Merge pull request #122 from RoelGo/aht20

Added support for the AHT20 sensor

pi_mqtt_gpio/modules/aht20.py

+from pi_mqtt_gpio.modules import GenericSensor
+
+REQUIREMENTS = ("adafruit-circuitpython-ahtx0",)
+SENSOR_SCHEMA = {
+    "type": dict(
+        type="string",
+        required=False,
+        empty=False,
+        default="temperature",
+        allowed=["temperature", "humidity"],
+    )
+}
+
+
+class Sensor(GenericSensor):
+    """
+    Implementation of Sensor class for aht20.
+    """
+
+    def __init__(self, config):
+        import board
+        import busio
+        import adafruit_ahtx0
+
+        i2c = busio.I2C(board.SCL, board.SDA)
+        self.sensor = adafruit_ahtx0.AHTx0(i2c)
+
+    def setup_sensor(self, config):
+        return True  # nothing to do here
+
+    def get_value(self, config):
+        """get the temperature value from the sensor"""
+        temperature = self.sensor.temperature
+        humidity = self.sensor.relative_humidity
+        if config["type"] == "temperature" and temperature is not None:
+            return temperature
+        if config["type"] == "humidity" and humidity is not None:
+            return humidity
+        return None