XR16L2550 Datasheet, PDF (21/45 Pages) Exar Corporation – LOW VOLTAGE DUART WITH 16-BYTE FIFO

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REV. 1.0.0
XR16L2550
LOW VOLTAGE DUART WITH 16-BYTE FIFO
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
010
010
ISR
FCR
RD FIFOs FIFOs
0/
0/
INT INT INT INT
Enabled Enabled
Source Source Source Source
INT
INT _{Bit-3 Bit-2 Bit-1 Bit-0}
Source Source
Bit-5 Bit-4
LCR ≠ 0xBF
WR RXFIFO RXFIFO 0
Trigger Trigger
0
DMA TX
RX FIFOs
Mode FIFO FIFO Enable
Enable Reset Reset
011
LCR
RD/WR Divisor
Enable
Set TX Set Par-
Break
ity
Even
Parity
Parity
Enable
Stop
Bits
Word Word
Length Length
Bit-1 Bit-0
100
MCR RD/WR
0/
BRG
Pres-
caler
0/
IR Mode
ENable
0/
XonAny
Internal
Lopback
Enable
OP2#/
INT
Output
Enable
Rsvd RTS# DTR#
(OP1#) ^{Output Output}
Control Control
1 0 1 LSR RD RX FIFO THR & THR
RX
RX
RX
RX
RX
Global TSR Empty Break Fram- Parity Over- Data LCR ≠ 0xBF
Error Empty
ing Error run Ready
Error
Error
1 1 0 MSR RD
CD#
Input
RI#
Input
DSR#
Input
CTS# Delta Delta Delta Delta
Input CD# RI# DSR# CTS#
1 1 1 SPR RD/WR Bit-7 Bit-6 Bit-5 Bit-4 Bit-3 Bit-2 Bit-1 Bit-0
Baud Rate Generator Divisor
000
001
DLL RD/WR Bit-7
DLM RD/WR Bit-7
Bit-6
Bit-6
Bit-5
Bit-5
Bit-4
Bit-4
Bit-3
Bit-3
Bit-2
Bit-2
Bit-1
Bit-1
Bit-0
Bit-0
LCR[7] = 1
LCR ≠ 0xBF
Enhanced Registers
010
100
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
XON1 RD/WR Bit-7 Bit-6 Bit-5 Bit-4 Bit-3
Soft-
ware
Flow
Cntl
Bit-2
Bit-2
Soft-
ware
Flow
Cntl
Bit-1
Bit-1
Soft-
ware
Flow
Cntl
Bit-0
Bit-0
LCR=0XBF
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
3.1 Receive Holding Register (RHR) - Read- Only
See “Receiver” on page 12.
3.2 Transmit Holding Register (THR) - Write-Only
See “Transmitter” on page 11.
3.3 Interrupt Enable Register (IER) - Read/Write
21