DM562P
V.90 Integrated Data/ Fax/Voice/Speakerphone
Modem Device Single Chip with Memory Built in
Modem Status Register (MSR): Address 6
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.
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.
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.
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.
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
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.
This register contains baud rate information from the
host PC.
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.
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.
Bit 3:This bit is the Delta Data Carrier Detect (DDCD)
indicator. Bit 3 indicates that the DCD (MSR Bti 7)
has changed state.
Desired
Baud
Rate
50
75
110
150
300
600
1200
2400
4800
9600
19200
38400
57600
115200
Divisor
Value
Note:Whenever bit 0, 1, 2 or 3 is set to a logic 1, a
Modem Status Interrupt is generated.
2304
1536
1047
768
384
192
96
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).
48
24
12
6
3
2
1
Final
21
Version: DM562P-DS-F01
February 02, 2004
DAVICOM [ DAVICOM SEMICONDUCTOR, INC. ]
