Article: NuttX RTOS for PinePhone: Feature Phone UI in LVGL, Zig and WebAssembly

[lupyuen]

But how would I find more information on how the microphone is connected, and how those pins relate to the modem chip you described in another article with the PCM configuration information?

Yep it looks complex, let's walk through the connections:

1. The LTE Modem is connected to A64 Port PCM0 for PCM Audio
   
2. A64 Port PCM0 is documented in the A64 User Manual, "I2C/PCM", Page 621
   
3. So we need to route the PCM Audio from PCM0 to PinePhone's Microphone / Speaker
   

According to the PinePhone Schematic:

1. The Audio Connections are HPOUT, MIC1 (MICIN1), MIC2 (MICIN2), EAROUT, LINEOUT
   
2. HPOUT and MIC2 (MICIN2) are connected to Headphone Jack
   
3. MIC1 (MICIN1) is connected to the Digital Video Connector (?)
   
4. EAROUT is connected to the Earpiece Speaker
   
5. LINEOUT is connected to the Loudspeaker
   

A64 Ports HPOUT, MICIN1, MICIN2, EAROUT, LINEOUT are documented in the A64 User Manual, "Audio Codec", Page 278

I hope this will get you started :-)

To fix the DMB issue, we need to flush the CPU Cache.