Other I/O Interfaces

Beyond the 40-pin GPIO header, the KNEO Pi also features additional I/O interfaces, including:

• Audio Jack (3.5mm TRRS)
• MIPI Camera (CSI interface for image sensors)
• MIPI Display (DSI interface for LCD panels), not covered in KNEO Pi usage
• SDIO (for high-speed external devices), not covered in KNEO Pi usage

Using Audio

The KNEO Pi features a 3.5mm TRRS audio jack that supports both audio output and microphone input. To test audio functionality, you can use the arecord and aplay utilities for recording and playback.

1. Check Available Audio Devices

   • for PLAYBACK device

     $ aplay -l
     
     **** List of PLAYBACK Hardware Devices ****
     card 0: EVM [VTX EVM], device 0: vtx-stream inno-hifi-0 []
       Subdevices: 1/1
       Subdevice #0: subdevice #0
     

   • for CAPTURE device

     $ arecord -l
     
     **** List of CAPTURE Hardware Devices ****
     card 0: EVM [VTX EVM], device 0: vtx-stream inno-hifi-0 []
       Subdevices: 1/1
       Subdevice #0: subdevice #0
     

2. Audio loopback(Recording/Playback) Test

   To test the audio input and output together, record and immediately play back the captured audio in a single command:

   $ arecord -D hw:0,0 -r 8000 -c 2 -f S16_LE | aplay -D "hw:0,0" -r 8000 -c 2 -f S16_LE
   
   Recording WAVE 'stdin' : Signed 16 bit Little Endian, Rate 8000 Hz, Stereo
   Playing WAVE 'stdin' : Signed 16 bit Little Endian, Rate 8000 Hz, Stereo
   

ALSA Project Offiicial website reference

For more details on using ALSA tools and developing audio applications, visit the ALSA Project's official website: https://www.alsa-project.org. There, you can find documentation on command-line utilities, programming guides, and API references for integrating audio functionality into your applications.

Using MIPI camera

The KNEO Pi supports some MIPI cameras with built-in driver support. Limited usage examples are provided through the following:

• example_nnm_sensor: Captures images from MIPI sensor and integrates AI inference
• example: video encoding: Caputures images from MIPI sensor and excodes using a specified codec.

For detailed control and advanced functionality, refer to the Full-Function SDK, which provides in-depth configuration options, sensor tuning, and extended capabilities.