DM562AP
V.90 Integrated Data/ Fax/Voice/Speakerphone
Modem Device Single Chip with Memory Built in
Preliminary
21
Version: DM562AP-DS-P02
March 05, 2004
Modem Status Register (MSR): Address 6
Reset State bit 0-3 : low , bit 4-7: Input Signal
bit7 bit6 bit5 bit4 bit3
bit2 bit1
bit0
DCD RI
DSR CTS DDCD TERI DDSR DCTS
This 8-bit register provides the current state of the
control lines from the Modem to the CPU. In addition,
four bits of the Modem Status Register provide
change information. These bits are set to a logic 1
whenever a control input from the Modem changes
state. They are reset to logic 0 whenever the CPU
reads the Modem Status Register.
Bit 0: This bit is the Delta Clear to Send (DCTS)
indicator. Bit 0 indicates that the CTS (MSR Bit 4) has
changed state since the last time it was read by the
CPU.
Bit 1: This bit is the Delta Data Set Ready (DDSR)
indicator. Bit 1 indicates that the DSR (MSR Bit 5) has
changed state since the last time it was read by the
CPU.
Bit 2: This bit is the Trailing Edge of Ring indicator. Bit
2 indicates that the RI (MSR Bit 6) has changed from
a low to a high state.
Bit 3: This bit is the Delta Data Carrier Detect (DDCD)
indicator. Bit 3 indicates that the DCD (MSR Bti 7) has
changed state.
Note:Whenever bit 0, 1, 2 or 3 is set to a logic 1, a
Modem Status Interrupt is generated.
Bit 4: This bit reflects the value of MSR Bit 4 (CTS).
Bit 5: This bit reflects the value of MSR Bit 5 (DSR).
Bit 6: This bit reflects the value of MSR Bit 6 (RI).
Bit 7: This bit reflects the value of MSR Bit 7 (DCD).
Scratch Register (SCR): Address 7
Reset State 00h
This 8-bit Read/Write Register does not control the
UART in any way. It is intended as a Scratch Pad
Register to be used by the programmer to hold data
temporarily.
Divisor Latch (DLL): Address 0 (DLAB = 1)
Reset State 00h
bit7
bit6
bit5
bit4
bit3
bit2
bit1
bit0
DAT7 DAT6 DAT5 DAT4 DAT3 DAT2 DAT1 DAT0
This register contains baud rate information from the
host PC. The PC sets the Divisor Latch Register
values.
Divisor Latch (DLM): Address 1 (DLAB = 1)
Reset State 00h
bit7
bit6
bit5
bit4
bit3
bit2
bit1
bit0
DAT7 DAT6 DAT5 DAT4 DAT3 DAT2 DAT1 DAT0
This register contains baud rate information from the
host PC.
Note:Two 8-bit latches (DLL-DLM) store the divisor in
16-digit binary format. The desired baud rate can be
obtained by dividing the 115200Hz clock by the
divisor.
Desired
Baud Rate
Divisor
Value
50
2304
75
1536
110
1047
150
768
300
384
600
192
1200
96
2400
48
4800
24
9600
12
19200
6
38400
3
57600
2
115200
1
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