8. Serial Controller
83
Line Status Register
Register: Line Status
Address: 3FDh
Access: Read
0
TRB
THR
BRK
FRM PTY
OVR
RBR
7
6
5
4
3
2
1
0
Receive Buffer
0 Empty
1 Full
Overrun Error
0 No error
1 Error
Parity Error
0 No error
1 Error
Framing Error
0 No error
1 Error
Break Sequence
0 Not detected
1 Detected
Transmit Holding Register
0 Full
1 Empty
Transmit Buffer
0 Full
1 Empty
Line Status Register
Modem Control Register
7
6
5
4
3
2
1
0
Register: Modem Control
Address: 2FC/3FCh
Access: Read and Write
Data Terminal Ready
0 Negative voltage
1 Positive voltage
0
0
LBD
OUT2
0
RTS
DTR
Request To Send
0 Negative voltage
1 Positive voltage
0
Loop Back Diagnositcs
0 Disabled
1 Enabled
Output 2
0 RS 485 Disabled
1 RS 485 Enabled
Modem Control Register