XR16C872IQ View Datasheet(PDF) - Exar Corporation
Part Name
Description
MFG CO.
'XR16C872IQ' PDF : 60 Pages View PDF
Preliminary
XR16C872
RLE
The module does not support Run Length Encoding
(RLE) compression (indicated by the “0” in CONF-B bit
7) but does support RLE de-compression on the receiv-
ing side.
The host may send compressed data to the peripheral
by writing the RLE length byte (bit 7 = 0) to address 000
(NOTE: DMA cannot be used for this byte) which will
place a zero into the FIFO tag bit. This must be
followed immediately by the data byte being written to
the FIFO at address 400. These bytes will be trans-
ferred to the peripheral in the normal manner.
De-compression takes place if PDIR = 1 when data is
read from the FIFO at address 000, 400 or DMA. When
a byte is read from the FIFO, bits 0-6 (length) are
placed in a counter if data bit-7 and the FIFO tag bit are
both low. The subsequent byte in the FIFO (data) is
presented to the host count + 1 times before the FIFO
read pointer is advanced.
A10 A2 A1 A0 Register
D7
D6
D5
D4
D3
D2
D1
D0
0 000
Data
PD7
ECP-AFIFO
PD6
PD5
PD4
PD3
PD2
PD1
PD0
0 001
DSR
Busy ACKE
PE
Select ERR#
1
1
1
0 010
DCR
0
0
DIR
INT SelectIN# INIT# AutoFD# Strobe#
enable
0 0 1 1 EPP-APort AP-7 AP-6 AP-5 AP-4 AP-3 AP-2
AP-1
AP-0
0 1 0 0 EPP-DPort PDA-7 PDA-6 PDA-5 PDA-4 PDA-3 PDA-2 PDA-1 PDA-0
0 1 0 1 EPP-DPort PDB-7 PDB-6 PDB-5 PDB-4 PDB-3 PDB-2 PDB-1 PDB-0
0 1 1 0 EPP-DPort PDC-7 PDC-6 PDC-5 PDC-4 PDC-3 PDC-2 PDC-1 PDC-0
0 1 1 1 EPP-DPort PDD-7 PDD-6 PDD-5 PDD-4 PDD-3 PDD-2 PDD-1 PDD-0
1 X 0 0 CONF-A
ECP
0
0
1
0
FIFO-F
0
0
INT type
1 X 0 1 CONF-B
RLE
IRQ
input
IRQ
Sel-2
IRQ
Sel-1
IRQ
Sel-0
DMA
Sel-2
DMA
Sel-1
DMA
Sel-0
1 X10
ECR
Mode
Sel-2
Mode
Sel-1
Mode Fault DMA Service
Sel-0 enable En/Dis INT
FIFO
full
FIFO
empty
Table 7. 1284 Control Register Description
Rev. P1.00
45
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