Damn, this took way too long. I am sorry everyone, I kept you waiting for almost a year and didn't really provide updates through these months (besides few ones on the Discord server). This year was though and the time I was able to put into this was very limited.
Anyways, I am finally done with this. The firmware is complete (although new features might be available in the future via upgrades) and it is very solid. This is a list of the features:
-Voltage regulation for the Wii
-1S battery pack charging with "charge & play"
-Integrated fuel gauge to monitor battery status (capacity, health, number of cycles, anything)
-On-board digital audio amp for speakers and headphones
-Fully configurable from the Wii through the companion homebrew
-Compatible both with momentary power switches and on-off switches
-PWM output to change LCD backlight brightness (requires mods to driver board)
-Temperature controlled fan driver thanks to a PID controller
-USB muxer selector (doesn't provide muxing feature by itself). Will explain better in another post
Protections:
-Thermal shutdown protection
-Low battery level shutdown
-Shipping mode
-WiiHUD compatibility to show stats (volume bar, battery percentage) on screen while playing any game
-Possibility to support expansion boards via i2c bus for things such as light sensor for automatic backlight control
-Fully upgradeable firmware from the Wii
-Fast, easy and safe
It will also come with this tiny board that sits right between the CPU and the GPU and provides accurate temperature readings from them.
I will be out of town until the end of the month, but after that I will assemble all the boards for the first batch (I have only done 6 as of now) and I will DM each one of you to sort out the details for the shipping.
Sorry again for the very long wait.