dht_to_mqtt.py

#!/usr/bin/env python2
# -*- coding: utf-8 -*-
from __future__ import print_function
import argparse
import random
import time
import Adafruit_DHT
import paho.mqtt.client as mqtt

# generate client ID with pub prefix randomly
# client_id = f'rpi-dht-mqtt-{random.randint(0, 1000)}'
# username = 'emqx'
# password = 'public'

def connect_mqtt(broker, port, client_id):
    def on_connect(client, userdata, flags, rc):
        if rc == 0:
            print("Connected to MQTT Broker!")
        else:
            print("Failed to connect, return code %d\n", rc)

    client = mqtt.Client(client_id)
    # client.username_pw_set(username, password)
    client.on_connect = on_connect
    client.connect(broker, port)
    return client

def publish_to_mqtt(mqtt_client, topic, value):
    result = mqtt_client.publish(topic, value)
    # result: [0, 1]
    
    status = result[0]
    if status == 0:
        print("Send {value} to topic {topic}".format(value=value, topic=topic))
    else:
        print("Failed to send message to topic {topic}".format(value=value, format=format))


def get_sensor_data(gpio_pin):
    """Get sensor data from gpio pin provided in the argument"""
    humid, temp = Adafruit_DHT.read_retry(Adafruit_DHT.AM2302, gpio_pin)
    humidity, temperature = (None, None)

    if humid is not None:
        if abs(humid) < 100:        #If sensor returns veird value ignore it and wait for the next one 
           humidity = '{0:0.1f}'.format(humid)

    if temp is not None:
        if abs(temp) < 100:        #If sensor returns veird value ignore it and wait for the next one 
           temperature = '{0:0.1f}'.format(temp)

    return (humidity, temperature)

if __name__ == '__main__':
    parser = argparse.ArgumentParser()
    parser.add_argument("-p", "--pull_time", type=int, default=5, help="Pull sensor data every X seconds.")
    parser.add_argument("-g", "--gpio", type=int, nargs='+', 
                        help="Set GPIO pin id to listen for DHT sensor data.", 
                        required=True)
    parser.add_argument("-r", "--room", type=str, nargs='+', 
                        help="Set room name.", 
                        required=True)
    parser.add_argument("-m", "--mqtt", type=str, default="", help="Send data to MQTT server at this address.")
    parser.add_argument("-mp", "--mqtt_port", type=int, default=1883, help="MQTT port")
    parser.add_argument("-t", "--topic_prefix", type=str, default="", help="Send data to this MQTT topic prefix (<prefix>-temp, <prefix>-humid).")
    cli_arguments = parser.parse_args()

    if len(cli_arguments.gpio) != len(cli_arguments.room):
        print("The number of gpio pins set needs to be the same as number of rooms set" \
              "\n Number of gpio pins: {g}\n Number of rooms: {r}".format(g=len(cli_arguments.gpio), r=len(cli_arguments.room)))
        exit(1)


    if cli_arguments.topic_prefix!="":
        mqtt_client = connect_mqtt(cli_arguments.mqtt, cli_arguments.mqtt_port, "-".join((cli_arguments.topic_prefix, cli_arguments.room[0])))


    # Update temperature and humidity
    while True:
        for id, gpio_pin in enumerate(cli_arguments.gpio):
            print(gpio_pin)
            humidity, temperature = get_sensor_data(gpio_pin)

            if cli_arguments.topic_prefix!="":
               publish_to_mqtt(mqtt_client, "/".join((cli_arguments.topic_prefix, cli_arguments.room[id], "temperature")), temperature)
               publish_to_mqtt(mqtt_client, "/".join((cli_arguments.topic_prefix, cli_arguments.room[id], "humidity")), humidity)
        time.sleep(cli_arguments.pull_time)


# dht_exporter.py -p 60 -g 4 -r 'balkon' -m x.y.z.w -mp 1883 -t dht_sensor

# dht_sensor/balkon/temperature
# dht_sensor/balkon/humidity