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Door State Monitor

LoRa
MicroPython Firmware
Wiring Required

Receive notifications when a door is opened or closed.

You Will Need

Blues Starter Kit for LoRaWAN
Raspberry Pi Pico
2 USB A to micro USB cables
Magnetic Door Switch Set

Before you can use the Notecard LoRa you need to have a LoRaWAN gateway that is provisioned to The Things Network. To make this easy you can use the Blues Indoor LoRaWAN Gateway. To get this set up follow the setup instructions

Pico Setup

Your Raspbery Pi Pico will need to have Micropython installed. If it is not yet installed, follow the installation instructions provided by MicroPython.

MicroPython Code

The script that will run on the MCU is main.py. It depends on note-python, a Python library for communicating with a Notecard.

note-python

To get the note-python files onto the MCU, use the setup_board.py script. This uses the pyboard.py script to communicate with the Raspberry Pi Pico. First, you must identify the MCU's serial port. On Linux, it'll typically be something like /dev/ttyACM0. You can run ls /dev/ttyACM* before and after plugging the board in to figure out the serial port's associated file. Once you have that, run python setup_board.py <serial port>, replacing <serial port> with your serial port. This script does a few things:

Clones note-python from GitHub.
Creates the /lib and /lib/notecard directories on the MCU.
Copies the .py files from note-python/notecard on your development machine to /lib/notecard on the MCU.
Lists the contents of /lib/notecard so you can verify that everything was copied over.

Note that for pyboard.py to work, you'll need to install pyserial with pip install pyserial, if you don't have it installed already.

Running `main.py`

Before running main.py, uncomment this line: # product_uid = 'com.your-company:your-product-name'. Replace com.my-company.my-name:my-project with the ProductUID of the Notehub project you created in Notehub Setup.

Copy main.py over to the board with this command:

Code

python pyboard.py -d <serial port> --no-soft-reset -f cp main.py :/

Make sure to replace <serial port> with your serial port. main.py will start running after boot up.

Hardware

The magnetic door switch consists of two plastic terminals, one of which has a pair of wires coming out of it. When the terminals are brought into contact (or close proximity), an internal reed switch is closed and the two wires are electrically connected. As shown on the SparkFun product site, the terminal with the wires is typically mounted to a door frame and the other terminal is mounted to the door such that when the door is closed, the two terminals are adjacent, closing the switch. Since we're just testing things out, don't mount the terminals yet.

Place the Pico into a Breadboard with the USB connection on the outer edge. Make the following connections:

Pico Power:

GND on Pico (Pin 38) to Breadboard Ground Rail
3V3 OUT on Pico (Pin 36) to Breadboad +VE Rail

Door Sensor:

GP26 on Pico (Pin 31) to Magnetic Door Sensor
GND Rail on Breadboard to Magnetic Door Sensor

The Notecarrier can be connected with a Qwiic cable with the following connections:.

Qwiic Black (GND) to Pico GND (Pin 3)
Qwiic Blue (SDA) to Pico GP4 (Pin 6)
Qwiic Yellow (SCL) to Pico GP5 (Pin 7)

Do not connect the Red cable of the Qwiic connector. If you wish to power the Pico from the Notecarrier (which makes sense after testing) connect VMAIN on the Notecarrier to VSYS (Pin 39) on the Pico.

See the image below for a diagram of the connections required.

Diagram of Breadboard Circuit

Once complete the build should look a little like this:

Complete Breadboard Build

Testing

Bring the terminals together. You should see the message Door closed. in the serial log. Then, on the events page of your Notehub project, you should see a Note that reads {"closed":true}, indicating the door is closed.
Separate the terminals. You should see the message Door open. in the serial log. Then, on the events page of your Notehub project, you should see a Note that reads {"open":true}, indicating the door is open.