VS1003 is a single-chip MP3/WMA/MIDI audio decoder and ADPCM encoder. It contains a highperformance,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.
VS1003 receives its input bitstream through a serial
input bus, which it listens to as a system slave.
The input stream is decoded and passed through a
digital volume control to an 18-bit oversampling,multi-bit, sigma-delta DAC. The decoding is controlled via a serial control bus. In addition to the basic decoding, it is possible to add application specific features, like DSP effects, to the user RAM memory.