FunHouse Mail Slot Detector

by John Park

published May 11, 2021, last edited January 14, 2025

posted in Sensors/ Light Internet of Things - IOT/ Adafruit IO Internet of Things - IOT/ Wireless CircuitPython

Beginner

Project guide

Overview

Waiting for that very special piece of mail? This mail slot detector will alert you when the mail arrives in your mail slot. Using a break beam sensor, FunHouse running CircuitPython, and Adafruit IO, you'll get an alert when the mail has been delivered.

Parts

Top-down video of Adafruit Funhouse PCB. The TFT display shows a data readout, and the NeoPixel LEDs glow rainbow colors.

Adafruit FunHouse - WiFi Home Automation Development Board

Home is where the heart is...it's also where we keep all our electronic bits. So why not wire it up with sensors and actuators to turn our house into an electronic wonderland....

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IR Break Beam Sensor with ruler blocking between receiver and transmitter

IR Break Beam Sensors with Premium Wire Header Ends - 3mm LEDs

Infrared (IR) break-beam sensors are a simple way to detect motion. They work by having an emitter side that sends out a beam of human-invisible IR light, then a receiver across the...

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2 x STEMMA JST PH 3-Pin to Female Socket Cable

200mm

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USB Type A to Type C Cable - approx 1 meter / 3 ft long

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5V 2A Switching Power Supply with USB-A Connector

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Clear Adhesive Squares - 6 pack

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Opened box full of short lengths of multi color heat shrink

Pre-Cut Multi-Colored Heat Shrink Pack Kit - 280 pcs

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Adafruit IO Setup

New to Adafruit IO? You can read all about it in this guide. Go ahead and get your account set up, and come back to this page when you're ready.

You'll need to obtain our Adafruit IO Key and Username. Visit your Adafruit IO Profile page and click the VIEW AIO KEY button on the left-sidebar.

A window will pop up with your Adafruit IO key and username. Keep a copy of them in a safe place, you'll need them later.

Setting up Adafruit IO Feeds

You'll create a feed called mail to receive the door switch status data sent by the Funhouse.

To create the feed for the door, navigate to the Adafruit IO Feeds Page and click Actions->Create a New Feed. Name the new feed door and then click Create.

If you do not know how to create feeds, head over to the Adafruit IO Basics: Feeds for a quick overview of this process.

Creating the Adafruit IO Dashboard

Next, you'll create an Adafruit IO Dashboard to display and control the feeds. Navigate to the Adafruit IO Dashboard page and click Actions -> Create a New Dashboard.

Name this dashboard Funhouse Mail Alert and click Create. You'll be redirected to the new Dashboard.

Add a Block

You'll create an Indicator Block to monitor the status of the door sensor.

From the IO Home dashboard, click the gear icon to see the Dashboard Settings and then click on Create New Block to add a new block to the dashboard.

Click the Indicator block. This will take you to the Connect a Feed window.

Pick Block Feed

Select the mail feed and then click Next step.

Configure Block

Configure its settings like so:

Set the Block Title to Mail Slot Status
On Color is blue
Off Color is amber
Conditions is set to = 0

This means the block will be on (blue) when the Funhouse sends a 0 to the mail feed and off (amber) when the Funhouse sends a 1 to the mail feed.

When you're done, click Create block.

Email and Text Alerts

To set up Email and Text alerts for your feed, check out this page!

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Code the FunHouse Mail Detector

Install CircuitPython

The first think to do is install CircuitPython on your Funhouse. Follow this guide to get it set up with the latest release version.

Text Editor

Adafruit recommends using the Mu editor for using your CircuitPython code with the Funhouse. You can get more info in this guide.

Shhhh... Secrets

In order for the Funhouse to connect to the internet, you'll need to include a secrets.py file on the board that contains your WiFi access point ssid and password, as well as your AIO key.

Follow this guide page to get your secrets.py file set up.

Download the Project Bundle

Your project will use a specific set of CircuitPython libraries and the code.py file. In order to get the libraries you need, click on the Download Project Bundle link below, and uncompress the .zip file.

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# SPDX-FileCopyrightText: Copyright (c) 2021 John Park for Adafruit
#
# SPDX-License-Identifier: MIT
# FunHouse Mail Slot Detector

import board
from adafruit_debouncer import Debouncer
from displayio import CIRCUITPYTHON_TERMINAL
from digitalio import DigitalInOut, Pull
from adafruit_funhouse import FunHouse


beam_sense_pin = DigitalInOut(board.A0)  # defaults to input
beam_sense_pin.pull = Pull.UP  # turn on internal pull-up resistor
beam_sensor = Debouncer(beam_sense_pin)

AMBER = 0xF0D000
BLUE = 0x00D0F0
RED = 0xFF0000
WHITE = 0xFFFFFF
GRAY = 0x606060

funhouse = FunHouse(default_bg=None, scale=3)
funhouse.peripherals.dotstars.brightness = 0.05
funhouse.peripherals.dotstars.fill(AMBER)

# Create the labels
funhouse.display.root_group = CIRCUITPYTHON_TERMINAL
mail_label = funhouse.add_text(
    text="No Mail yet", text_position=(4, 14), text_color=AMBER
)
reset_label = funhouse.add_text(text="reset", text_position=(3, 70), text_color=GRAY)

funhouse.display.root_group = funhouse.splash


def send_io_data(mail_value):
    funhouse.peripherals.led = True
    funhouse.network.push_to_io("mail", mail_value)
    funhouse.peripherals.led = False


send_io_data(1)

while True:
    beam_sensor.update()

    if beam_sensor.fell:
        funhouse.peripherals.set_dotstars(RED, WHITE, BLUE, WHITE, RED)
        funhouse.peripherals.play_tone(2000, 0.25)
        funhouse.set_text("Mail is here!", mail_label)
        funhouse.set_text_color(BLUE, mail_label)
        send_io_data(0)

    if funhouse.peripherals.button_down:
        funhouse.peripherals.dotstars.fill(AMBER)
        funhouse.set_text("No Mail yet", mail_label)
        funhouse.set_text_color(AMBER, mail_label)
        send_io_data(1)

# SPDX-FileCopyrightText: Copyright (c) 2021 John Park for Adafruit
#
# SPDX-License-Identifier: MIT
# FunHouse Mail Slot Detector

import board
from adafruit_debouncer import Debouncer
from displayio import CIRCUITPYTHON_TERMINAL
from digitalio import DigitalInOut, Pull
from adafruit_funhouse import FunHouse


beam_sense_pin = DigitalInOut(board.A0)  # defaults to input
beam_sense_pin.pull = Pull.UP  # turn on internal pull-up resistor
beam_sensor = Debouncer(beam_sense_pin)

AMBER = 0xF0D000
BLUE = 0x00D0F0
RED = 0xFF0000
WHITE = 0xFFFFFF
GRAY = 0x606060

funhouse = FunHouse(default_bg=None, scale=3)
funhouse.peripherals.dotstars.brightness = 0.05
funhouse.peripherals.dotstars.fill(AMBER)

# Create the labels
funhouse.display.root_group = CIRCUITPYTHON_TERMINAL
mail_label = funhouse.add_text(
    text="No Mail yet", text_position=(4, 14), text_color=AMBER
)
reset_label = funhouse.add_text(text="reset", text_position=(3, 70), text_color=GRAY)

funhouse.display.root_group = funhouse.splash


def send_io_data(mail_value):
    funhouse.peripherals.led = True
    funhouse.network.push_to_io("mail", mail_value)
    funhouse.peripherals.led = False


send_io_data(1)

while True:
    beam_sensor.update()

    if beam_sensor.fell:
        funhouse.peripherals.set_dotstars(RED, WHITE, BLUE, WHITE, RED)
        funhouse.peripherals.play_tone(2000, 0.25)
        funhouse.set_text("Mail is here!", mail_label)
        funhouse.set_text_color(BLUE, mail_label)
        send_io_data(0)

    if funhouse.peripherals.button_down:
        funhouse.peripherals.dotstars.fill(AMBER)
        funhouse.set_text("No Mail yet", mail_label)
        funhouse.set_text_color(AMBER, mail_label)
        send_io_data(1)

Next, drag the contents of the uncompressed bundle directory onto you microcontroller board CIRCUITPY drive, replacing any existing files or directories with the same names, and adding any new ones that are necessary.

How it Works

The Funhouse Mail Detector acts a bit like a simple switch that sends data to Adafruit IO when it detects a change. To do this, you first import some libraries.

Libraries

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import board
from adafruit_debouncer import Debouncer
from digitalio import DigitalInOut, Pull
from adafruit_funhouse import FunHouse

import board
from adafruit_debouncer import Debouncer
from digitalio import DigitalInOut, Pull
from adafruit_funhouse import FunHouse

The board library provides pin definitions. digitalio is used to check the switch.

adafruit_debouncer make it easy to check for switch open and switch close events.

adafruit_funhouse allows simple access to the Dotstar LEDs, via the peripherals layer, as well as the network layer used to connect to the internet and send messages to Adafruit IO

Setup

Next you'll do some setup including setting up the break beam sensor on the A0 pin, creating the debouncer object on that pin, setting LED color variables, and creating the funhouse object.

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beam_sense_pin = DigitalInOut(board.A0)  # defaults to input
beam_sense_pin.pull = Pull.UP  # turn on internal pull-up resistor
beam_sensor = Debouncer(beam_sense_pin)
 
AMBER = 0xF0D000
BLUE = 0x00D0F0
RED = 0xFF0000
WHITE = 0xFFFFFF
GRAY = 0x606060
 
funhouse = FunHouse(default_bg=None, scale=3)
funhouse.peripherals.dotstars.brightness = 0.05
funhouse.peripherals.dotstars.fill(AMBER)

beam_sense_pin = DigitalInOut(board.A0)  # defaults to input
beam_sense_pin.pull = Pull.UP  # turn on internal pull-up resistor
beam_sensor = Debouncer(beam_sense_pin)
 
AMBER = 0xF0D000
BLUE = 0x00D0F0
RED = 0xFF0000
WHITE = 0xFFFFFF
GRAY = 0x606060
 
funhouse = FunHouse(default_bg=None, scale=3)
funhouse.peripherals.dotstars.brightness = 0.05
funhouse.peripherals.dotstars.fill(AMBER)

FunHouse Display

You'll set up the FunHouse display with text labels to show the state of the mail slot, and to label the reset button.

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# Create the labels
funhouse.display.root_group = CIRCUITPYTHON_TERMINAL
mail_label = funhouse.add_text(
    text="No Mail yet", text_position=(4, 14), text_color=AMBER
)
reset_label = funhouse.add_text(text="reset", text_position=(3, 70), text_color=GRAY)
 
funhouse.display.root_group = funhouse.splash

# Create the labels
funhouse.display.root_group = CIRCUITPYTHON_TERMINAL
mail_label = funhouse.add_text(
    text="No Mail yet", text_position=(4, 14), text_color=AMBER
)
reset_label = funhouse.add_text(text="reset", text_position=(3, 70), text_color=GRAY)
 
funhouse.display.root_group = funhouse.splash

Send IO Data Function

You'll create a function to send either a 0 or a 1 to the AIO door feed when the beam is broken or reset.

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def send_io_data(mail_value):
    funhouse.peripherals.led = True
    funhouse.network.push_to_io("mail", mail_value)
    funhouse.peripherals.led = False

def send_io_data(mail_value):
    funhouse.peripherals.led = True
    funhouse.network.push_to_io("mail", mail_value)
    funhouse.peripherals.led = False

Main Loop

The main loop of the program checks the switch pin with the debouncer's beam_sensor.update() function.

Two if statement do the rest. If the beam sensor state falls, the mail has arrived and the feed is sent a message with the data value 0.

If the reset button is pressed, the feed is sent a message with the data value 1.

This configuration of triggering only on a state change is helpful, because it means the board won't be constantly spamming the AIO feed with data!

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Build the Mail Detector

Break Beam

The mail slot detector uses a type of sensor called a break beam sensor. It is made of two parts, an emitter and a sensor. When the sensor has a clear line of sign to the emitter, everything is fine, when the beam is broken, it'll trigger the code to send an alert.

The emitter is an infrared (IR) LED that is always on. It has a black wire and a red wire that connect to ground and power, respectively.

The sensor has three wires for ground, power, and signal.

Connect to FunHouse

To connect the break beam sensor to the FunHouse you'll use a couple of JST-PH cables.

You can plug them in directly as shown above, simply match the colors of each wire.

For a more secure fit, a piece of heat shrink tubing is helpful. Add a bit to each bundle for wire management, and a larger piece to secure the connections.

Note one white wire will remain unused.