XR16V2551 Datasheet, PDF (23/51 Pages) Exar Corporation – HIGH PERFORMANCE DUART WITH 16-BYTE FIFO AND POWERSAVE FEATURE

PRELIMINARY
XR16V2551
REV. P1.0.0
HIGH PERFORMANCE DUART WITH 16-BYTE FIFO AND POWERSAVE FEATURE
3.0 UART INTERNAL REGISTERS
Each of the UART channel in the V2551 has its own set of configuration registers selected by address lines A0,
A1 and A2 with CSA# or CSB# selecting the channel. The complete register set is shown on Table 9 and
Table 10.
TABLE 9: UART CHANNEL A AND B UART INTERNAL REGISTERS
ADDRESSES
A2 A1 A0
REGISTER
READ/WRITE
COMMENTS
16C550 COMPATIBLE REGISTERS
0 00
RHR - Receive Holding Register
THR - Transmit Holding Register
Read-only
Write-only
LCR[7] = 0
0 00
0 01
DLL - Divisor LSB
DLM - Divisor MSB
Read/Write
Read/Write
LCR[7] = 1, LCR ≠ 0xBF
0 10
DLD - Divisor Fractional
Read/Write
LCR[7] = 1, LCR ≠ 0xBF,
EFR[4] = 1
0 00
0 01
DREV - Device Revision Code
DVID - Device Identification Code
Read-only
Read-only
DLL, DLM = 0x00,
LCR[7] = 1, LCR ≠ 0xBF
0 01
IER - Interrupt Enable Register
Read/Write
LCR[7] = 0
0 10
ISR - Interrupt Status Register
FCR - FIFO Control Register
Read-only
Write-only
LCR ≠ 0xBF
0 11
LCR - Line Control Register
Read/Write
1 00
MCR - Modem Control Register
Read/Write
1 01
1 10
LSR - Line Status Register
MSR - Modem Status Register
Read-only
Read-only
LCR ≠ 0xBF
1 11
SPR - Scratch Pad Register
Read/Write
ENHANCED REGISTERS
0 10
EFR - Enhanced Function Register
Read/Write
1 00
Xon-1 - Xon Character 1
Read/Write
1 01
1 10
Xon-2 - Xon Character 2
Xoff-1 - Xoff Character 1
Read/Write
Read/Write
LCR = 0xBF
1 11
Xoff-2 - Xoff Character 2
Read/Write
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