3-4
Signals
Final Rev F
Copyright 1996 by LSI Logic Corporation. All rights reserved.
READ
Read/Write Strobe
Input
When READ is LOW, the host writes to the decoder.
When READ is HIGH, the host reads from the decoder.
READ is ignored in cycles in which VVALID or AVALID is
LOW when in parallel stream mode.
WAIT
Wait
3-State Output
When WAIT is asserted LOW during read access, it indi-
cates that the decoder’s host interface is still busy trans-
ferring data. Otherwise, the L64005 3-states the WAIT
signal. A pull-down resistor is required for this signal.
3.2
Channel
Interface
This section describes the signals that comprise the channel interface.
The channel interface receives the coded MPEG bitstream data from the
upstream device. The channel interface can receive data in serial or par-
allel format. Serial and parallel write requests are also described in this
section, following the signal descriptions.
AREQ
Audio Transfer Request
Output
When AREQ is asserted LOW, it indicates that the
decoder is ready to receive a new byte of coded audio
data (or system data in system mode). The decoder is
considered ready when both the interface is ready and
there is room in the audio channel buffer. If this is not true
AREQ will not be asserted. The maximum transfer rate
over this interface is 27 Mbits/s in serial mode, and 40
Mbits/s in parallel mode.
AVALID
Audio Data Valid
Input
In serial stream mode, the serial clock writes the next bit
of audio or system data into the chip if AVALID is
asserted HIGH. In parallel stream mode, the rising edge
of AVALID writes the next byte of audio or system data.
ERROR
Error
Input
When ERROR is asserted, it indicates that the channel
data has an error. In parallel stream mode it is latched
with the data on the rising edge of AVALID or VVALID. In
serial stream mode, ERROR is latched on the rising edge
of SCLKI if either AVALID or VVALID is also asserted
HIGH. ERROR is used to signal uncorrectable errors in
the channel, and is subsequently used to invoke error
handling in the decoder.