Merge pull request #123 from helgibbons/main

Add Pico Lipo SHIM example
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Philip Howard 2021-04-16 15:54:26 +01:00 committed by GitHub
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# This example shows how to read the voltage from a lipo battery connected to a Raspberry Pi Pico via our Pico Lipo SHIM, 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 Explorer.
# Remember to save this code as main.py on your Pico if you want it to run automatically!
from machine import ADC, Pin
import utime
import picodisplay as display # change "picodisplay" to "picoexplorer" if you're using a Pico Explorer
# Set up and initialise display
buf = bytearray(display.get_width() * display.get_height() * 2)
display.init(buf)
display.set_backlight(0.8) # comment out this line if you have a Pico Explorer as it doesn't have a controllable backlight
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 # these are our 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
while True:
voltage = vsys.read_u16() * conversion_factor
percentage = 100 * ((voltage - empty_battery) / (full_battery - empty_battery))
if percentage > 100:
percentage = 100.00
# draws the battery
display.set_pen(0, 0, 0)
display.clear()
display.set_pen(190, 190, 190)
display.rectangle(0, 0, 220, 135)
display.rectangle(220, 40, 20, 55)
display.set_pen(0, 0, 0)
display.rectangle(3, 3, 214, 129)
display.set_pen(0, 255, 0)
display.rectangle(5, 5, round(210 / 100 * percentage), 125)
# adding text
display.set_pen(255, 0, 0)
if charging.value() == 1: # if it's plugged into USB power...
display.text("Charging!", 15, 55, 240, 4)
else: # if not, display the battery stats
display.text('{:.2f}'.format(voltage) + "v", 15, 10, 240, 5)
display.text('{:.0f}%'.format(percentage), 15, 50, 240, 5)
display.update()
utime.sleep(1)