Specifications

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7. AUDIO INTERFACES
7.1 Audio Interface
The audio interface circuit consists of:
 Stereo audio CODEC
 Dual audio inputs and outputs
 A configurable PCM, I2S or SPDIF interface
Figure 13 outlines the functional blocks of the interface. The CODEC supports stereo
playback and recording of audio signals at multiple sample rates with a resolution of 16-
bit. The ADC and the DAC of the CODEC each contain two independent channels. Any ADC
or DAC channel can be run at its own independent sample rate.
Figure 13: Audio interface
The interface for the digital audio bus shares the same pins as the PCM CODEC interface
described in section 6.3,
which means that each of the audio buses are mutually exclusive
in their usage. Table 12 lists these alternative functions.
PCM Interface SPDIF Interface I2S Interface
PCM_OUT SPDIF_OUT SD_OUT
PCM_IN SPDIF_IN SD_IN
PCM_SYNC WS
PCM_CLK SCK
Table 12: Alternative functions of the digital audio bus interface on the PCM interface
7.1.1 Audio Input and Output
The audio input circuitry consists of a dual audio input that can be configured to be either
single-ended or fully differential and programmed for either microphone or line input. It
has an analogue and digital programmable gain stage for optimisation of different
microphones.
Audio signals are very sensitive to noise caused by the Bluetooth radio and it is highly
recommended to always use fully differential signals.
The audio output circuitry consists of a dual differential class A-B output stage.