XR17D158 Exar Corporation, XR17D158 Datasheet - Page 32

• Manufacturer Part Number: XR17D158
• Description: Eight-channel Pci-bus Uart
• Manufacturer: Exar Corporation

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PRELIMINARY
The 8 sets of UART configuration registers are decoded using address lines A8 to A11 as shown below.
Address lines A0 to A3 select the 16 registers in each channel. The first 8 registers are 16550 compatible with
EXAR enhanced feature registers located on the upper 8 addresses.
5.5
UART CHANNEL CONFIGURATION REGISTERS AND ADDRESS DECODING
A3 A2 A1 A0
0
0
0
0
0
0
0
0
0
0
1
1
1
A
DDRESS
0
0
0
0
0
0
1
1
1
1
0
0
0
0 1
1 0
0 0
0 0
0 1
0 1
1 0
1 1
0 0
0 1
1 0
1 1
0 0
T
ABLE
RHR - Receive Holding Reg
THR - Transmit Holding Register
DLL - Div Latch Low
DLM - Div Latch High
IER - Interrupt Enable Reg
ISR - Interrupt Status Reg
FCR - FIFO Control Reg
LCR - Line Control Reg
MCR - Modem Control Reg
LSR - Line Status Reg
reserved
MSR - Modem Status Reg
SPR - Scratch Pad Reg
FCTR
EFR - Enhanced Function Reg
TXCNT - Transmit FIFO Level Counter
TXTRG - Transmit FIFO Trigger Level
10: UART CHANNEL CONFIGURATION REGISTERS.
- Auto RS485 Delay
A11
0
0
0
0
1
1
1
1
A10
R
0
0
1
1
0
0
1
1
EGISTER
E
16550 C
NHANCED
A9
0
1
0
1
0
1
0
1
32
OMPATIBLE
UNIVERSAL (3.3V AND 5V) PCI BUS OCTAL UART
R
EGISTER
A8
0
0
0
0
0
0
0
0
UART C
S
R
ELECTION
Read/Write
Read/Write
Read/Write
Read/Write
Read/Write
Read/Write
Read/Write
Read/Write
Read-only
Write-only
Read-only
Write-only
Read-only
Write-only
Read-only
Write-only
Read-only
Write-only
EAD
0
1
2
3
4
5
6
7
HANNEL
/W
RITE
C
LCR[7] = 0
LCR[7] = 1
LCR[7] = 1
LCR[7] = 0
OMMENTS
XR17D158
REV. P1.0.0