Making a simple stylus pen touchpad

This week (which is going to be submitted late), I'm planning to make a simple prototype for my final project idea of a portable notebook. It has a 4 horizontal and 4 vertical strips of copper tape wired into XIAO nRF52840 Sense board which has bluetooth for future applications. There's a pen connected to pin A0 and there's 100k ohm pull-up resistor and 10M ohm pull down resistor between the pin and pen to make the pen sensitive to voltage changes. The copper strips are given pulses in different times that map the location of the pen. This architecture was designed with Claude given the Rand Tablet as context and it made the following diagram of the solution.

I opened Getting started page for XIAO nRF52840 Sense and collected the copper tape, a transparent film as a surface to place them on on and some glued transparent epoxy plastic for an insulator between and on top of the copper strips. I cut 8 15mm wide 100mm long strips of copper tape and soldered 120mm wires to them before gluing them to plastic surface. The wires should be as short as possible to avoid them sensing "noise" electricity. They should also be the same length to get equal sensor input from each of them.

As I had the wires soldered, I placed the stripes on transparent film and began placing epoxy "tape" on top of them. Here I wanted to have all the air out under the epoxy, as it would disturb sensor input making it uneven. This wasn't fully possible but made my best with a flat tool that is used for vinyl cut weeding.

Then I place the second layer of strips. I become more and more convinced that it's impossible the calculate an accurate location based on these rather inconsistent copper strips, but let's see. Now I also remembered that the copper strips are also tape, but I hadn't taped the first layers.

I set the thing up with a bread board to test it quicker than by soldering things (and possibly resolder multiple times). The right resistor is 10M ohm and it's wire is connected to GND and the left is 100k ohm and is connected to 3.3V. In between is the pen wire.

Trying to set up the XIAO nRF52840 for MicroPython with these instructions, because I'm more adept in python than arduino-language. The problem I was struggling with that the firmware available has only flash.bat file which I caanot open with MacOs. So, I wasn't able the have the XIAO connected to Thonny.

I turned to CircuitPython, which was easy and quick setup: I downloaded CircuitPython .uf2-file from here and moved the file to the microcontroller folder. I had made it visible on my computer by double-clicking the reset button on the board. Then I copy-pasted the code by Claude to code.py file inside the XIAO board. Now I can get some numbers out, but they don't make much sense. Here are the input of values of one circular movement around the area.