XR16L2750_05 Datasheet, PDF (22/48 Pages) Exar Corporation – 2.25V TO 5.5V DUART WITH 64-BYTE FIFO

XR16L2750
2.25V TO 5.5V DUART WITH 64-BYTE FIFO
xr
REV. 1.2.1
TABLE 8: INTERNAL REGISTERS DESCRIPTION. SHADED BITS ARE ENABLED WHEN EFR BIT-4=1
ADDRESS REG READ/
A2-A0 NAME WRITE
BIT-7
BIT-6
BIT-5
BIT-4
BIT-3 BIT-2 BIT-1 BIT-0 COMMENT
000
001
DLL RD/WR
DLM RD/WR
Bit-7
Bit-7
Baud Rate Generator Divisor
Bit-6 Bit-5 Bit-4
Bit-3
Bit-6 Bit-5 Bit-4
Bit-3
Bit-2
Bit-2
Bit-1
Bit-1
Bit-0 ^LCR[7]=1
LCR ≠ 0xBF
Bit-0
0 0 0 DREV RD
0 0 1 DVID RD
Bit-7
0
Bit-6
0
Bit-5
0
Bit-4
0
Bit-3
1
Bit-2
0
Bit-1
1
Bit-0
0
LCR[7]=1
LCR ≠ 0xBF
DLL=0x00
DLM=0x00
Enhanced Registers
0 0 0 TRG WR Bit-7 Bit-6 Bit-5 Bit-4
Bit-3 Bit-2 Bit-1 Bit-0
000
FC
RD Bit-7 Bit-6 Bit-5 Bit-4
Bit-3 Bit-2 Bit-1 Bit-0
001
FCTR RD/WR RX/TX SCPAD
Mode Swap
Trig
Table
Bit-1
Trig
Table
Bit-0
Auto
RS485
Direction
Control
RX IR
Input
Inv.
Auto
RTS
Hyst
Bit-1
Auto
RTS
Hyst
Bit-0
010
EFR
RD/WR Auto
CTS
Enable
Auto
RTS
Enable
Special
Char
Select
Enable
IER [7:4],
ISR [5:4],
FCR[5:4],
MCR[7:5]
Soft-
ware
Flow
Cntl
Bit-3
Soft-
ware
Flow
Cntl
Bit-2
Soft-
ware
Flow
Cntl
Bit-1
Soft-
ware
Flow
Cntl
Bit-0
LCR=0XBF
1 0 0 XON1 RD/WR Bit-7 Bit-6 Bit-5 Bit-4
Bit-3 Bit-2 Bit-1 Bit-0
1 0 1 XON2 RD/WR Bit-7 Bit-6 Bit-5 Bit-4
Bit-3 Bit-2 Bit-1 Bit-0
1 1 0 XOFF1 RD/WR Bit-7 Bit-6 Bit-5 Bit-4
Bit-3 Bit-2 Bit-1 Bit-0
1 1 1 XOFF2 RD/WR Bit-7 Bit-6 Bit-5 Bit-4
Bit-3 Bit-2 Bit-1 Bit-0
4.0 INTERNAL REGISTER DESCRIPTIONS
4.1 Receive Holding Register (RHR) - Read- Only
See “Receiver” on page 12.
4.2 Transmit Holding Register (THR) - Write-Only
See “Transmitter” on page 11.
4.3 Interrupt Enable Register (IER) - Read/Write
The Interrupt Enable Register (IER) masks the interrupts from receive data ready, transmit empty, line status
and modem status registers. These interrupts are reported in the Interrupt Status Register (ISR).
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