Firstly, thank you for your helpful answer !
If I understand you correctly, you wish to be able to connect an external audio source, to the "aux input" of the CSR8635, and have another IO that can switch between bluetooth and this AUX analogue input?
You're right, I want to use both Bluetooth and Aux Input. It means that I want to keep the Aux input plugged all the time, and select my source thanks to a manual switch.
Edit: just skimmed over the csr8635 datasheet, "wired mode" is when it routes the Line inputs (either lineA or line B) to the outputs when powered down. If you can find this setting in configuration, it means you can switch between bluetooth and its AUX input by powering the device down. I would follow this instructions in your link and see what happens, it really does look like it can switch the source using the IO, which is very handy. But the only way to know is to test. Find a pin on the bluetooth module that you don't use (isn't soldered to the main amp board) and use that for testing.
Exactly, I would like to try it. If you read the datasheet here (
https://electrothing.co.za/images/products/bluetooth-audio-module-8/CSR8635-datasheet.pdf) at the page 68, you will find an "Example Application Schematic".
On the top left corner, you can see the signal named "JACK_DET_PIO" which will change if an aux input is plugged.
It is linked to the pin "PIO[14] / UART_RX".
In that case, I assume that I can use the ROM Configuration Tools to configure the PIO[14] in the Input PIO's menu (see the link I sent in my previous post), and affect this PIO to the "Wired Input".
So, in my opinion the PIO[14] will be able to manage the switch between the Bluetooth and the Aux Input by simulating the Jack Detection in this PIO[14] input.
The PIO are defined as "programmable bidirectional I/O" by the datasheet.
In my opinion : According to this example application schematic, I think I need to link the manual switch directly to the PIO[14].
If the PIO is linked to the ground, so the aux input is considered as mated/plugged.
If the PIO is linked to nothing (open-circuit), so the aux input is considered as unmated/unplugged.
Do you think that my reasoning is right ? Thank you very much
Note : Sorry for my english, but I translated unmated as unplugged and mated as plugged, but I don't know if I'm right.
Note 2 : I will also mod my board as you recommended by removing some resistors in order to delete the noise