Data Sheet

PRELIMINARY
VS1063a Datasheet
10 OPERATION
10.11.5 PCM Mixer
Parameter Address Usage
playMode 0x1e09 bit 4: PCM Mixer enable
pcmMixerRate 0x1e0f PCM mixer samplerate
pcmMixerFree 0x1e10 PCM mixer FIFO free state
pcmMixerVol 0x1e11 PCM mixer volume 0. . . 191 (-0.5 dB steps)
The PCM Mixer allows a mono 16-bit linear PCM stream be played back during any audio
format playback. Because the SDM audio side path does not have any interpolation, the PCM
audio is automatically upsampled to at least 22000 Hz to keep good audio quality.
The PCM samplerate is configured from , and it must be written before PCM
Mixer is enabled from the variable. With the nominal 12.288 MHz clock the sam-
plerates 8000 Hz, 12000 Hz, 16000 Hz, 24000 Hz, 32000 Hz, 48000 Hz are exact. You can use
other rates as well, but they are not exact (for example 11025 Hz, 22050 Hz and 44100 Hz play
0.23% too fast).
The PCM data is to be written to SCI_AICTRL0 register, and tells how much
space is in the PCM FIFO (you can send upto this many words). Note that SCI multiple write
can be used to write multiple words with minimal overhead.
controls volume independently of the normal playback volume. Values from 0
to 182 control PCM volume in 0.5dB steps. Note: to prevent sigma-delta modulator overflow,
SCI_VOL should be at least 2dB (0x0404), and the sum of SCI_VOL and attenu-
ations at least 6dB (12). If you have not set large enough attenuations, the PCM Mixer adjusts
the registers automatically to have at least these values. To have absolutely safe scaling, have
6dB (0x0c0c) or more in both SCI_VOL and .
The processing power needed depends on the samplerate, e.g. 8 kHz = 4.0MHz, 16 kHz =
6.8MHz, 24 kHz = 4.9MHz, 32 kHz = 6.5MHz.
Processing will be automatically disabled after a 0.125-second timeout when samples are not
being written to SCI_AICTRL0. The processing is resumed when there are at least 128 samples
in the PCM FIFO (1/4 full).
AD Mixer and PCM Mixer can not be on simultaneously. AD Mixer overrides PCM Mixer.
Version: 0.42, 2011-11-24 70