Garage Status System

Features

Detect door open/closed
Reporting of door status over time
Temperature reporting for garage interior

Future Work

Occupancy detection via PIR sensor
Door control
Occupancy detection via bluetooth LE (if the garage controller module has the capability, like the ItsyBitsy nRF52840). Could also be a useful door control.

Using a Pico

The Raspberry Pi Pico microcontroller is actually available at a reasonable price at the time of writing. Since the radio modules used for this project are somewhat standalone, the primary microcontroller does not need any radios of its own and we can use a “plain” Pico.

Alpine Doesn’t Work (yet)

Tried this first, ran into issues with GCC. The cross compilation we want to do is only supported in Alpine edge at the time of writing, while current is 3.17. So I guess we’re going with Debian!

SDK Setup

The getting started guide is available here: https://datasheets.raspberrypi.com/pico/getting-started-with-pico.pdf.

A docker file is included in the src directory that will populate a plain Debian linux container with the necessary libraries and toolchain to complete a build.

Once you have a builder container set up, clone it and give it a name. To do this, determine the container’s current ID with docker ps -a, then run docker commit <container hash> <friendly name, like debian-for-pico>.

Copy code for pico into container

Assuming this configuration as a precondition:

% docker ps -a
CONTAINER ID   IMAGE                  COMMAND        NAMES
a750ed171000   debian-for-pico        "/bin/sh"      debian-builder

Attach a shell to the running container with docker exec -it debian-builder /bin/sh.
Copy the contents of the pico source directory into the container with docker cp pico/src/. debian-builder:/home/builder/garage-guardian. Note the trailling dot (.) indicating copy the contents, not the directory.
Within the container cp /home/builder/pico-sdk/external/pico_sdk_import.cmake /home/builder/garage-guardian
1. cd /home/builder/garage-guardian.
2. mkdir build && cd build && cmake -DPICO_SDK_PATH=/home/builder/pico-sdk ...
3. make, watch the fireworks.
Upon successful build, docker cp <container name>:/home/builder/garage-guardian/build/garage_guardian.uf2 <some place on host>

Using Named Volumes

To use volumes, you can do something like this:

docker run --name debian-builder -v garage-guardian/src:/home/builder/garage-guardian -it --detach debian-for-pico /bin/sh

to run it with mounted volumes.

Door Switch Reading

Using GPIO in pullup mode, set as an input, we can read when it’s pulled low by the door switch.

Switch lead 1 -> 1k resistor -> ground
GPIO -> switch lead 2

The GPIO initialization code looks like this:

gpio_init(SENSE_PIN);
gpio_set_dir(SENSE_PIN, GPIO_IN);
gpio_pull_up(SENSE_PIN);

Using and ESP8266

Small, cheap, widely available. Using an ESP8266 solves the issue of bridging between a LAN and the 433 MHz radio pair. The receiving radio will deliver data to a host on the network, or send notifications via email directly to a delivery server.

A good reason to go with an ESP8266 is that it’s supported by the Radiohead library for the radio pair we’re using. The pico on the other hand has incomplete support from Radiohead and would require a custom implementation. While this is doable with enough investigation and time, it will add significantly to the project’s complexity.

WRuman/garage-guardian