cs49329 Cirrus Logic, Inc., cs49329 Datasheet - Page 71

• Manufacturer Part Number: cs49329
• Description: Multi-standard Audio Decoder Family
• Manufacturer: Cirrus Logic, Inc.

delivering data. If using I2C or SPI control, then
parallel delivery can still be used using CMPCLK
and GPIO[7:0].
10.4.1.Parallel Delivery with Parallel
If using the Intel or Motorola Parallel host interface
mode, the system designer can also choose to
deliver data through the byte wide parallel port.
The delivery mechanism is identical to that
discussed
Communication” on page
The compressed data input register (CMPDAT)
receives bytes of data when the host interface
writes to address 11b (A1 and A0 are both high).
The host should check level of the Compressed
Data FIFO before sending data. The CS493XX has
two means of indicating the Compressed Data
FIFO level. The MFB bit in the Host Control
Register is one indicator of the Compressed Data
FIFO level. The MFB bit remains low until the FIFO
threshold has been reached. The alternative is to
use the CMPREQ pin of the CS493XX. The
CMPREQ pin also remains low until the FIFO
threshold has been reached. The host has the
option of using either CMPREQ or the MFB bit.
Data should be delivered to the CS493XX in blocks
of data. Before each block is delivered, the host
should check the MFB bit (or the CMPREQ pin). If
the MFB bit (CMPREQ) is low, then the host can
deliver a block of data one byte at a time. If the
MFB bit (CMPREQ) is high, no more data should
be sent to the CS493XX. Once the MFB bit
(CMPREQ) has gone low again, the host may send
another block of compressed audio data.
During delivery of a block of data the FIFO
threshold should not be checked. In other words
the FIFO indicators are level sensitive and indicate
that a block can be delivered when they are low.
They may return high during the data delivery.
When this happens there is still room for the
remaining bytes of the block.
The PCM data input register (PCMDAT) receives
bytes of data when the host interface writes to
address 10b (A1 high, A0 low). The MFC bit in the
Host Control Register is an indicator of the PCM
DS339F7
Control
in
Section
44.
6.2,
“Parallel
Host
FIFO level. The MFC bit remains low until the FIFO
threshold has been reached.
The PCMRST bit of the CONTROL register
provides
synchronization by initializing the input channel to
uniquely recognize the first write to the byte-wide
PCMDATA port. Toggling PCMRST high and low
informs the DSP that the next sample read from
the PCMDATA port is the first sample of the left
channel. In this fashion, the CS493XX can
translate successive byte writes into a variable
number of channels with a variable PCM sample
size. In the most simple case, the CS493XX can
receive stereo 8-bit PCM one byte at a time with
the internal DSP assigning the first 8-bit write (after
PCMRST) to the left channel and the second 8-bit
write to the right channel. For 24-bit PCM, it
assigns the first three 8-bit writes (after PCMRST)
to the left channel and the next three writes to the
right channel. Before starting PCM transfer, or to
initiate a new PCM transfer, the PCMRST bit must
be toggled as described above to insure data
integrity.
Data must be delivered to the CS493XX in blocks
of data. The block size is set through a hardware
configuration message. Before each block is
delivered, the host should check the MFC bit. If the
MFC bit is low, then the host can deliver a block of
data one byte at a time. If the MFC bit is high, no
more data should be sent to the CS493XX. Once
the MFC bit has gone low again, the host may send
another block of PCM audio data. The MFC bit is
FIFO level sensitive. In other words, it may change
during the transfer of a block. The host should
complete the block transfer and ignore the MFC bit
until the block transfer is complete.
10.4.2.Parallel Delivery with Serial
When using I
data
SCLKN2(CMPCLK) and GPIO[8:0]. In this mode
the bytewide parallel data is clocked into the part
on the transition of CMPCLK.
In this mode CMPREQ can be used as the FIFO
threshold indicator. When CMPREQ is low it
means that the CS493XX can receive another
block of data.
Control
can
2
C or SPI control, bytewide delivery of
absolute
still
CS49300 Family DSP
be
achieved
software/hardware
using
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