XR18W750 Datasheet, PDF (18/44 Pages) Exar Corporation – WIRELESS UART CONTROLLER

XR18W750
WIRELESS UART CONTROLLER
REV. 1.0.0
4.0 UART INTERNAL REGISTERS
The internal registers of the UART are selected by address lines A2-A0 in the parallel mode. In the serial
mode, the UART registers are not accessible via these address lines. The 8051 microprocessor does not
access the enhanced UART in the parallel mode. The complete register set is shown on Table 7 and Table 8.
TABLE 7: UART INTERNAL REGISTERS
ADDRESS
A2 A1 A0
REGISTER
READ/WRITE
COMMENTS
16C550 COMPATIBLE REGISTERS
000
RHR - Receive Holding Register
THR - Transmit Holding Register
Read-only
Write-only
LCR[7] = 0
000
001
DLL - Divisor LSB
DLM - Divisor MSB
Read/Write
Read/Write
LCR[7] = 1, LCR ≠ 0xBF
000
001
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
010
ISR - Interrupt Status Register
FCR - FIFO Control Register
Read-only
Write-only
LCR ≠ 0xBF
011
LCR - Line Control Register
Read/Write
100
MCR - Modem Control Register
Read/Write
101
LSR - Line Status Register
Read-only
LCR ≠ 0xBF
110
MSR - Modem Status Register
Read-only
111
SPR - Scratch Pad Register
Read/Write LCR ≠ 0xBF, FCTR[6] = 0
111
111
FLVL - RX/TX FIFO Level Counter Register
EMSR - Enhanced Mode Select Register
Read-only
Write-only
LCR ≠ 0xBF, FCTR[6] = 1
ENHANCED REGISTERS
000
TRG - RX/TX FIFO Trigger Level Register
FC - RX/TX FIFO Level Counter Register
Write-only
Read-only
001
0 10
FCTR - Feature Control Register
EFR - Enhanced Function Register
Read/Write
Read/Write
LCR = 0xBF
1XX
Rsrvd
Read/Write
18