xr
XR17C154
REV. 1.3.2
5V PCI BUS QUAD UART
33
.
TABLE 11: UART CHANNEL CONFIGURATION REGISTERS
ADDRESS
REGISTER
READ/WRITE
COMMENTS
A3
A2
A1
A0
16550 COMPATIBLE REGISTERS
0
RHR - Receive Holding Register
Read-only
LCR[7] = 0
0
THR - Transmit Holding Register
Write-only
LCR[7] = 0
0
DLL - Div Latch Low
Read/Write
LCR[7] = 1
0
1
DLM - Div Latch High
Read/Write
LCR[7] = 1
0
1
IER - Interrupt Enable Register
Read/Write
LCR[7] = 0
0
1
0
ISR - Interrupt Status Register
Read-only
0
1
0
FCR - FIFO Control Register
Write-only
0
1
LCR - Line Control Register
Read/Write
0
1
0
MCR - Modem Control Register
Read/Write
0
1
0
1
LSR - Line Status Register
Read-only
0
1
0
MSR - Modem Status Register
Read-only
0
1
0
RS485 Turn-Around Delay Register
Write-only
0
1
SPR - Scratch Pad Register
Read/Write
ENHANCED REGISTERS
1
0
FCTR - Feature Control Register
Read/Write
1
0
1
EFR - Enhanced Function Register
Read/Write
1
0
1
0
TXCNT - Transmit FIFO Level Counter
Read-only
1
0
1
0
TXTRG - Transmit FIFO Trigger Level
Write-only
1
0
1
RXCNT - Receive FIFO Level Counter
Read-only
1
0
1
RXTRG - Receive FIFO Trigger Level
Write-only
1
0
Xoff-1 - Xoff Character 1
Write-only
1
0
Xchar
Read-only
Xon,Xoff Rcvd. Flags
1
0
1
Xoff-2 - Xoff Character 2
Write-only
1
0
Xon-1 - Xon Character 1
Write-only
1
Xon-2 - Xon Character 2
Write-only