Acromag AcroPack AP513, User Manual

Page: 28 / 58

AP513 ACROPACK
USER
’S MANUAL
Acromag, Inc. Tel: 248-295-0310 - 27 -
http://www.acromag.com
- 27 - www.acromag.com
RHR register when reading that address. Both THR and RHR registers are
16C550 compatible in 8-bit format, so each bus operation can only write or
read in bytes.
3.4 UART Channel Configuration Registers
There are 4 UARTs channel [3:0] in the XR17V354. Each has its own 256-byte
of transmit and receive FIFO, a set of 16550 compatible control and status
registers, and a baud rate generator for individual channel data rate setting.
Eight additional registers per UART were added for the EXAR enhanced
features.
Address lines A0 to A3 select the 16 registers in each channel. The first 8
registers are 16550 compatible with EXAR enhanced feature registers
located on the upper 8 addresses.
Table 3.8 UART Channel
Configuration Registers
A[3:0] Registers Read/Write Comments
16550 COMPATIBLE
0 0 0 0 RHR - Receive Holding Register
THR - Transmit Holding Register Read-only
Write-only
LCR[7]=0
0 0 0 0 DLL - Divisor LSB Read/Write LCR[7]=1
0 0 0 1 IER - Interrupt Enable Register Read/Write LCR[7]=0
0 0 0 1 DLM - Divisor MSB Read/Write LCR[7]=1
0 0 1 0 ISR - Interrupt Status Register
FCR - FIFO Control Register Read-only
Write-only
LCR[7]=0
0 0 1 0 DLD - Divisor Fractional Read/Write LCR[7]=1
0 0 1 1 LCR - Line Control Register Read/Write
0 1 0 0 MCR - Modem Control Register Read/Write
0 1 0 1 LSR - Line Status Register Read-only
0 1 1 0 MSR - Modem Status Register
-Auto RS485 Delay Read-only
Write-only EFR bit-4=1
0 1 1 1 SPR- Scratch Pad Register Read/Write
ENHANCED REGISTER
1 0 0 0 FCTR - Feature Control Register Read/Write
1 0 0 1 EFR - Enhanced Function Register Read/Write
1 0 1 0 TXCNT - Tx FIFO Level Counter
TXTRG - Tx FIFO Trigger Level Read-only
Write-only
1 0 1 1 RXCNT- Rx FIFO Level Counter
RXTRG
– Rx FIFO Trigger Level
Read-only
Write-only
1 1 0 0 Xoff-1 - Xoff Character 1
Xchar Write-only
Read-only
Xon,Xoff
Rcvd. Flags
1 1 0 1 Xoff-2 - Xoff Character 2 Write-only
1 1 1 0 Xon-1 - Xon Character 1 Write-only
1 1 1 1 Xon-2 - Xon Character 2 Write-only