capacitive touchpad, how they work in detail? want to be build one from scratch

[DiTBho]

is there any paper that describes in details how they work?

How to design the capacitive grid, what capacitance to operate with, how to measure a local change in capacitance with enough precision to generate a "mouse" event { delta_x, delta_y } when a finger put on a subarea of the grid and moved just a bit ...

and what algorithms you'd best use to filter and process ...

etc ...

I can use a BF537 DSP, I got an old dev board for free.

[DiTBho]

(
yes, I have already reverse engineered the protocol of a few touchpads with a Synaptics chip,
recovered from old broken laptops
but, ... umm, I prefer to make my own one.
I have absolutely ZERO idea about what the Synaptics chip does internally.
I just knows, what it communictates to the motherboard
)

[ledtester]

By coincidence, Electroboom just released this video two days ago:

The Touchscreen that Changed the World! -- Electroboom
https://youtu.be/u8s9hpjN25Y

He builds his own a capacitive touchscreen starting at 6:43.

[DiTBho]

The Touchscreen that Changed the World! -- Electroboom

He builds a capacitive 4x4 grid "touch-sensor".
As a summary description it's ok, but some details are missing.

Moving from capacitive "touch-sensor" to capacitive "touchpad", it's missing from the sizing to the algorithmic part for filtering and extracting mouse events.