SCD1284 INTEL [Intel Corporation], SCD1284 Datasheet - Page 131

• Manufacturer Part Number: SCD1284
• Description: IEEE 1284-Compatible Parallel Interface Controller with Two High-Speed Asynchronous Serial Ports
• Manufacturer: INTEL [Intel Corporation]

7.5.4
7.5.5
7.5.6
Datasheet
Register Name: MSVR2
Register Description: Modem Signal Value Register 2
Access: Read/Write
Register Name: RBPR
Register Description: Receive Baud Rate Period
Access: Read/Write
Register Name: RCOR
Register Description: Receive Clock Option
Access: Read/Write
DSR
Bit 7
Bit 7
Bit 7
X
Modem Signal Value Register 2
MSVR1 and MSVR2 provide information regarding the state of the modem input pins (DSR*,
CTS*, RI*, and CD*) and allows control of the modem output pins (DTR* and RTS*). A write to
any of the input bits has no effect. With the exception of the least-significant two bits, the registers
reflect identical data. The two are provided as a convenience for control of the modem output pins.
It is not necessary for host software to keep a copy of the current state of either when controlling
the other. The actual signal level on the output is the inverse of the value placed in this register. For
example, setting the DTR bit causes the DTR output to become active-low. The state of the modem
input pins is also the inverse of the value in the corresponding bit in the registers.
Receive Baud Rate Period Register
This register holds the baud rate divisor for the receiver. It is used in conjunction with the RCOR.
This provides the clock, which is divided by this value. The time period produced must equal the
value for one bit time of the receive data.
Receive Clock Option Register
The RCOR selects the clock source, which drives the RBPR. The value in ClkSel2–ClkSel0 selects
one of five possible clocks generated from the master clock (CLK).
Bit 6
Bit 6
CTS
Bit 6
X
ClkSel2
0
0
0
0
1
Bit 5
Bit 5
Bit 5
RI
X
ClkSel1
0
0
1
1
0
IEEE 1284-Compatible Parallel Interface Controller — CD1284
Bit 4
Bit 4
Binary Divisor Value
Bit 4
CD
X
ClkSel0
0
1
0
1
0
Bit 3
Bit 3
Bit 3
X
0
Clk0 (CLK
Clk1 (CLK
Clk2 (CLK
Clk3 (CLK
Clk4 (CLK
ClkSel2
Bit 2
Bit 2
Bit 2
0
8)
32)
128)
512)
2048)
Clock Selected
ClkSel1
Bit 1
Bit 1
DTR
Bit 1
8-Bit Hex Address: 78
8-Bit Hex Address: 6D
8-Bit Hex Address: 7C
Default Value: 41
Default Value: XX
Default Value: 01
ClkSel0
Bit 0
Bit 0
Bit 0
0
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