CircuitPython/Adafruit Feather M0 Express

Adafruit Feather M0 Express CircuitPython Examples

Here are a few of my example code for the Adafruit Feather M0 Express.

You may find a more information about the board on the website.

The current CircuitPython firmware for the Feather M0 Express can be found at circuitpython.org.

Read the battery voltage

<syntaxhighlight lang=python>

1. Read Battery Voltage - Adafruit Feather M0 Express

import board import analogio import time

vbat_voltage = analogio.AnalogIn(board.D9)

1. Define the get_voltage function

def get_voltage(pin):

   return (pin.value * 3.3) / 65536 * 2

1. Run the Main loop

while True:

   # Get the current voltage
   battery_voltage = get_voltage(vbat_voltage)
   
   # Just for demo purposes, print the current voltage
   print("VBat voltage: {:.2f}".format(battery_voltage))
   time.sleep(5)

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Analog Out

This example shows you how you can set the DAC (true analog output) on pin A0.

<syntaxhighlight lang=python>

1. CircuitPython IO demo - analog output

import board from analogio import AnalogOut

analog_out = AnalogOut(board.A0)

while True:

   # Count up from 0 to 65535, with 64 increment
   # which ends up corresponding to the DAC's 10-bit range
   for i in range(0, 65535, 64):
       analog_out.value = i

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PWM with Fixed Frequency

Your board has pulseio support, which means you can PWM LEDs, control servos, beep piezos, and manage "pulse train" type devices like DHT22 and Infrared.

Nearly every pin has PWM support! For example, all ATSAMD21 board have an A0 pin which is 'true' analog out and does not have PWM support.

<syntaxhighlight lang=python> import time import board import pulseio

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

while True:

   for i in range(100):
       # PWM LED up and down
       if i < 50:
           led.duty_cycle = int(i * 2 * 65535 / 100)  # Up
       else:
           led.duty_cycle = 65535 - int((i - 50) * 2 * 65535 / 100)  # Down
       time.sleep(0.01)

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