VS1103/VS1103b pdf datasheet (

VS1103b is a single-chip MIDI/ADPCM/WAV audio
decoder and ADPCM encoder that can handle
upto three simultaneous audio streams. It can also
act as a Midi synthesizer.
VS1103b contains a high-performance, proprietary
low-power DSP processor core VS DSP4, working
data memory, 5 KiB instruction RAM and
0.5 KiB data RAM for user applications, serial
control and input data interfaces, 4 general purpose
I/O pins, an UART, as well as a high-quality
variable-sample-rate mono ADC and stereo DAC,
followed by an earphone amplifier and a common
buffer.
VS1103b receives its input bitstreams through serial
input buses, which it listens to as a system
slave. The input streams are decoded and passed
through digital volume controls to an 18-bit oversampling,
multi-bit, sigma-delta DAC. Decoding
is controlled via a serial control bus. In addition
to basic decoding, it is possible to add application
specific features, like DSP effects, to user RAM memory.