How to configure LINE IN as the input

[MartinTsangNZ]

I am new to the ESP32 Audio Kit. I have searched through the documentation but cannot find how to configure the input.device to the LINE IN input.
From one of the examples, I know the following statement is used to set the input to the built-in microphone
cfg.input_device = ADC_INPUT_LINE2;

[pschatzmann]

All AudioKit using the ES8388 have a hardware bug, so this will not be possible!

The Line in and Microphones are always mixed together. As a work around make sure that the line in much louder to overpower the microphones...

It is a great device for output and microphone input. If you need a working board that provides the complete input functionality, use e.g. a LyraT

[ainst]

There is a way to make this work by correcting the hardware bug. I posted a comment to the blog post linked in @pschatzmann's reply above but will repeat it here for convenience.

TLDR; I can get perfectly working stereo line in and stereo microphones by moving two capacitors on the AIThinker AudioKit board.
On my board (V2.2 A247 ES8388), LINEINL (pin 22) and MIC1N (pin18) are connected together on the A1S module. Similarly, LINEINR (pin 21) and MIC2N (pin 14) are also connected on the module. These two pairs are routed to LIN2 and RIN2 on the ES8388 respectively.

Some capacitors were already removed on the AI Thinker board that I received, but they appear to be the wrong ones. C17 was removed which connects the left microphone to the MIC1P (pin 17 on the A1S, LIN1 on the ES8388) and C19 was removed which connects the right microphone to MIC2P (pin 15 on the A1S). I think the intention was to make the microphones single ended and remove the negative input. However, the effect was to disconnect the microphones from the LIN1 / RIN1 input, and at the same time leave them connected to the LIN2 / RIN2 inputs (which are also connected to the line in circuit). This is why there is no input on Input Line 1 and mixed microphones / line in audio on Input Line 2.

I moved capacitor C18 to the C17 position and C20 to the C19 position. This connects the microphones to the left and right channels of Input Line 1 and isolates them from the Input Line 2 / line in path. The fix works well on my board, and I can now use either stereo microphones, stereo line in, or mix both in software. See picture below for the component positions (some are removed in the photo as I was experimenting at the time).

[MartinTsangNZ]

Thank you for sharing your experience. I will try it.

[MartinTsangNZ]

At the moment, I use the following statement to set the input to the built-in microphone and LINE_IN
cfg.input_device = ADC_INPUT_LINE2;

Once they are separated, how should I define the input.device to address them individually?
I have tried ADC_INPUT_LINE1 and ADC_INPUT_LINE3; both are valid, but they do not connect the input to the mic or the line-in.

By the way, where can I find the full documentation for cfg.### ?