Software Sensor

• For hardware design see: https://github.com/larus-breeze/hw_sensor

Facts

• STM32CubeIDE
• STM32F407VG
• FreeRTOS
• IMU
• GNSS
• Static pressure
• Differential pressure
• CAN interface
• Bluetooth ESP32
• RS232 NMEA output channels

How to use it

Some usefull git commands to work with this repository and the included submodule command line:

Clone via https:

git clone --recurse-submodules https://github.com/larus-breeze/sw_sensor

Clone via ssh:

git clone --recurse-submodules git@github.com:larus-breeze/sw_sensor.git

Switch to a branch:

git checkout branch_name --recurse-submodules

Pull latest changes:

git pull --recurse-submodules  

STM32 Build Configurations

• Release used for release versions (Max. optimized, no debug info)
• Debug used for development

Building firmware from the command line

Python dependencies (from the repository root):

python3 -m venv .venv
source .venv/bin/activate   # Windows: .venv\Scripts\activate
pip install -r requirements.txt

build_firmware_all.py builds both the STM32 (via STM32CubeIDE's headless build mode) and ESP32 (via arduino-cli) firmware:

python3 build_firmware_all.py

This leaves 5 files in the gitignored build/ directory, all tagged with the same <version> (from git describe):

• larus_sensor_stm32_v<version>.bin — STM32 update image for the SD card or the ESP32 web UI's "STM32 firmware update" section.
• larus_sensor_stm32_v<version>.elf — plain STM32 ELF, for flashing directly with STM32CubeProgrammer (see "Flash and prepare the sensor hardware" below).
• larus_sensor_esp32_v<version>.bin — ESP32 application image, for the web UI's own "ESP32 WiFi module update" section.
• larus_sensor_esp32_v<version>.flash1_boot.bin / ...flash2_app.bin — ESP32 images for a from-scratch USB flash via esptool-js (see sw_esp32/README.md), not used from the web UI.

The two files needed to update a sensor from its own web UI are the first and third: larus_sensor_stm32_v<version>.bin and larus_sensor_esp32_v<version>.bin.

Pass --skip-stm32/--skip-esp32 to build only one side, or see sw_stm32/scripts/README.md/sw_esp32/README.md to run either side's scripts/build_firmware.py directly with more options (e.g. pointing at a non-standard STM32CubeIDE install location).

Flash and prepare the sensor hardware

STM32

• Flash via USB using the STM32CubeProgrammer and a compiled binary sw_sensor.elf file from here: https://github.com/larus-breeze/sw_sensor/releases
  Hold the Boot Button on power-on to start the STM32 in the DFU bootloader mode. Use the STM32CubeProgrammer to flash the binary to the STM32 micro-controller.

ESP32 controller

• The sketch lives in sw_esp32/wlan_link/ (not ESP32_Firmware/) and hosts a WiFi access point with a web UI for STM32/ESP32 firmware updates and *.lrsx log file management. WiFi AP SSID/password are generated automatically per device, not set manually.
• See sw_esp32/README.md for build/flash instructions, including an initial flash straight from the browser via esptool-js, no local toolchain needed.

Prepare an sd-card with configuration files

• put a larus_sensor_config.ini file (template in configuration/) in the sd cards root directory. Adjust the parameters as described in configuration/README.md Initially the heading may be inaccurate as the magnetic calibration algorithm needs some time in the air to find the exact calibration. A 30 minutes flight with some right and left turns should be sufficient to calibrate the compass module.
• Optionally: Create a directory with the name "logger" to enable logging of all measurement data with 100Hz via .lrsx files.
• Optionally: Create a directory with the name "eeprom" to enable the creation of cleartext eeprom dumps including the installed firmware version and hardware id.

Additional developer options

• Put an empty file with the name: "sensor.readings" in order to switch the serial output format from Larus NMEA syntax to pure sensor raw data values.

Led signal indications

There are LEDs on the PCBs edge which indicate the following

• SD-CARD (blue)
  • Off: No uSD-Card detected
  • On: uSD-Card detected
  • Flashing: Actively logging (writing) to card
• SYSTEM (blue)
  • Off: System not working at all
  • Flashing: Indicates that FreeRTOS and the tasks are running.
• GNSS (blue)
  • Off: No GNSS fix
  • Flashing: GNSS fix
• ERROR (red)
  • Flashing: at least one of the sensors IMU, static pressure, dynamic pressure or GNSS is not working.
  • Sporadic flashing: DGNSS heading fix is briefly missing.
• ESP (blue)
  • Not used currently