Add CircuitPython Code

In the embedded code element below, click on the Download: Project Zip link, and save the .zip archive file to your computer.

Then, uncompress the .zip file, it will unpack to a folder named Adafruit_IO_Power_Relay.

Copy the contents of Adafruit_IO_Power_Relay directory to your PyPortal's CIRCUITPY drive.

# SPDX-FileCopyrightText: 2020 Brent Rubell for Adafruit Industries
# SPDX-License-Identifier: MIT

import time
import board
import busio
from digitalio import DigitalInOut
import neopixel
import adafruit_connection_manager
from adafruit_esp32spi import adafruit_esp32spi
from adafruit_esp32spi import adafruit_esp32spi_wifimanager

import adafruit_minimqtt.adafruit_minimqtt as MQTT

### WiFi ###

# Get wifi details and more from a file
    from secrets import secrets
except ImportError:
    print("WiFi secrets are kept in, please add them there!")

# If you are using a board with pre-defined ESP32 Pins:
esp32_cs = DigitalInOut(board.ESP_CS)
esp32_ready = DigitalInOut(board.ESP_BUSY)
esp32_reset = DigitalInOut(board.ESP_RESET)

# If you have an externally connected ESP32:
# esp32_cs = DigitalInOut(board.D9)
# esp32_ready = DigitalInOut(board.D10)
# esp32_reset = DigitalInOut(board.D5)

spi = busio.SPI(board.SCK, board.MOSI, board.MISO)
esp = adafruit_esp32spi.ESP_SPIcontrol(spi, esp32_cs, esp32_ready, esp32_reset)
"""Use below for Most Boards"""
status_light = neopixel.NeoPixel(
    board.NEOPIXEL, 1, brightness=0.2
)  # Uncomment for Most Boards
"""Uncomment below for ItsyBitsy M4"""
# status_light = dotstar.DotStar(board.APA102_SCK, board.APA102_MOSI, 1, brightness=0.2)
# Uncomment below for an externally defined RGB LED
# import adafruit_rgbled
# from adafruit_esp32spi import PWMOut
# RED_LED = PWMOut.PWMOut(esp, 26)
# GREEN_LED = PWMOut.PWMOut(esp, 27)
# BLUE_LED = PWMOut.PWMOut(esp, 25)
# status_light = adafruit_rgbled.RGBLED(RED_LED, BLUE_LED, GREEN_LED)
wifi = adafruit_esp32spi_wifimanager.ESPSPI_WiFiManager(esp, secrets, status_light)

# Set up a pin for controlling the relay
power_pin = DigitalInOut(board.D3)

### Feeds ###
# Set up a feed named Relay for subscribing to the relay feed on Adafruit IO
feed_relay = secrets["aio_username"] + "/feeds/relay"

### Code ###

# Define callback methods which are called when events occur
# pylint: disable=unused-argument, redefined-outer-name
def connected(client, userdata, flags, rc):
    # This function will be called when the client is connected
    # successfully to the broker.
    print("Connected to Adafruit IO!")

def disconnected(client, userdata, rc):
    # This method is called when the client is disconnected
    print("Disconnected from Adafruit IO!")

def subscribe(client, userdata, topic, granted_qos):
    # This method is called when the client subscribes to a new feed.
    print("Subscribed to {0}".format(topic))

def unsubscribe(client, userdata, topic, pid):
    # This method is called when the client unsubscribes from a feed.
    print("Unsubscribed from {0} with PID {1}".format(topic, pid))

def on_message(client, topic, message):
    # Method callled when a client's subscribed feed has a new value.
    print("New message on topic {0}: {1}".format(topic, message))

def on_relay_msg(client, topic, value):
    # Called when relay feed obtains a new value
    print("Turning Relay %s"%value)
    if value == "ON":
        power_pin.value = True
    elif value == "OFF":
        power_pin.value = False
        print("Unexpected value received on relay feed.")

# Connect to WiFi
print("Connecting to WiFi...")

pool = adafruit_connection_manager.get_radio_socketpool(esp)
ssl_context = adafruit_connection_manager.get_radio_ssl_context(esp)

# Set up a MiniMQTT Client
client = MQTT.MQTT(

# Setup the callback methods above
client.on_connect = connected
client.on_disconnect = disconnected
client.on_subscribe = subscribe
client.on_unsubscribe = unsubscribe
client.on_message = on_message
# Add a callback to the relay feed
client.add_topic_callback(feed_relay, on_relay_msg)

# Connect the client to Adafruit IO
print("Connecting to Adafruit IO...")

# Subscribe to all updates on relay feed

while True:
    try: # Poll for new messages on feed_relay
    except (ValueError, RuntimeError, ConnectionError, OSError) as e:
        print("Failed to get data, retrying\n", e)

Once all the files are copied from your computer to the PyPortal, you should have the following files on your CIRCUITPY drive:

Secrets File Setup

Open the file on your CircuitPython device using Mu or your favorite text editor. You're going to edit this file to enter your WiFi credentials along with your keys. 

  • Change ssid to the name of your WiFi network
  • Change password to your WiFi network's password 
  • Change aio_username to your Adafruit IO Username
  • Change aio_key to your Adafruit IO Key.
secrets = {
    'ssid' : 'home ssid',
    'password' : 'my password',
    'timezone' : "America/New_York", #
    'aio_username' : 'MY_ADAFRUIT_IO_USERNAME',
    'aio_key' : 'MY_ADAFRUIT_IO_KEY',

Test Code

Before wiring everything up, it's important to test the code so it works as-expected.

Open the CircuitPython REPL. The following should output in the REPL: output:
Connecting to WiFi...
Connecting to Adafruit IO...
Connected to Adafruit IO!
Subscribed to brubell/feeds/relay

Navigate to the Adafruit IO Dashboard you created earlier and toggle the Power switch.

The REPL should output "Turning Relay ON"

Toggling the power switch to the off position should output "Turning Relay OFF" in the REPL.

This guide was first published on Sep 22, 2020. It was last updated on Mar 01, 2024.

This page (Code PyPortal with CircuitPython) was last updated on Mar 01, 2024.

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