ANC Support

This is here to track our progress on enabling ANC in this open source firmware for the Pinebuds Pro.

Before I go into this; note I have no idea what I'm doing. This is all really guess and check.
Audio processing like this is new to me; so I'm coming really with no knowledge.

All work for this I'm tracking the anc-testing branch

I've been messing around this on and off and here is my notes so far:

• Set up the correct hardware channels to use correct mics (I hope)
• Hook up ANC button trigger on/off to long press on buds
• Allow enable/disable on any bud [Should work but doesn't, needs debug]
• Disable that damn Du-Du / Dun-Dun noise
• Get the ANC engine to activate
• Get reasonably usable results

Current status

Activating works on whatever bud is the primary for the TWS link; but it does sync the enable to the other bud correctly.
On activation you hear the Du-Du noise.
Then It does do something. I think it does like the worlds most mild ANC; but my testing is limited thus far.

Not certain what next steps are here; we may need to figure out tuning.

Tempted to start looking to pull apart binary dumps from existing bud backups but tracking here for ideas.

Please If you have ideas or do testing etc I'm keen to hear about it.

Start by reviewing the anc-testing branch and reproducing ANC activation on the PineBuds Pro hardware. Trace the existing hardware-channel setup, button trigger, and bud-to-bud enable behavior, then investigate the activation noise and ANC effectiveness. Done means ANC can be enabled reliably on either bud without the Du-Du noise and produces reasonably usable results.