Figure 51: Analogue Audio Reference Schematic
2.19.3 Unused Analogue Audio Signal Termination
The unused analogue audio signals can be left unconnected. Please note, even if the analogue
audio interface is not used at all, the analogue 3.3V power pins of the module (pin 314 and 320)
still needs to be powered. Alternatively, the analogue power can be connected to the digital 3.3V
power rail.
2.20 Digital Audio
The digital audio interface can be used for connecting additional audio codecs on the carrier board
or for other compatible audio equipment (e.g. DSP, Bluetooth adapter etc.). There are different
audio codec standards available, such as, I2S, AC’97, or HDA. Check the corresponding
datasheets of the modules for the information which codec standards are supported. The I2S is the
most likely to be compatible between different modules. Beside the standards, some modules
might also have additional proprietary interfaces available.
2.20.1 Digital Audio Signals
Table 32: Digital Audio Signals
2.20.2 Reference Schematics
The supported audio codec interface standards vary between the modules. The following reference
schematic shows the implementation of a HDA codec. Carefully check the direction of the signals.
For example, the Realtek ALC889 HDA audio codec names its data input signal as SDATA_OUT.
This means, the SDATA_OUT needs to be connected to the DAP1_D_OUT signal of the Apalis
module.
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