# This example reads the voltage from a LiPo battery connected to Pimoroni Pico LiPo
# and uses this reading to calculate how much charge is left in the battery.
# It then displays the info on the screen of Pico Display (or Pico Display 2.0).
# With Pimoroni Pico LiPo, you can read the battery percentage while it's charging.
# Save this code as main.py on your Pico if you want it to run automatically!

from machine import ADC, Pin
import time
# change to DISPLAY_PICO_DISPLAY_2 for Pico Display 2.0
from picographics import PicoGraphics, DISPLAY_PICO_DISPLAY

display = PicoGraphics(display=DISPLAY_PICO_DISPLAY, rotate=0)

display.set_backlight(0.8)

vsys = ADC(29)                      # reads the system input voltage
charging = Pin(24, Pin.IN)          # reading GP24 tells us whether or not USB power is connected
conversion_factor = 3 * 3.3 / 65535

full_battery = 4.2                  # reference voltages for a full/empty battery, in volts
empty_battery = 2.8                 # the values could vary by battery size/manufacturer so you might need to adjust them

# Create some pen colours for drawing with
BLACK = display.create_pen(0, 0, 0)
GREY = display.create_pen(190, 190, 190)
GREEN = display.create_pen(0, 255, 0)
RED = display.create_pen(255, 0, 0)

while True:
    # convert the raw ADC read into a voltage, and then a percentage
    voltage = vsys.read_u16() * conversion_factor
    percentage = 100 * ((voltage - empty_battery) / (full_battery - empty_battery))
    if percentage > 100:
        percentage = 100

    # draw the battery outline
    display.set_pen(BLACK)
    display.clear()
    display.set_pen(GREY)
    display.rectangle(0, 0, 220, 135)
    display.rectangle(220, 40, 20, 55)
    display.set_pen(BLACK)
    display.rectangle(3, 3, 214, 129)

    # draw a green box for the battery level
    display.set_pen(GREEN)
    display.rectangle(5, 5, int((210 / 100) * percentage), 125)

    # add text
    display.set_pen(RED)
    if charging.value() == 1:         # if it's plugged into USB power...
        display.text("Charging!", 15, 90, 240, 4)

    display.text('{:.2f}'.format(voltage) + "v", 15, 10, 240, 5)
    display.text('{:.0f}%'.format(percentage), 15, 50, 240, 5)

    display.update()
    time.sleep(0.5)