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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.
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# 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
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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
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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 ) )
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if percentage > 100 :
percentage = 100.00
# draws the battery
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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 )
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# 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
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display . text ( ' {:.2f} ' . format ( voltage ) + " v " , 15 , 10 , 240 , 5 )
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display . text ( ' {:.0f} % ' . format ( percentage ) , 15 , 50 , 240 , 5 )
display . update ( )
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utime . sleep ( 1 )