arduino-steami-lib

Arduino/C++ driver library for the STeaMi board. Each driver lives under lib/<component>/ and follows a standard structure.

Repository contents

• Ready-to-use Arduino-compatible drivers
• Consistent API design across all components
• CI integration with clang-format and PlatformIO

Board components

Component	Driver	I2C Address	Description
BQ27441-G1	bq27441	0x55	Battery fuel gauge
DAPLink Flash	daplink_flash	0x3B	I2C-to-SPI flash bridge + config zone
SSD1327	ssd1327	— (SPI)	128x128 greyscale OLED display
MCP23009E	mcp23009e	0x20	8-bit I/O expander (D-PAD)
VL53L1X	vl53l1x	0x29	Time-of-Flight distance sensor
APDS-9960	apds9960	0x39	Proximity, gesture, color, light
HTS221	hts221	0x5F	Humidity + temperature
WSEN-HIDS	wsen-hids	0x5F	Humidity + temperature
WSEN-PADS	wsen-pads	0x5D	Pressure + temperature
ISM330DL	ism330dl	0x6B	6-axis IMU (accel + gyro)
LIS2MDL	lis2mdl	0x1E	3-axis magnetometer
IM34DT05	im34dt05 (not yet implemented)	— (PDM)	Digital microphone
BME280	bme280 (not yet implemented)	0x76	Pressure + humidity + temperature
GC9A01	gc9a01 (not yet implemented)	— (SPI)	Round color LCD display
STeaMi Config	steami_config	—	Persistent board configuration

Quick start

Prerequisites

• PlatformIO or Arduino IDE
• A STeaMi board

Build with PlatformIO

pio run

Upload to board

pio run --target upload

Examples

List available examples

make list-examples

This prints one ready-to-run target per example, e.g.:

flash-hts221/comfort_index
flash-hts221/dew_point
flash-hts221/read_temperature_humidity
flash-hts221/temperature_alarm

Filter by driver:

make list-examples DRIVER=hts221

Flash an example

Copy any line from make list-examples and run it:

make flash-hts221/dew_point

This builds the example, uploads it to the STeaMi board, and opens the serial monitor at 115200 baud on success.

Capture early serial output

make flash-… opens an interactive monitor, which often misses the first lines printed at boot (the monitor finishes its handshake while the board has already moved past setup()). When you need those lines — e.g. to see whether begin() returned false — swap flash- for capture-:

make capture-hts221/dew_point

This builds and uploads the example like flash-…, but instead of opening miniterm it opens the serial port first, asks OpenOCD to reset the board over CMSIS-DAP, and prints whatever the board sends on stdout for 10 seconds. The output is unbuffered and pipeable:

make capture-hts221/dew_point | grep -i "HTS221"

Override the duration with DURATION=N (in seconds):

make capture-hts221/dew_point DURATION=30

Development

Setup

Requires Python 3 (with venv — on Debian/Ubuntu: sudo apt install python3-venv) and Node.js (for the git hooks tooling).

make setup    # Install npm tooling, git hooks, and PlatformIO (in a local .venv/)

make setup creates a local Python virtualenv in .venv/ and installs PlatformIO there, so no global pip install is required. All make targets (build, upload, test-native, test-hardware) transparently use this local pio.

To use pio directly outside of make, activate the venv first:

source .venv/bin/activate
pio device monitor -b 115200

Available commands

Run make help to see all available targets:

Command	Description
make lint	Run clang-format check
make lint-fix	Auto-fix formatting
make build	Build with PlatformIO
make test-native	Run host-side unit tests (no board required)
make test-hardware	Run on-board unit tests (STeaMi required)
make upload	Upload to board
make clean	Remove build artifacts
make deepclean	Remove everything including node_modules

Git hooks

Git hooks are managed by husky and run automatically on commit:

• commit-msg — validates commit message format via commitlint
• pre-commit — branch name validation, content checks, clang-format on staged files

Troubleshooting uploads

PlatformIO's default uploader on STeaMi is OpenOCD over CMSIS-DAP. On Linux, the most common failure mode is Error: unable to find CMSIS-DAP device (or similar) caused by incomplete udev rules.

Install udev rules

The rules shipped with pyocd only grant access to the CMSIS-DAP v1 HID interface. OpenOCD prefers the CMSIS-DAP v2 bulk interface (accessed via libusb on Linux), which needs a separate rule on the USB subsystem. Install both, and tell ModemManager to stop probing the virtual serial port:

sudo tee /etc/udev/rules.d/60-steami.rules > /dev/null <<'EOF'
# STeaMi / ARM mbed DAPLink
# CMSIS-DAP v2 (bulk interface — used by OpenOCD by default)
SUBSYSTEM=="usb", ATTRS{idVendor}=="0d28", ATTRS{idProduct}=="0204", \
    TAG+="uaccess", ENV{ID_MM_DEVICE_IGNORE}="1"
# CMSIS-DAP v1 (HID fallback — used by pyocd and older OpenOCD)
KERNEL=="hidraw*", ATTRS{idVendor}=="0d28", ATTRS{idProduct}=="0204", \
    TAG+="uaccess"
EOF
sudo udevadm control --reload-rules && sudo udevadm trigger

Then unplug and replug the board.

Fallback: use pyocd instead of OpenOCD

If OpenOCD still fails after the udev rules, pyocd is a drop-in alternative with broader DAPLink firmware compatibility and bundled target definitions:

source .venv/bin/activate
pip install pyocd

Then edit platformio.ini:

upload_protocol = custom
upload_command = pyocd flash --target stm32wb55rgvx $SOURCE

The exact pyocd target name may vary by pack version — run pyocd list --targets | grep -i wb55 to confirm. You may need to install the CMSIS pack first: pyocd pack install stm32wb55.

Check OpenOCD version

PlatformIO bundles its own OpenOCD at ~/.platformio/packages/tool-openocd/bin/openocd. STM32WB55 support has improved across versions — if both remedies above fail, verify the bundled OpenOCD is recent:

~/.platformio/packages/tool-openocd/bin/openocd --version

Contributing

See CONTRIBUTING.md.

License

This project is licensed under the GPL v3 License.

Additional Resources

• STeaMi Official Website
• MicroPython driver library — sister project
• Arduino Documentation