XR17D154 Datasheet, PDF (35/69 Pages) Exar Corporation – UNIVERSAL (3.3V AND 5V) PCI BUS QUAD UART

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REV. 1.2.0
XR17D154
UNIVERSAL (3.3V AND 5V) PCI BUS QUAD UART
Address lines A0 to A3 select the 16 registers in each channel. The first 8 registers are 16550 compatible with
the EXAR enhanced feature registers located on next 8 addresses locations. Addresses 0x080 to 0x093
comprise the Device Configuration Registers and they reside in Channel 0’s space.
.
TABLE 12: UART CHANNEL CONFIGURATION REGISTERS
ADDRESS
REGISTER
READ/WRITE
COMMENTS
A3 A2 A1 A0
16550 COMPATIBLE REGISTERS
0 0 0 0 RHR - Receive Holding Register
Read-only
LCR[7] = 0
0 0 0 0 THR - Transmit Holding Register
Write-only
LCR[7] = 0
0 0 0 0 DLL - Div Latch Low
Read/Write
LCR[7] = 1
0 0 0 1 DLM - Div Latch High
Read/Write
LCR[7] = 1
0 0 0 1 IER - Interrupt Enable Register
Read/Write
LCR[7] = 0
0 0 1 0 ISR - Interrupt Status Register
Read-only
0 0 1 0 FCR - FIFO Control Register
Write-only
0 0 1 1 LCR - Line Control Register
Read/Write
0 1 0 0 MCR - Modem Control Register
Read/Write
0 1 0 1 LSR - Line Status Register
Read-only
0 1 1 0 MSR - Modem Status Register
Read-only
0 1 1 0 RS485 Turn-Around Delay Register
Write-only
0 1 1 1 SPR - Scratch Pad Register
Read/Write
ENHANCED REGISTERS
1 0 0 0 FCTR - Feature Control Register
Read/Write
1 0 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 1 RXCNT - Receive FIFO Level Counter
Read-only
1 0 1 1 RXTRG - Receive FIFO Trigger Level
Write-only
1 1 0 0 Xoff-1 - Xoff Character 1
Write-only
1 1 0 0 Xchar
Read-only
Xon,Xoff Rcvd. Flags
1 1 0 1 Xoff-2 - Xoff Character 2
Write-only
1 1 1 0 Xon-1 - Xon Character 1
Write-only
1 1 1 1 Xon-2 - Xon Character 2
Write-only
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