Merge pull request #1367 from Joe2824/master

Add DHT20 Humidity/Temperature Sensor

Author: kizniche

CHANGELOG.md

@@ -16,6 +16,7 @@ This release changes the install directory from ~/Mycodo to /opt/Mycodo. This ne
 
 ### Features
 
+ - Add Input: DHT20
  - Add Output: GPIO On/Off using pinctrl (First Pi 5-compatible Output)
  - Add Output: PWM MQTT Publish
  - Add Output: GP8403 2-Channel DAC (0-10 VDC) ([#1354](https://github.com/kizniche/Mycodo/issues/1354))

mycodo/inputs/dht20.py

@@ -0,0 +1,177 @@
+# coding=utf-8
+import copy
+import time
+
+from mycodo.inputs.base_input import AbstractInput
+from mycodo.inputs.sensorutils import calculate_dewpoint
+from mycodo.inputs.sensorutils import calculate_vapor_pressure_deficit
+
+# Measurements
+measurements_dict = {
+    0: {
+        'measurement': 'temperature',
+        'unit': 'C'
+    },
+    1: {
+        'measurement': 'humidity',
+        'unit': 'percent'
+    },
+    2: {
+        'measurement': 'dewpoint',
+        'unit': 'C'
+    },
+    3: {
+        'measurement': 'vapor_pressure_deficit',
+        'unit': 'Pa'
+    }
+}
+
+# Input information
+INPUT_INFORMATION = {
+    'input_name_unique': 'DHT20',
+    'input_manufacturer': 'AOSONG',
+    'input_name': 'DHT20',
+    'input_library': 'smbus2',
+    'measurements_name': 'Humidity/Temperature',
+    'measurements_dict': measurements_dict,
+    'url_datasheet': 'http://www.aosong.com/userfiles/files/media/Data%20Sheet%20DHT20%20%20A1.pdf',
+    'url_product_purchase': [
+        'https://www.seeedstudio.com/Grove-Temperature-Humidity-Sensor-V2-0-DHT20-p-4967.html',
+        'https://www.antratek.de/humidity-and-temperature-sensor-dht20',
+        'https://www.adafruit.com/product/5183'],
+    'url_manufacturer': 'https://asairsensors.com/product/dht20-sip-packaged-temperature-and-humidity-sensor/',
+
+    'options_enabled': [
+        'measurements_select',
+        'period',
+        'pre_output'
+    ],
+
+    'options_disabled': [
+        'interface',
+        'i2c_location',
+    ],
+
+    'dependencies_module': [
+        ('pip-pypi', 'smbus2', 'smbus2==0.4.1')
+    ],
+
+    'interfaces': ['I2C'],
+    'i2c_location': ['0x38'],
+    'self.i2c_address_editable': False,
+}
+
+
+class InputModule(AbstractInput):
+    """
+    This module is a modified version of the DHT20 module from the Mycodo 
+    distribution.
+
+    A sensor support class that measures the DHT20's humidity and temperature
+    and calculates the dew point.
+
+    """
+    def __init__(self, input_dev, testing=False):
+        """
+        Instantiate with the Pi and gpio to which the DHT20 output
+        pin is connected.
+
+        """
+        super().__init__(input_dev, testing=testing, name=__name__)
+
+        self.i2c_address = None
+        self.dht20 = None
+
+        if not testing:
+            self.try_initialize()
+
+    def initialize(self):
+        from smbus2 import SMBus
+
+        # Wait 100ms after power-on
+        time.sleep(0.1)
+
+        self.i2c_address = int(str(self.input_dev.i2c_location), 16)
+        self.dht20 = SMBus(self.input_dev.i2c_bus)
+
+        # Check if Sensor is ready
+        status_word = self.dht20.read_byte(self.self.i2c_address)
+        if status_word != 0x18:
+            buffer = bytearray(b'\x00\x00')
+            # Initialize the 0x1B, 0x1C, 0x1E registers
+            self.dht20.write_i2c_block_data(self.i2c_address, 0x1B, buffer)
+            self.dht20.write_i2c_block_data(self.i2c_address, 0x1C, buffer)
+            self.dht20.write_i2c_block_data(self.i2c_address, 0x1E, buffer)
+            time.sleep(1)
+
+            if self.dht20.read_byte(self.i2c_address) != 0x18:
+                self.logger.error("Could not initialize DHT20.")
+            else:
+                self.logger.debug("Initialize DHT20 successfully.")
+
+    def calculate_crc(self, data):
+        data = data[:-1]
+        crc = 0xFF  # Initial value of CRC
+        polynomial = 0x31  # CRC8 check polynomial: 1 + X^4 + X^5 + X^8
+
+        for byte in data:
+            crc ^= byte  # XOR operation with the current byte
+            for _ in range(8):
+                if crc & 0x80:  # Check if the most significant bit is 1
+                    crc = (crc << 1) ^ polynomial
+                else:
+                    crc <<= 1
+        return crc & 0xFF  # Return only the 8 least significant bits
+
+    def get_measurement(self):
+        """Gets the humidity and temperature
+
+        'temperature': temperature (°C),
+        'raw_temperature': the 'raw' temperature as produced by the ADC,
+        'humidity': relative humidity (%RH),
+        'raw_humidity': the 'raw' relative humidity as produced by the ADC,
+        'crc_ok': indicates if the data was received correctly
+
+        """
+        self.return_dict = copy.deepcopy(measurements_dict)
+
+        time.sleep(0.01)
+        # trigger measurement
+        self.dht20.write_i2c_block_data(self.i2c_address,0xAC,[0x33,0x00])
+        time.sleep(0.08)
+
+        # read measurement data
+        data = self.dht20.read_i2c_block_data(self.i2c_address,0x71,7)
+
+        received_crc = data[-1]
+        crc_ok = self.calculate_crc(data) == received_crc
+
+        if crc_ok:
+            raw_temperature = ((data[3] & 0xf) << 16) + (data[4] << 8) + data[5]
+            temperature = 200*float(raw_temperature)/2**20 - 50
+
+            raw_humidity = ((data[3] & 0xf0) >> 4) + (data[1] << 12) + (data[2] << 4)
+            humidity = 100*float(raw_humidity)/2**20
+
+            self.logger.debug(f"Temperature: {temperature}, Humidity: {humidity}, CRC OK: {crc_ok}")
+
+            if humidity:
+                temp_dew_point = calculate_dewpoint(temperature, humidity)
+                temp_vpd = calculate_vapor_pressure_deficit(temperature, humidity)
+            else:
+                self.logger.error("Could not acquire measurement")
+
+            if temp_dew_point is not None:
+                if self.is_enabled(0):
+                    self.value_set(0, temperature)
+                if self.is_enabled(1):
+                    self.value_set(1, humidity)
+                if self.is_enabled(2):
+                    self.value_set(2, temp_dew_point)
+                if self.is_enabled(3):
+                    self.value_set(3, temp_vpd)
+
+        else:
+            self.logger.error("CRC check was not successfully")
+
+        return self.return_dict