FLY E185
Service Manual
3.4.4 Audio frequency circuit
The audio front-end essentially consists of voice and audio data paths. Figure 128shows the block
diagram of the audio front-end. All voice band data paths comply with the GSM 03.50
specification. Mono hands-free audio or external FM radio playback paths are also provided. The
audio stereo path facilitates CD-quality playback, external FM radio, and voice playback through
a headset.
Block diagram of audio front-end
Figure 129 shows the digital circuits block diagram of the audio front-end. The APB register block
is an APB peripheral that stores settings from the MCU. The DSP audio port (DAP) block
interfaces with the DSP for control and data communications. The digital filter block performs
filter operations for voice band and audio band signal processing. The Digital Audio Interface
(DAI) block communicates with the System Simulator for FTA or external Bluetooth modules.
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