"""
This module provides functionality to read humidity and temperature values from the AM2320 or DHT20 sensors using the Adafruit libraries.
The CachedSensor class caches the readings for 2 seconds to avoid redundant reads.
"""
import time
import board
import adafruit_ahtx0
import adafruit_am2320
import os
class CachedSensor:
"""
Base class for sensors that caches the readings for a specified duration.
"""
def __init__(self, sensor, cache_duration=2):
"""
Initialize the CachedSensor object.
:param sensor: Sensor object
:param cache_duration: Duration to cache the sensor reading, default is 2 seconds
"""
self._sensor = sensor
self._cache_duration = cache_duration
self._last_read_time = 0
self._cached_humidity = None
self._cached_temperature = None
def _read_humidity(self):
"""
Fetch the humidity reading. Needs to be implemented by subclasses.
"""
raise NotImplementedError
def _read_temperature(self):
"""
Fetch the temperature reading. Needs to be implemented by subclasses.
"""
raise NotImplementedError
def get_humidity(self):
"""
Get the cached humidity reading. If the cached value is older than the cache duration,
fetch a new reading.
:return: Humidity reading (float)
"""
current_time = time.time()
if current_time - self._last_read_time > self._cache_duration or self._cached_humidity is None:
self._cached_humidity = self._read_humidity()
self._cached_temperature = self._read_temperature()
self._last_read_time = current_time
return self._cached_humidity
def get_temperature(self):
"""
Get the cached temperature reading. If the cached value is older than the cache duration,
fetch a new reading.
:return: Temperature reading (float)
"""
current_time = time.time()
if current_time - self._last_read_time > self._cache_duration or self._cached_temperature is None:
self._cached_humidity = self._read_humidity()
self._cached_temperature = self._read_temperature()
self._last_read_time = current_time
return self._cached_temperature
class HumidityTemperatureSensor(CachedSensor):
"""
Sensor class for reading humidity and temperature values.
"""
def _read_humidity(self):
"""
Fetch the humidity reading from the sensor.
:return: Humidity value (float)
"""
return self._sensor.relative_humidity
def _read_temperature(self):
"""
Fetch the temperature reading from the sensor.
:return: Temperature value (float)
"""
return self._sensor.temperature
humidity_temperature_sensor = None
def main(sensor_type):
try:
i2c = board.I2C()
# Initialize the sensor based on sensor_type
if sensor_type == "DHT20":
try:
base_sensor = adafruit_ahtx0.AHTx0(i2c, address=0x38)
humidity_temperature_sensor = HumidityTemperatureSensor(base_sensor)
print("DHT20 sensor initialized.")
except Exception as e:
print(f"Failed to initiate DHT20 sensor: {e}")
raise e
elif sensor_type == "AM2320":
try:
base_sensor = adafruit_am2320.AM2320(i2c)
humidity_temperature_sensor = HumidityTemperatureSensor(base_sensor)
print("AM2320 sensor initialized.")
except Exception as e:
print(f"Failed to initiate AM2320 sensor: {e}")
raise e
else:
print(f"Unknown sensor type specified: {sensor_type}")
raise ValueError(f"Unsupported sensor type: {sensor_type}")
except Exception as e:
print(f"Error initializing sensors: {e}")
if humidity_temperature_sensor:
try:
humidity = humidity_temperature_sensor.get_humidity()
temperature = humidity_temperature_sensor.get_temperature()
print(f"humidity, value={humidity:.2f}")
print(f"temperature, value={temperature:.2f}")
except Exception as e:
print(f"Error: {e}")
except KeyboardInterrupt:
print("Script interrupted.")
else:
print("No humidity sensor available.")
if __name__ == "__main__":
sensor_type = "AM2320"
main(sensor_type)```
Need to create setup script to update .env with correct sensor.
ideally during setup we detect the whether AM2320 or DHT20, then we set
TEMP_HUMIDTY_SENSOR_TYPEin.env, which is consumed by config.pyhttps://github.com/iot-root/garden-of-eden/blob/main/.env-dist
https://github.com/iot-root/garden-of-eden/blob/main/config.py
Example code for env variable switch