nRF5340 Audio application onboard vs external hardware codec

Question

Hi 
 The documentation of nRF5340 Audio Application of nRF Connect SDK 2.1.1 mentions "onboard hardware codec" and "external hardware codec". 
 
 From https://developer.nordicsemi.com/nRF_Connect_SDK/doc/2.1.1/nrf/applications/nrf5340_audio/README.html#leds : 
 
 CODEC Off - No configuration loaded to the onboard hardware codec. 
 
 and 
 
 OB/EXT 
 Solid green - On-board hardware codec selected. 
 Solid yellow - External hardware codec selected. This LED turns solid yellow also when the devices are reset, for the time then pins are floating. 
 
 Is there some more description on how I can select either of the 3 LC3 codecs? 
 
 LC3 software codec (used in default configuration) 
 Onboard hardware codec 
 External hardware codec

Additionally, I'm not sure about what component is meant by "onboard hardware codec". What component is it? 
 
 Many thanks for bringing more light into that.

Chraebs · Accepted Answer

Hi Elfving 
 Ok, I see. It seems that I did not differentiate between the two functionalities which are addressed by the "Codecs". 
 
 The LC3 software codec is used for encoding/decoding audio for transceiving audio via Bluetooth LE Audio. 
 
 The Onboard/external codec is used for AD/DA conversion for transceiving audio to microphone/loudspeaker.

I thought there might be a suggested design for offloading LC3 encoding/decoding from nRF5340 - this is why I got confused before. 
 Thanks Elfving for the outline on how to select an external HW codec in your response.

nRF5340 Audio application onboard vs external hardware codec

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