VS1001K
VLSI
DATASHEET
y
Solution
8. OPERATION
8.5 Play/Decode
This is the normal operation mode of VS1001k. The SDI data is decoded. Decoded samples are converted
to analog domain by the internal DAC, If there are errors in the decoding process, the error flags of SCI’s
HDAT0 and HDAT1 are set accordingly. In case there are serious errors in the input data, decoding is
still continued, but the analog outputs are muted.
When there is no valid input for decoding, VS1001k goes into idle mode (lower power consumption than
during decoding) and actively monitors the serial data input for valid data. The data input does not need
to be clocked (DCLK) when no data is sent.
The software needs to be reset between MPEG audio stream files. See for the Chapter “Testing” to see
how it is done.
8.6 Sanity Checks
Although VS1001k checks extensively for bad MP3 streams, it may happen that it encounters a bitstream
that makes the firmware’s recovery code fail. This may particularly happen during fast forward and fast
backwards operations, where the data where the microcontroller lands the MP3 decoder may not be a
valid header.
The microcontroller should keep a look at the data speeds VS1001k requires. If data input either stops
completely (DREQ always inactive) for a whole second, or if VS1001k requires more than 60 KiB data
in any single second, it is the responsibility of the microcontroller to either reset the software. If that
doesn’t help, a hardware reset should be issued.
8.7 PCM Mode
VS1001k can be used as a Digital-to-Analog converter (DAC) by feeding PCM data. A convenient way
to use VS1001k as a DAC is to load SDI PCM Extension for VS1001k software from VLSI Solution’s
home page at http://www.vlsi.fi/vs1001/software/.
The SDI PCM Extension makes it possible for the user to use SDI to feed 8-bit or 16-bit PCM samples
in mono or stereo at any sample rate upto 48 kHz (with nominal 24.576 MHz operating frequency).
8.8 Testing
There are several test modes in VS1001k, which allow the user to perform memory tests, SCI bus tests,
and several different sine wave tests ranging from 250 Hz to 1500 Hz.
All tests are started in a similar way: VS1001 is hardware reset, and then a test command is sent to the
SDI bus. Each test is started by sending a 4-byte special command sequence, followed by 4 zeros. The
sequences are described below.
Version 4.11, 2003-09-18
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