Capacitor Charging with micro:bit (MakeCode Python)
This project illustrates how a capacitor can be charged at different rates using a potentiometer (variable resistor) and displays the current voltage using the micro:bit LEDs and a set of four coloured LEDs.
It is based on a project from the Kitronic Inventor’s Kit for micro:bit. See here for more and links to a circuit diagram: https://kitronik.co.uk/blogs/resources/inventors-kit-experiment-9-help
The Python code is for use in MakeCode: https://makecode.microbit.org/_LYa9MF0Tpcdz
Capacitor Charging using micro:bit and Python in MakeCode
# Manage Capacitor Voltage using micro:bit
# Copyright R J Zealley 06/05/2022
# Licence: copy and resuse with attribution
# Based on Kitronic Inventor's Kit project 10
# https://kitronik.co.uk/products/inventors-kit-for-the-bbc-micro-bit
# Actual capacitor voltage as read from pin 0
cap_voltage = 0
# Percentage of max voltage (3V)
percentage = 0
# Show percentage voltage using 25 microbit LEDs
def show_voltage(v):
# Convert percentage to a fraction for 25 (LEDs)
leds = int(v / 4)
# Check whether each LED should be lit and plot if within range
for x in range(0, 5):
for y in range(0, 5):
check = (x * 5) + y + 1
if check <= leds:
led.plot(x, y)
else:
led.unplot(x, y)
return
# Light four LEDs based on percentage voltage
def light_leds(v):
# tun all LEDs off
pins.digital_write_pin(DigitalPin.P1, 0)
pins.digital_write_pin(DigitalPin.P2, 0)
pins.digital_write_pin(DigitalPin.P8, 0)
pins.digital_write_pin(DigitalPin.P12, 0)
if v > 25:
# Light first LED
pins.digital_write_pin(DigitalPin.P1, 1)
if v > 50:
# Light second LED
pins.digital_write_pin(DigitalPin.P2, 1)
if v > 75:
# Light third LED
pins.digital_write_pin(DigitalPin.P8, 1)
if v > 90:
# Light fourth LED
pins.digital_write_pin(DigitalPin.P12, 1)
return
def on_forever():
global cap_voltage, percentage
# read capacitor voltage from pin 0
cap_voltage = pins.analog_read_pin(AnalogPin.P0)
# Convert value (max 1023) into an (approx) percentage
percentage = cap_voltage / 10
# Display voltage using microbit LEDs
show_voltage(percentage)
# Display voltage on circuit LEDs
light_leds(percentage)
basic. forever(on_forever)
