4. Duty Cycle Challenge

Objective

We’re going to now use the last circuit to learn about duty cycle simply by tuning our code.

Wiring

Follow the circuit diagram provided to wire the Metro M0 Express. (Same circuit as "Blinking LED and Button").

Coding/Programming

import time

import board

import pulseio

from digitalio import DigitalInOut, Direction, Pull

import simpleio

led = pulseio.PWMOut(board.D13, frequency=5000, duty_cycle=0)

button = DigitalInOut(__________)

button.direction = Direction.__________

button.pull = Pull.UP

buttonState = False

ledState = False

count = -1

dutycycle = 0

button_out = [0, 13101, 26209, 39318, 52426, 65535, 0]

while True:

buttonState = button.value

if buttonState:

count = count + 1

led.duty_cycle = button_out[count]

print(led.duty_cycle)

dutycycle = round(simpleio.map_range(button_out[count], 0, 65535, 0, 100))

print("Duty Cycle:", dutycycle, "%")

time.sleep(0.3)

if count == 6:

count = 0

Note: analog output range is 0 to 65535 (16 bit)
Note 2: Some students have reported issues using pulseio, so if that doesn't work, try changing all instances of pulseio to pwmio.