XR16C2552 Datasheet, PDF (15/36 Pages) Exar Corporation – 2.97V TO 5.5V DUAL UART WITH 16-BYTE FIFO

xr
REV. 1.0.0
XR16C2552
2.97V TO 5.5V DUAL UART WITH 16-BYTE FIFO
3.0 UART INTERNAL REGISTERS
Each of the UART channel in the 2552 has its own set of configuration registers selected by address lines A0,
A1 and A2 with CS# and CHSEL selecting the channel. The registers are 16C550 compatible. The complete
register set is shown in Table 6 and Table 7.
TABLE 6: UART CHANNEL A AND B UART INTERNAL REGISTERS
A2,A1,A0 ADDRESSES
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
DLL - Div Latch Low Byte
Read/Write
LCR[7] = 1
0 01
DLM - Div Latch High Byte
Read/Write
LCR[7] = 1
0 10
AFR - Alternate Function Register
Read/Write
LCR[7] = 1
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[7] = 0
0 11
LCR - Line Control Register
Read/Write
1 00
MCR - Modem Control Register
Read/Write
1 01
LSR - Line Status Register
Reserved
Read-only
Write-only
1 10
MSR - Modem Status Register
Reserved
Read-only
Write-only
1 11
SPR - Scratch Pad Register
Read/Write
15