VLSI
Solution
y
VS1103b
VS1103B
6. FUNCTIONAL DESCRIPTION
6.3 Data Flow of VS1103b
6.3.1 Normal Data Flow
Buffer 1
Buffer 2
Mixer
Gain 2
Gain 3
Gain 1
Audio stream
SCI
Buffer 3
* Only one MIDI and one ADPCM stream may be active at the time
**UART can only be used for real−time MIDI
SM_RECORD_PATH=1
encode
ADPCM
SM_ADPCM=1
SM_RECORD_PATH=0
GAIN3 != 0
UART
SCI
SDI
ADPCM stream
MIDI stream
Stream 4
SM_ICONF
AGC/Gain 4
A/D stream
A/D
44.1 kHz
8 kHz
Figure 12: Normal Data Flow of VS1103b, Part 1.
Generation of the Audio stream and recording A/D stream is presented in Figure 12.
Stream 1, which is the MIDI stream, may be fed either through SDI, SCI or UART. If it is fed through
UART, real-time MIDI, or RT-MIDI is assumed. The buffer size is 1024 bytes.
Stream 2, which is the ADPCM stream, may be fed either through SDI or SCI. The buffer size is 1024
bytes.
Stream 3, which is the A/D stream, running always at 8 kHz, is active if register SM ADPCM is set.
The outputs of the three streams are forwarded to the Mixer, which resamples all data to 44.1 kHz, and
forwards the data.
Either one of the A/D stream and the output of the Mixer can be fed to ADPCM encoding. If the data
is read from the A/D stream, it will be encoded as 8 kHz mono and if it is read from the Mixer, it will
encode as 44.1 kHz mono. The ADPCM compressed data may be read from SCI registers SCI IN0 and
SCI IN1. The buffer size is 1024 bytes.
Version 1.01, 2007-09-03
26
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