MQTT 到 InfluxDB 只给我 0 个值

Question

currently working on a python code that subscribes to a MQTT topic published by a RaspberryPi hooked up to a BME280 sensor reading for Temperature and Humidity then saves it to a database. I've created the database and my mqtt works after the topic with "MyMQTT" app

Problems start when i try to run it and all i get is 0s in when I try to read the database.

Any ideas?

Publisher code:

import RPi.GPIO as GPIO
import time
import smbus2
import bme280
import paho.mqtt.client as mqtt

mqtt_broker = "test.mosquitto.org"
topic1 = "tp/eng/iotp_project/temp"
topic2 = "tp/eng/iotp_project/hum"

port = 1
address = 0x76
bus = smbus2.SMBus(port)

calibration_params = bme280.load_calibration_params(bus, address)

# Set the GPIO pin numbers for the fan and buzzer
fan = 23
buzzer = 22

# Set the temperature threshold for turning on the fan
fan_threshold = 24

# Set the humidity threshold for turning on the buzzer
buzzer_threshold = 80



# Initialize the GPIO pins
GPIO.setmode(GPIO.BCM)
GPIO.setup(fan, GPIO.OUT)
GPIO.setup(buzzer, GPIO.OUT)

# Initialize the BME280 sensor
sensor = bme280.sample(bus, address, calibration_params)

temp = round(sensor.temperature, 2)
hum = round(sensor.humidity, 2)

def MQTT():
    my_mqtt = mqtt.Client()
    print("\nCreated client object at "+ time.strftime("%H:%M:%S"))
    my_mqtt.connect(mqtt_broker, port=1883)
    print("--connected to broker")
    try:
        my_mqtt.publish(topic1, temp)
        print("--Temperature: %.2f C" % sensor.temperature)
        my_mqtt.publish(topic2, hum)
        print("--Humidity: %.2f %%" % sensor.humidity)
    except:
        print("--publishing error!")
    else:
        my_mqtt.disconnect()
        print("--disconnected from broker")

while True:
    MQTT()

#clean up the GPIO pins
GPIO.cleanup()
GPIO.setwarnings(False)

Subscriber/InfluxDB code:

import argparse
from influxdb import InfluxDBClient
from influxdb.client import InfluxDBClientError
import datetime
import time
import paho.mqtt.client as mqtt

PASSWORD = 'root'
USER = 'root'
DBNAME = 'temperature'
HOST = 'localhost'
mqtt_broker ="test.mosquitto.org"
topic ="tp/iotp_project/temperature"
PORT = 8086
dbclient = None;
temp = 0.0;

def onMessage(client, userdata , message):
    global temp
    time.sleep(2)
    temp = float(message.payload.decode())
    print(temp)

def startMQTT():
    my_mqtt= mqtt.Client()
    my_mqtt.on_message =onMessage
    my_mqtt.connect(mqtt_broker, port = 1883)
    my_mqtt.subscribe(topic)
    my_mqtt.loop_start()

def getSensorData():
    now = time.gmtime()
    pointValues= [
        {
            "time": time.strftime("%Y-%m-%d %H:%M:%S", now),
            "measurement": 'reading',
            "tags": {
                "nodeId": "node_1",
            },
            "fields": {
                "Temperature": temp
            },
        }
    ]

    return(pointValues)

def main():
    startMQTT()
    dbclient = InfluxDBClient(HOST, PORT, USER, PASSWORD, DBNAME)

while True:
    data_point = getSensorData()
    dbclient.write_points(data_point)
    time.sleep(2)

if __name__ == '__main__':
        main()

Current output:

I tried making an if else condition in the def main(): of my subscriber but the result remained the same. was suggested by my classmates to remove any time.sleep() from my publisher codes but that still didn't work. database entries are still at 0 value

Attempted if/else def main():

def main():
        startMQTT()
        dbclient = InfluxDBClient(HOST, PORT, USER, PASSWORD, DBNAME)
        messageReceived = False
        while True:
            if messageReceived:
                data_point1 = getTemperatureData()
                data_point2 = getHumidityData()
                dbclient.write_points(data_point1)
                dbclient.write_points(data_point2)
                time.sleep(5)
            else:
                time.sleep(2)

Answer 1

You should put the sleep back into the publisher (and you should not be creating a new client for each loop).

Your subscriber is failing because you are missing a global temp from the getSensorData() function.

Also remove the time.sleep(2) from onMessage()