Ble door sensor

Bluetooth Window/Door Sensor

A simple project to observe a window or door is open/closed. It works like most other sensors as well. A magnet has to get attached to the door and if it comes near the board, it is detected and the state of the window or door is updated.

How to build

If you are new to Zephyr, read the Getting Started Guide. Afterwards you can clone and build this project with:

west init -m https://github.com/gumulka/ble_door_sensor --mr main door_sensor
cd door_sensor
west update
cd ble_door_sensor

Bootloader

The bootloader will load and verify the image that is executed. To make it easier to upgrade the device, two images are saved on the device and only one is being executed, while the other is a standby for updating. The bootloader cannot be upgraded via ble, but the image can be. Therefore making it possible to upgrade devices in the field.

If you have a unprogrammed device, use this to build and flash the bootloader:

west build -p -b ble_door_sensor -d build_mcuboot ../bootloader/mcuboot/boot/zephyr/ -- -DCONFIG_BOOT_SIGNATURE_TYPE_ECDSA_P256=y
west flash -d build_mcuboot

Application

The application is different from the bootloader and is what is in need of updates/upgrades.

west build -p -b ble_door_sensor app
west flash

It is also possible to build the application with debug output for the UART on the backside of the board. This is disabled by default as it has a significant influence on battery.

west build -p -b ble_door_sensor app -- -DEXTRA_CONF_FILE=="debug.conf"

Energy sensor

When I wanted to integrate energy consumption into home assistant without having to order new hardware, I soldered two resistors to the board and converted it into an energy monitor. A 1M Ohm between VCC and AIN0 and 22k Ohm between AIN0 and GND. This can be configured with:

west build -p -b ble_door_sensor app -- -DEXTRA_DTC_OVERLAY_FILE=="energy-tracker.dtsi"

Update via BLE

If you have an already running device and just want to upgrade to the latest firmware.

Either with the nRF Connect App, which can be quite handy, or in the commandline use these steps:

sudo mcumgr --conntype ble --connstring ctlr_name=hci0,peer_name='Sensor' image upload build/zephyr/zephyr.signed.bin
sudo mcumgr --conntype ble --connstring ctlr_name=hci0,peer_name='Sensor' image list

Use the second hash provided from the second command to alter the following:

sudo mcumgr --conntype ble --connstring ctlr_name=hci0,peer_name='Sensor' image test "HASH_FROM_OUTPUT"
sudo mcumgr --conntype ble --connstring ctlr_name=hci0,peer_name='Sensor' reset
# wait for the system to restart and if you are sure, that the update was successful then
sudo mcumgr  --conntype ble --connstring ctlr_name=hci0,peer_name='Sensor' image confirm "HASH_FROM_OUTPUT"

More information about the general procedure can be found here and here

[!TIP] I have seen a few errors when trying to upload the image and found that it works best, if I cancel the upload command after a few seconds and restart it a few seconds later, basically splitting the upload into 4-5 chunks instead of uploading it as a whole.