Reading linear hall effect sensor and converting it to linear displacement on RP2040 mPython

raw_hall.py

from machine import Pin, ADC
from time import sleep
from math import sqrt

pin = Pin(26)
adc = ADC(pin)

val = 0
margin = (2**8)

precal_maxval = 147

precalc = [0] * precal_maxval
for i in range(precal_maxval):
    precalc[i] = sqrt(i / precal_maxval)

while True:
    partial0 = adc.read_u16()
    partial1 = adc.read_u16()
    reading = (partial0 + partial1) // 2

    # reading = adc.read_u16()

    if reading + margin < val:
        val = reading + margin
    elif reading - margin > val:
        val = reading - margin
    else:
        sleep(0.02)
        continue

    val = (val >> 7) - 2 ** 8
    if val < 0:
        val = 0
    if val >= precal_maxval:
        val = precal_maxval - 1

    # a = val / maxval
    # a = sqrt(a)

    # cut away noisy area
    if val < 5:
        val = 0

    a = precalc[val]
    b = 1.0 - a

    print("#" * int(a * precal_maxval) + "_" * int(b * precal_maxval) + " " + repr(precal_maxval) + " ", end="\r")
    sleep(0.02)