- Use multi-line ensure_python_modules list format in ens210.py,
matching the established pattern from ina219.py
- Fix auto_install_packages indentation in ina219.py docstring
- Remove smbus2 from pyproject.toml core dependencies; sensor packages
are handled at runtime via ensure_python_modules/auto_install_packages
- Update docs/adding_sensors.md template and guidance to match
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
- Add smbus2>=0.4.0 to pyproject.toml core dependencies so it is always
present in the venv rather than relying on runtime auto-install
- Add i2c-tools to apt-get installs in both install and upgrade paths
so /dev/i2c-* devices are accessible and i2cdetect is available for
diagnostics (service user was already being added to the i2c group)
- Switch ENS210 config examples to hex I2C address notation (0x43) to
match datasheets and i2cdetect output; update contributor docs guidance
accordingly
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Adds support for the ENS210 relative humidity and temperature sensor
as a new plug-in under repeater/sensors/ens210.py. Also adds a
commented configuration example to config.yaml.example and a
contributor guide at docs/adding_sensors.md explaining how to add
further sensor plug-ins.
## Implementation notes
### Why smbus2 instead of an Adafruit/CircuitPython library
The ENS210 has no maintained Adafruit CircuitPython driver. The
available third-party options are either unmaintained or bring in the
full Blinka/CircuitPython hardware-abstraction stack as a dependency.
smbus2 is a thin, widely-packaged wrapper around the Linux i2c-dev
kernel interface that is already present on Raspberry Pi OS and most
Debian-based systems. It has no transitive dependencies and adds no
abstraction cost.
The ENS210 protocol is simple enough that direct register access is
preferable: two writes to start a measurement (REG_SENS_RUN + REG_SENS_START)
and two three-byte block reads to retrieve temperature and humidity.
The status/validity bit is checked inline rather than relying on a
library to surface it. There is no value a higher-level driver would
add here.
### Read strategy
A fixed post-trigger delay is unreliable — the sensor datasheet quotes
~130 ms typical conversion time but the actual ready time varies. The
implementation instead polls the data-valid status bit (bit 1 of the
third byte in each register block) every 50 ms for up to
read_timeout_seconds (default 1.0 s), breaking as soon as both T and
H report valid data. This is the same approach used in the validated
reference script.
The I2C bus is opened and closed on every read rather than kept open
across poll cycles. Keeping a persistent SMBus handle caused subsequent
reads to time out, consistent with the Linux i2c-dev file descriptor
accumulating state between transactions.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Joshua Mesilane