VS1003 is a single-chip MP3/WMA/MIDI audio decoder and ADPCM encoder. It 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.

    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, sigmadelta 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.

Specifications:

• Decodes MPEG 1 & 2 audio layer III (CBR +VBR +ABR); WMA 4.0/4.1/7/8/9 all profiles (5-384kbit/s); WAV (PCM + IMA ADPCM); General MIDI / SP-MIDI files
• Encodes IMA ADPCM from microphone or line input
• Streaming support for MP3 and WAV
• Bass and treble controls
• Internal PLL clock multiplier
• Low-power operation
• High-quality on-chip stereo DAC with no phase error between channels
• Stereo earphone driver capable of driving a 30Ω load
• Separate operating voltages for analog, digital and I/O
• 5.5 KiB On-chip RAM for user code /data
• Serial control and data interfaces
• Can be used as a slave co-processor
• SPI flash boot for special applications
• UART for debugging purposes
• New functions may be added with software and 4 GPIO pins