VS1053B Datasheet, PDF (49/79 Pages) List of Unclassifed Manufacturers – Ogg Vorbis/MP3/AAC/WMA/MIDI AUDIO CODEC

VLSI
Solution ^y
VS1053b preliminary
VS1053B
9. OPERATION
9.4 Low Power Mode
If you need to keep the system running while not decoding data, but need to lower the power consump-
tion, you can use the following tricks.
• Select the 1.0× clock by writing 0x0000 to SCI CLOCKF. This disables the PLL and saves some
power.
• Write a low non-zero value, such as 0x0010 to SCI AUDATA. This will reduce the samplerate and
the number of audio interrupts required. Between audio interrupts the VSDSP core will just wait
for an interrupt, thus saving power.
• Turn off all audio post-processing (tone controls and EarSpeaker).
• If possible for the application, write 0xffff to SCI VOL to disable the analog drivers.
To return from low-power mode, revert register values in reverse order.
Note: The low power mode consumes significantly more electricity than hardware reset.
9.5 Play and Decode
This is the normal operation mode of VS1053b. SDI data is decoded. Decoded samples are converted to
analog domain by the internal DAC. If no decodable data is found, SCI HDAT0 and SCI HDAT1 are set
to 0.
When there is no input for decoding, VS1053b goes into idle mode (lower power consumption than
during decoding) and actively monitors the serial data input for valid data.
9.5.1 Playing a Whole File
This is the default playback mode.
1. Send an audio file to VS1053b.
2. Read extra parameter value endFillByte (Chapter 9.11).
3. Send at least 2052 bytes of endFillByte[7:0].
4. Set SCI MODE bit SM CANCEL.
5. Send at least 32 bytes of endFillByte[7:0].
6. Read SCI MODE. If SM CANCEL is still set, go to 5. If SM CANCEL hasn’t cleared after
sending 2048 bytes, do a software reset (this should be extremely rare).
7. The song has now been successfully sent. HDAT0 and HDAT1 should now both contain 0 to
indicate that no format is being decoded. Return to 1.
Version 0.5, 2007-12-03
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