adc value not correct after a period of time.

[dty717]

CircuitPython version

Adafruit CircuitPython 7.3.3 on 2022-08-29; Raspberry Pi Pico with rp2040
Board ID:raspberry_pi_pico
boot.py output:

Code/REPL

import board
import busio
import digitalio
import analogio

import time
import pwmio

p1 = pwmio.PWMOut(board.GP18,frequency = 4000)
p1.duty_cycle = -1 + 2 ** 0
p2 = pwmio.PWMOut(board.GP19,frequency = 4000)
p2.duty_cycle = -1 + 2 ** 0
p3 = pwmio.PWMOut(board.GP20,frequency = 4000)
p3.duty_cycle = -1 + 2 ** 0
p4 = pwmio.PWMOut(board.GP21,frequency = 4000)
p4.duty_cycle = -1 +  2 ** 0


adc1 = analogio.AnalogIn(board.A0)
adc2 = analogio.AnalogIn(board.A1)
adc3 = analogio.AnalogIn(board.A2)

initWCS1800Val = 5/2 * 65535 / 3.3

K_WCS1800 = 60

def initWCS1800(adc,times = 1000):
    global initWCS1800Val
    initWCS1800SumTimes = times
    initWCS1800Val = 0
    while True:
        initWCS1800Val += adc.value
        initWCS1800SumTimes -= 1
        if initWCS1800SumTimes <= 0:
            break
    initWCS1800Val = initWCS1800Val / times
    return initWCS1800Val


def currentWCS1800(adc, times=1):
    global initWCS1800Val
    val = 0
    _times = times
    while _times > 0:
        val += adc.value
        _times -= 1
    return (val/times - initWCS1800Val) / 65535 * 3.3 / K_WCS1800*1000


initWCS1800(adc1)


initACS758Val = 3.3/2 * 65535 / 3.3

initACS758SumMaxTimes = 1000

K_ACS758 = 20

def initACS758(adc):
    global initACS758Val
    initACS758SumTimes = initACS758SumMaxTimes
    initACS758Val = 0
    while True:
        initACS758Val += adc.value
        initACS758SumTimes -= 1
        if initACS758SumTimes <= 0:
            break
    initACS758Val = initACS758Val / initACS758SumMaxTimes
    return initACS758Val


def currentACS758(adc):
    val = (adc.value - initACS758Val) / 65535 * 3.3
    return val/K_ACS758*1000

initACS758(adc2)


changeTimes = 50
step = 0
while True:
    time.sleep(0.02)
    # amp = v1()
    # voltage = adc1.value
    # (amp,voltage,amp*voltage)
    print((currentWCS1800(adc1,1000),adc1.value/65535))
    changeTimes -= 1
    if changeTimes <= 0:
        changeTimes = 200
        if step == 0:
            p1.duty_cycle = -1 + 2 ** 14
        elif step == 1:
            p1.duty_cycle = -1 + 2 ** 0
        elif step == 2:
            p2.duty_cycle = -1 + 2 ** 14
        elif step == 3:
            p2.duty_cycle = -1 + 2 ** 0
        step += 1
        step %= 4
        # time.sleep(2)
        # a.value = not a.value

Behavior

The adc value is 0.81 when running, but it changes to 0.82 after a period of time. When i restart the program the adc value return to 0.81. The adc value has a little shift that is not correct.

Description

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Additional information

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