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#
# Author: peppe8o
# Date: Sep 24th, 2022
# Version: 1.0
# blog: https://peppe8o.com

# Please rename to "main.py" this script if you want to run it witout a connected PC
# Requires the ssd1306 library

from machine import Pin, I2C, ADC
from utime import sleep
import ssd1306

# setup the I2C communication with the OLED display
i2c = I2C(0, sda=Pin(16), scl=Pin(17))
display = ssd1306.SSD1306_I2C(128, 64, i2c)

# setup the ADC reading pin
Vin=ADC(26)

# the following function will run when no batteries are detected
def open_circ():
    display.text('-BATTERY TESTER-', 0, 0)
    display.text('Ready to test...', 0, 16)
    display.show()

# the following function return the read voltage if a battery is detected 
def measuring(adc_16_read):
    display.text('-BATTERY TESTER-', 0, 0)
    display.text('Measuring...', 0, 16)
    read_voltage=3.3*adc_16_read/65535
    read_voltage=round(read_voltage,2)
    display.text('Vin = '+str(read_voltage)+'V', 0, 32)
    display.show()


# main program
# defines the board noise threshold. Under this value, no batteries are detected
noise = 2000

while True:
    try:
        reading = Vin.read_u16()
        # for debug purposes, you can uncomment the following print statement
        #print(str(reading))
        display.fill(0)
        if reading < noise:
            open_circ()
        else:
            measuring(reading)
        sleep(1)
    except OSError as e:
        machine.reset()