5
857
0.058
150
768
---
300
384
---
600
192
---
1200
96
---
1800
64
---
2000
58
0.69
2400
48
---
3600
32
---
4800
24
---
7200
16
---
9600
12
---
19200
6
---
Example: To set 9,600 bps, write "00" to the (MSB) divisor latch register and "12 (decimal)" to the (LSB) divisor latch
register.
