Is someone sneaking into your lab or workshop? Are family members raiding your secret chocolate drawer? Are your colleagues taking all your shiny new Adafruit components without asking first?

Using Adafruit IO, you can get notified by Email or SMS (paid Adafruit IO plans only) when a door or drawer opens.

In this guide, you will create a door detector project by uploading Adafruit's open-source Wippersnapper firmware to a Raspberry Pi Pico WH, connecting it to Adafruit IO, and using the Adafruit IO web interface to add a door sensor component to your board. Next, you'll create a new Action on Adafruit IO to email you when the door opens. Finally, you'll customize and configure the Action to send a message to your inbox.

This project can be built without programming or soldering!

Required Parts:

The microcontroller board chosen for this project is the Raspberry Pi Pico WH, a powerful little beast with 2MB of flash and the RP2040 as the main processor. In addition, it comes with 2.4GHz Wireless networking support (the W in the model name), and pre-soldered pin headers (the H in WH).

Wippersnapper supports a wide variety of microcontroller boards, so feel free to try an alternative combination.

To complete the no-soldering promise, it's recommended to use a screw-terminal companion board for the pico:

Or if you prefer your own headers and the Terminal PiCowbell to require soldering, then pickup this one instead:

Next, the main star of the show is the humble Reed Switch, or Magnetic contact switch as it's commonly known.

A pre-wired magnetically activated switch in one piece, and a matching magnet in the other piece, this gives a really easy way to detect two surfaces meeting. It can be used for so many things, from the obvious door or window being open, to the more secretive hidden cupboard or interactive puzzle in an escape room; the limit is your imagination.

If they are out of stock then try a local retailer/distributer, DigiKey, or last resort grab some from Amazon (MC-38):

To power the system use a good quality USB Micro-B ended data cable. This is required for installing the firmware, be careful not to use a charge-only cable, but one can be used later during final physical deployment.

Alternatively the VSYS pin can accept 1.8volts to 5.5volts, which is internally used by the Switched-Mode Power Supply (SMPS) to generate the 3.3V for the RP2040 and its GPIO. To easily locate the VSYS pin look at the pin silkscreen labels on back of the Terminal PiCowbell (or check the pinout photos in the product learn guide).

For now, it's best to power the device with a mains-powered USB adapter to avoid worrying about battery recharging, but you could explore using a 3xAA battery case with switch and JST-PH 2 pin connector.