mcs7717 MosChip, mcs7717 Datasheet - Page 25

• Manufacturer Part Number: mcs7717
• Description: Three Port Usb Hub With 1 Serial, 1 Printer
• Manufacturer: MosChip

Rev. 1.7
Modem Status Register:
This register provides the status of the modem control lines to CPU.
Register:
Description:
Offset:
Permissions:
Scratch Pad Register:
The scratch pad register does not effect operation of the rest of the UART in any way and can be used for the
temporary data storage.
Register:
Description:
Offset:
Permissions:
Bit
0
1
2
3
4
5
6
7
Bit[7]
Bit[7]
DCD
Trailing Edge
Delta DSR
Delta DCD
Delta CTS
Name
DCD
DSR
CTS
RI
RI
MSR
Modem Status Register
110
Read
SPR
Scratch Pad Register
111
Read/Write
Bit[6]
Bit[6]
RI
Logic 0 = no change in the CTS signal
Logic 1 = indicates that the CTS input has changed since the last time the
Logic 0 = no change in the DSR signal
Logic 1 = indicates that the DSR input has changed since the last time the
Logic 0 = no change in the RI signal
Logic 1 = indicates that the RI input has changed from low to high since the
Logic 0 = no change in the DCD signal
Logic 1 = indicates that the DCD input has changed since the last time the
Logic 0 = CTS# line is 1
Logic 1 = CTS# line is 0
Logic 0 = DSR# line is 1
Logic 1 = DSR# line is 0
Logic 0 = RI# line is 1
Logic 1 = RI# line is 0
Logic 0 = DCD# line is 1
Logic 1 = DCD# line is 0
Bit[5]
Bit[5]
DSR
MSR was read
MSR was read
last time the MSR was read
MSR was read
Scratch Pad Register
Bit[4]
Bit[4]
CTS
Three Port USB Hub with 1 Serial, 1 Printer
Delta DCD
Bit[3]
Bit[3]
Description
Edge RI
Trailing
Bit[2]
Bit[2]
MCS7717
Delta DSR Delta CTS
Bit[1]
Bit[1]
Bit[0]
Bit[0]
Page 25