MQTT/Python 订阅多个主题并在 Raspberry LCD 上写入有效负载

Question

我是Python和MQTT的新手。我能够编写一些 Python 工作代码来将连接的传感器数据发布到代理，现在我想订阅多个主题并将所有有效负载写入连接到覆盆子的 LCD 20x4 上。

实际上，我编写了一个Python来订阅一个主题并将有效负载写入LCD; 没问题，它正在工作。无法在同一 Python 中包含其他主题并将有效负载写入 LCD 上。

下面你可以找到我的工作Python代码，"只是"一个主题。

#!/usr/bin/python
# -*- coding: utf-8 -*-
#
# RPi-S-LCD.py
# Created on 8/1/2017
#
# Python program that write payloads on LCD 20x4
#
import time
import sys
import os
import paho.mqtt.client as paho
sys.path.append("/home/pi/Adafruit_Python_CharLCD")
import Adafruit_CharLCD as LCD
import Adafruit_GPIO.MCP230xx as MCP
### Define MCP pins connected to LCD
lcd_rs = 6
lcd_en = 4
lcd_d4 = 3
lcd_d5 = 2
lcd_d6 = 1
lcd_d7 = 0
lcd_backlight = None
### Define LCD type
lcd_columns = 20
lcd_rows = 4
### Initialize MCP23017 for LCD
gpiomcp = MCP.MCP23017(0x20, busnum=1)
### Initialize LCD panel parameters
lcd = LCD.Adafruit_CharLCD(lcd_rs, lcd_en, lcd_d4, lcd_d5, lcd_d6, lcd_d7, lcd_columns, lcd_rows, lcd_backlight, gpio=gpiomcp)
lcd.show_cursor(False)
lcd.blink(False)
lcd.clear()
### Read data from MQTT broker
def on_subscribe(client, userdata, mid, granted_qos):
    print("Subscribed to the broker "+str(mid)+" "+str(granted_qos))

### Print topic data to LCD
def on_message1(client, userdata, msg):
    lcd.set_cursor(0,0)
    lcd.message(msg.payload)
client = paho.Client()
client.on_subscribe = on_subscribe
client.on_message = on_message1
client.connect("10.0.2.10", 1883, 30)
client.subscribe("iDomus/Time",2)
client.loop_forever()

Answer 1

阅读有关 MQTT 的更多文档，我找到了该函数

"message_callback_add"

现在 Python 程序运行良好。这就是我的想法。现在我订阅了所有主题，但我选择了我想要处理的特定主题，并且有效载荷是分开的，以便在LCD上轻松可视化。对不起我的蟒蛇代码。我不是程序员，但以下内容对我来说工作正常。希望它可以帮助其他人解决同样的问题。

#!/usr/bin/python
# -*- coding: utf-8 -*-
#
# RPi-S-LCD.py
# Created on 21/1/2017
#
# Python program that use LCD 20x4 to display topics info
#
import time
import sys
import os
import paho.mqtt.client as paho
sys.path.append("/home/pi/Adafruit_Python_CharLCD")
import Adafruit_CharLCD as LCD
import Adafruit_GPIO.MCP230xx as MCP
### Define MCP pins connected to LCD
lcd_rs = 6
lcd_en = 4
lcd_d4 = 3
lcd_d5 = 2
lcd_d6 = 1
lcd_d7 = 0
lcd_backlight = None
### Define LCD type
lcd_columns = 20
lcd_rows = 4
### Initialize MCP23017 for LCD
gpiomcp = MCP.MCP23017(0x20, busnum=1)
### Initialize LCD panel parameters
lcd = LCD.Adafruit_CharLCD(lcd_rs, lcd_en, lcd_d4, lcd_d5, lcd_d6, lcd_d7, lcd_columns, lcd_rows, lcd_backlight, gpio=gpiomcp)
lcd.show_cursor(False)
lcd.blink(False)
lcd.clear()
### DATE
def on_message_date(mosq, obj, msg):
    lcd.set_cursor(0,0)
    lcd.message(str(msg.payload))
### TIME
def on_message_time(mosq, obj, msg):
    lcd.set_cursor(0,2)
    lcd.message(str(msg.payload))
### RELAY
def on_message_relay(mosq, obj, msg):
    if (str(msg.payload)[3]) == '0':
        lcd.set_cursor(7,2)
        lcd.message("RL1= 0 RL2= 0")
    elif (str(msg.payload)[3]) == '1':
        lcd.set_cursor(7,2)
        lcd.message("RL1= 1 RL2= 0")
    elif (str(msg.payload)[3]) == '2':
        lcd.set_cursor(7,2)
        lcd.message("RL1= 0 RL2= 1")
    elif (str(msg.payload)[3]) == '3':
        lcd.set_cursor(7,2)
        lcd.message("RL1= 1 RL2= 1")
    else:
        lcd.set_cursor(7,2)
        lcd.message("RELAYs ERROR!")
### PUBLIC IP
def on_message_pubip(mosq, obj, msg):
    lcd.set_cursor(0,1)
    lcd.message("                    ")
    lcd.set_cursor(0,1)
    lcd.message("IP = "+str(msg.payload)[0:14])
### TEMPERATURE
def on_message_temp(mosq, obj, msg):
    lcd.set_cursor(0,3)
    lcd.message(str(msg.payload)[0:4]+chr(223)+"C")
### HUMIDITY
def on_message_humi(mosq, obj, msg):
    lcd.set_cursor(7,3)
    lcd.message(str(msg.payload)[0:4]+chr(37))
### PRESSURE
def on_message_pres(mosq, obj, msg):
    lcd.set_cursor(13,3)
    lcd.message(str(msg.payload)+"hPa")
### topic message
def on_message(mosq, obj, msg):
    print(msg.topic+" "+str(msg.qos)+" "+str(msg.payload))
mqttc = paho.Client()
#Add message callbacks that will only trigger on a specific   subscription    match
mqttc.message_callback_add('iDomus/Time', on_message_time)
mqttc.message_callback_add('iDomus/Date', on_message_date)
mqttc.message_callback_add('iDomus/PubIPRead', on_message_pubip)
mqttc.message_callback_add('iDomus/RPiS/Sens1/Temp', on_message_temp)
mqttc.message_callback_add('iDomus/RPiS/Sens1/Humi', on_message_humi)
mqttc.message_callback_add('iDomus/RPiN/Sens2/Pres', on_message_pres)
mqttc.message_callback_add('iDomus/RPiS/Rel1/Read', on_message_relay)
mqttc.on_message = on_message
mqttc.connect("10.0.2.10", 1883, 30)
mqttc.subscribe("iDomus/#")
mqttc.loop_forever()

Answer 2

我能够使用 paho python mqtt 库订阅多个主题。我创建了一个主题列表并将其传递给"subscribe.simple"。使用下面的示例程序，我可以订阅"主题 1"和"主题 2"。

topic = ["topic1", "topic2"]
hostname_1 = "<mqtt broker host name>"
port_1 = <mqtt broker connection port>
username_1 = "broker username"
password_1 = "broker password"
message = subscribe.simple(topic, hostname=hostname_1, port=port_1, keepalive=60, will=None, auth={'username':username_1,'password':password_1})
print meaasge.payload