LPC47M182 SMSC Corporation, LPC47M182 Datasheet - Page 107

• Manufacturer Part Number: LPC47M182
• Description: ADVANCED I/O CONTROLLER WITH MOTHERBOARD GLUE LOGIC
• Manufacturer: SMSC Corporation

Advanced I/O Controller with Motherboard GLUE Logic
Datasheet
7.12.4 CFIFO (Parallel Port Data FIFO)
7.12.5 ECPDFIFO (ECP Data FIFO)
7.12.6 tFifo (Test FIFO Mode)
SMSC LPC47M182
BITS 6 and 7 during a read are a low level, and cannot be written.
ADDRESS OFFSET = 400h
Mode = 010
Bytes written or DMAed from the system to this FIFO are transmitted by a hardware handshake to the
peripheral using the standard parallel port protocol. Transfers to the FIFO are byte aligned. This mode is
only defined for the forward direction.
ADDRESS OFFSET = 400H
Mode = 011
Bytes written or DMAed from the system to this FIFO, when the direction bit is 0, are transmitted by a
hardware handshake to the peripheral using the ECP parallel port protocol. Transfers to the FIFO are byte
aligned.
Data bytes from the peripheral are read under automatic hardware handshake from ECP into this FIFO
when the direction bit is 1. Reads or DMAs from the FIFO will return bytes of ECP data to the system.
ADDRESS OFFSET = 400H
Mode = 110
Data bytes may be read, written or DMAed to or from the system to this FIFO in any direction. Data in the
tFIFO will not be transmitted to the to the parallel port lines using a hardware protocol handshake.
However, data in the tFIFO may be displayed on the parallel port data lines.
The tFIFO will not stall when overwritten or underrun. If an attempt is made to write data to a full tFIFO,
the new data is not accepted into the tFIFO. If an attempt is made to read data from an empty tFIFO, the
last data byte is re-read again. The full and empty bits must always keep track of the correct FIFO state.
The tFIFO will transfer data at the maximum ISA rate so that software may generate performance metrics.
The FIFO size and interrupt threshold can be determined by writing bytes to the FIFO and checking the full
and serviceIntr bits.
The writeIntrThreshold can be determined by starting with a full tFIFO, setting the direction bit to 0 and
emptying it a byte at a time until serviceIntr is set. This may generate a spurious interrupt, but will indicate
that the threshold has been reached.
The readIntrThreshold can be determined by setting the direction bit to 1 and filling the empty tFIFO a byte
at a time until serviceIntr is set. This may generate a spurious interrupt, but will indicate that the threshold
has been reached.
Data bytes are always read from the head of tFIFO regardless of the value of the direction bit. For example
if 44h, 33h, 22h is written to the FIFO, then reading the tFIFO will return 44h, 33h, 22h in the same order
as was written.
DATASHEET
107
Revision 1.8 SMSC/Non-SMSC Register Sets (02-24-05)