Sensor error recovery

[r00tat]

Is your feature request related to a problem? Please describe. After some time the ds18b module fails to read the sensor data. From that point in time the sensor is gone and only a restart helps.

This is the error:

2021-03-29 01:05:20 mqtt_io.server [ERROR] Exception in task: <Task finished coro=<MqttIo._init_sensor_inputs.<locals>.poll_sensor() done, defined at /home/pi/rainpi/mqtt-io/mqtt-io/mqtt_io/server.py:528> exception=SensorNotReadyError('Sensor 0120327903dd is not yet ready to read temperature')>:
Traceback (most recent call last):
  File "/home/pi/rainpi/mqtt-io/mqtt-io/mqtt_io/server.py", line 1041, in _remove_finished_transient_tasks
    raise exception
  File "/home/pi/rainpi/mqtt-io/mqtt-io/mqtt_io/server.py", line 533, in poll_sensor
    value = await sensor_module.async_get_value(sens_conf)
  File "/home/pi/rainpi/mqtt-io/mqtt-io/mqtt_io/modules/sensor/__init__.py", line 57, in async_get_value
    return await loop.run_in_executor(ThreadPoolExecutor(), self.get_value, sens_conf)
  File "/usr/lib/python3.7/concurrent/futures/thread.py", line 57, in run
    result = self.fn(*self.args, **self.kwargs)
  File "/home/pi/rainpi/mqtt-io/mqtt-io/mqtt_io/modules/sensor/ds18b.py", line 41, in get_value
    return cast(float, self.sensor.get_temperature())
  File "/home/pi/.local/lib/python3.7/site-packages/w1thermsensor/core.py", line 267, in get_temperature
    raw_temperature_line = self.get_raw_sensor_strings()[1]
  File "/home/pi/.local/lib/python3.7/site-packages/w1thermsensor/core.py", line 250, in get_raw_sensor_strings
    raise SensorNotReadyError(self)
w1thermsensor.errors.SensorNotReadyError: Sensor 0120327903dd is not yet ready to read temperature

Describe the solution you'd like If a sensor can't be read, there should be an exponential backoff retrying the read on the sensor.

Describe alternatives you've considered I've implemented a simple ds18b replacement based on the w1_therm kernel module and the 1wire sys files:

"""
DS18S20/DS1822/DS18B20/DS1825/DS28EA00/MAX31850K temperature sensors
make sure w1_therm and w1_gpio modules are loaded to use this sensor
"""
import os
import os.path

from ...types import ConfigType, SensorValueType
from . import GenericSensor

REQUIREMENTS = ()
ALLOWED_TYPES = ["DS18S20", "DS1822", "DS18B20", "DS1825", "DS28EA00", "MAX31850K"]
CONFIG_SCHEMA = {
    "file": dict(type="string", required=True, empty=False),
}

class Sensor(GenericSensor):
    """
    Implementation of Sensor class for the one wire temperature sensors. DS18B etc.
    """

    def setup_module(self) -> None:
        self.file_path = f"/sys/bus/w1/devices/{self.config['file']}/temperature"
        if not os.path.isfile(self.file_path):
            raise FileNotFoundError(
                (f"unable to locate 1wire temperature file under {self.file_path}. "
                 f"Make sure the w1_therm and w1_gpio kernel modules are loaded"))

    def get_value(self, sens_conf: ConfigType) -> SensorValueType:
        """
        Get the temperature value from the sensor
        """
        with open(self.file_path, 'r') as raw_file:
            raw_value = raw_file.read()
        return float(raw_value) / 1000

Additional context

This is my config.yaml:

sensor_modules:
  - name: ds18b20
    module: ds18b
    type: DS18B20
    address: 0120327903dd
sensor_inputs:
  - name: rainpi_temp2
    module: ds18b20
    interval: 60
    digits: 2
    ha_discovery:
      name: Rainpi temperature 1wire
      device_class: temperature
      unit_of_measurement: "°C"

[flyte]

Yep, sensor read errors should not cause the sensor read loop to stop.

I've committed a change including a backoff to the develop branch. Would you mind testing it out and seeing if it solves your issue?

[r00tat]

Sure, I'll deploy it in the evening and let you know, if this solves the issue!

Thanks a lot!

[r00tat]

Hi @flyte, it seems like backoff did solve my sensor issue and I do not see any errors in the log any more.

Thanks for your quick response and fix!