![\"MicroPython](\"https:\/\/i0.wp.com\/randomnerdtutorials.com\/wp-content\/uploads\/2020\/04\/ESP32-ESP8266-DHT11-DHT22-MQTT-MicroPython.jpg?resize=1200%2C675&quality=100&strip=all&ssl=1\")
<\/figure><\/div>\n\n\n\nRecommended reading:<\/strong> What is MQTT and How It Works<\/a> <\/p>\n\n\n\n Note: <\/strong> this tutorial is compatible with both the ESP32 and ESP8266 development boards.<\/em><\/p>\n\n\n\n The following diagram shows a high-level overview of the project we’ll build.<\/p>\n\n\n\n Before continuing with this tutorial, make sure you complete the following prerequisites:<\/p>\n\n\n\n To follow this tutorial you need MicroPython firmware installed in your ESP32 or ESP8266 boards. You also need an IDE to write and upload the code to your board. We suggest using Thonny IDE or uPyCraft IDE:<\/p>\n\n\n\n To use MQTT, you need a broker. We’ll be using Mosquitto broker<\/a> installed on a Raspberry Pi. Read How to Install Mosquitto Broker on Raspberry Pi<\/a>.<\/p>\n\n\n\n If you’re not familiar with MQTT make sure you read our introductory tutorial: What is MQTT and How It Works<\/a><\/p>\n\n\n\n For this tutorial you need the following parts:<\/p>\n\n\n\n You can use the preceding links or go directly to MakerAdvisor.com\/tools<\/a> to find all the parts for your projects at the best price!<\/p> To use MQTT with the ESP32\/ESP8266 and MicroPython, we’ll use the umqttsimple<\/em>.py library. Follow the next set of instructions for the IDE you’re using:<\/p>\n\n\n\n View raw code<\/a><\/p>\n\n\n\n 1.<\/strong> Create a new file by pressing the New File<\/strong> button.<\/p>\n\n\n\n 2.<\/strong> Copy the umqttsimple<\/em> library code into it. You can access the umqttsimple<\/em> library code in the following link:<\/p>\n\n\n\n 3.<\/strong> Save the file by pressing the Save<\/strong> button.<\/p>\n\n\n\n 4.<\/strong> Call this new file \u201cumqttsimple.py<\/strong>\u201d and press ok<\/strong>.<\/p>\n\n\n\n 5.<\/strong> Click the Download and Run<\/strong> button.<\/p>\n\n\n\n 6.<\/strong> The file should be saved on the device<\/em> folder with the name \u201cumqttsimple.py<\/strong>\u201d as highlighted in the figure below.<\/p>\n\n\n\n Now, you can use the library functionalities in your code by importing the library.<\/p>\n\n\n\n 1.<\/strong> Copy the library code to a new file. The umqttsimple library code can be found here<\/a>.<\/p>\n\n\n\n 2.<\/strong> Go to File<\/strong> > Save as…<\/strong><\/p>\n\n\n\n If the “Save as…” menu is missing, check that you have properly set up Thonny IDE as in the following tutorial:<\/p>\n\n\n\n 3.<\/strong> Select save to “MicroPython device<\/strong>“:<\/p>\n\n\n\n 4.<\/strong> Name your file as umqttsimple.py<\/em> and press the OK button:<\/p>\n\n\n\n And that’s it. The library was uploaded to your board. To make sure that it was uploaded successfully, go to File > Save as… and select the MicroPython device. Your file should be listed there:<\/p>\n\n\n\n After uploading the library to your board, you can use the library functionalities in your code by importing the library.<\/p>\n\n\n\n Wire the DHT22 or DHT11<\/a> sensor to the ESP32 development board as shown in the following schematic diagram. <\/p>\n\n\n\n In this example, we\u2019re connecting the DHT data pin to GPIO 14<\/span>. However, you can use any other suitable digital pin. <\/p>\n\n\n\n Learn how to use the ESP32 GPIOs with our guide: ESP32 Pinout Reference: Which GPIO pins should you use?<\/a> <\/p>\n\n\n\n If you’re using an ESP8266 NodeMCU, follow the next diagram instead.<\/p>\n\n\n\n In this example, we\u2019re connecting the DHT data pin to GPIO 14<\/span> (D5). However, you can use any other suitable digital pin.<\/p>\n\n\n\n Learn how to use the ESP8266 GPIOs with our guide: ESP8266 Pinout Reference: Which GPIO pins should you use?<\/a><\/p>\n\n\n\n After uploading the library to the ESP32 or ESP8266, copy the following code to the main.py<\/em> file. It publishes the temperature and humidity on the esp\/dht\/temperature<\/strong> and esp\/dht\/humidity<\/strong> topics every 5 seconds.<\/p>\n\n\n View raw code<\/a><\/p>\n\n\n\n Import the following libraries:<\/p>\n\n\n\n In the following variables, you need to enter your network credentials and your broker IP address.<\/p>\n\n\n\n For example, our broker IP address is: 192.168.1.106.<\/p>\n\n\n\n Note:<\/strong> read this tutorial<\/a> to see how to get your broker IP address.<\/p>\n\n\n\n To create an MQTT client, we need to get the ESP unique ID. That\u2019s what we do in the following line (it is saved on the client_id<\/span> variable).<\/p>\n\n\n\n Next, create the topics you want your ESP to be publishing in. In our example, it will publish temperature on the esp\/dht\/temperature<\/strong> topic and humidity on the esp\/dht\/humidity<\/strong> topic.<\/p>\n\n\n\n Then, create the following variables:<\/p>\n\n\n\n The last_message<\/span> variable will hold the last time a message was sent. The message_interval<\/span> is the time between each message sent. Here, we\u2019re setting it to 5 seconds (this means a new message will be sent every 5 seconds). You can change it, if you want. <\/p>\n\n\n\n After that, connect the ESP to your local network.<\/p>\n\n\n\n Initialize the DHT sensor by creating a dht<\/span> instance on GPIO 4<\/span> as follows:<\/p>\n\n\n\n If you\u2019re using a DHT11 sensor, uncomment the next line, and comment the previous one:<\/p>\n\n\n\n The connect_mqtt()<\/span> function creates an MQTT Client and connects to your broker.<\/p>\n\n\n\n If your MQTT broker requires username and password, you should use the following line to pass your broker username and password as arguments.<\/p>\n\n\n\n The restart_and_reconnect()<\/span> function resets the ESP32\/ESP8266 board. This function will be called if we’re not able to publish the readings via MQTT in case the broker disconnects.<\/p>\n\n\n\n We created a function called read_sensor()<\/span> that returns the current temperature and humidity from the DHT sensor and handles any exceptions, in case we’re not able to get readings from the sensor.<\/p>\n\n\n\n In the while loop, we publish new temperature and humidity readings every 5 seconds.<\/p>\n\n\n\n First, we check if it is time to get new readings:<\/p>\n\n\n\n If it is, request new readings from the DHT sensor by calling the read_sensor()<\/span> function. The temperature is saved on the temp<\/span> variable and the humidity is saved on the hum<\/span> variable.<\/p>\n\n\n\n Finally, publish the readings by using the publish()<\/span> method on the client<\/span> object. The publish()<\/span> method accepts as arguments the topic and the message, as follows:<\/p>\n\n\n\n Finally, update the time when the last message was sent:<\/p>\n\n\n\n In case the ESP32 or ESP8266 disconnects from the broker, and we’re not able to publish the readings, call the restart_and_reconnect()<\/span> function to reset the ESP board and try to reconnect to the broker.<\/p>\n\n\n\n After uploading the code, you should get new sensor readings on the shell every 5 seconds.<\/p>\n\n\n\n Now, go to the next section to prepare Node-RED to receive the readings the ESP is publishing.<\/p>\n\n\n\n The ESP32 or ESP8266 is publishing temperature readings every 5 seconds on the esp\/dht\/temperature<\/strong> and esp\/dht\/humidity<\/strong> topics. Now, you can use any dashboard that supports MQTT or any other device that supports MQTT to subscribe to those topics and receive the readings.<\/p>\n\n\n\n As an example, we’ll create a simple flow using Node-RED to subscribe to those topics and display the readings on gauges.<\/p>\n\n\n\n If you don’t have Node-RED installed, follow the next tutorials:<\/p>\n\n\n\n Having Node-RED running on your Raspberry Pi, go to your Raspberry Pi IP address followed by :1880.<\/p>\n\n\n\n The Node-RED interface should open. Drag two MQTT in nodes, and two gauge nodes to the flow.<\/p>\n\n\n\n Click the MQTT node and edit its properties.<\/p>\n\n\n\n The Server field refers to the MQTT broker. In our case, the MQTT broker is the Raspberry Pi, so it is set to localhost:1883. If you’re using a Cloud MQTT broker, you should change that field. <\/p>\n\n\n\n Insert the topic you want to be subscribed to and the QoS. This previous MQTT node is subscribed to the esp\/dht\/temperature<\/strong> topic. <\/p>\n\n\n\n Click on the other MQTT in node and edit its properties with the same server, but for the other topic: esp\/dht\/humidity<\/strong>. <\/p>\n\n\n\n Click on the gauge nodes and edit its properties for each reading. The following node is set for the temperature readings. Edit the other chart node for the humidity readings.<\/p>\n\n\n\n Wire your nodes as shown below:<\/p>\n\n\n\n Finally, deploy your flow (press the button on the upper right corner).<\/p>\n\n\n\n Alternatively, you can go to Menu <\/strong>> Import <\/strong>and copy the following to your Clipboard<\/strong> to create your Node-RED flow.<\/p>\n\n\n View raw code<\/a><\/p>\n\n\n\n Go to your Raspberry Pi IP address followed by :1880\/ui<\/em>.<\/p>\n\n\n\n You should get access to the current DHT temperature and humidity readings on the Dashboard. You can use other dashboard-type nodes to display the readings on different ways.<\/p>\n\n\n\n That’s it! You have your ESP32 or ESP8266 boards publishing DHT temperature and humidity readings to Node-RED via MQTT using MicroPython.<\/p>\n\n\n\n MQTT is a great communication protocol to exchange small amounts of data between IoT devices. In this tutorial you\u2019ve learned how to publish temperature and humidity readings from a DHT sensor with the ESP32 and ESP8266 using MicroPython to different MQTT topics. Then, you can use any device or home automation platform to subscribe to those topics and receive the readings.<\/p>\n\n\n\n Instead of a DHT11 or DHT22 sensor<\/a>, you can use any other sensor like a DS18B20 temperature sensor<\/a> or BME280 sensor<\/a>.<\/p>\n\n\n\n We have other projects\/tutorials related with the DHT sensor that you may also like:<\/p>\n\n\n\nProject Overview<\/h2>\n\n\n\n
![\"DHT](\"https:\/\/i0.wp.com\/randomnerdtutorials.com\/wp-content\/uploads\/2020\/04\/DHT-ESP32-ESP8266-MicroPython-MQTT-Project-Overview-f.png?resize=890%2C628&quality=100&strip=all&ssl=1\")
<\/figure>\n\n\n\nPrerequisites<\/h2>\n\n\n\n
MQTT Broker<\/h3>\n\n\n\n
![\"Mosquitto](\"https:\/\/i0.wp.com\/randomnerdtutorials.com\/wp-content\/uploads\/2017\/01\/mosquitto-broker.png?resize=200%2C197&quality=100&strip=all&ssl=1\")
<\/figure><\/div>\n\n\n\nParts Required<\/h3>\n\n\n\n
![](\"https:\/\/i0.wp.com\/randomnerdtutorials.com\/wp-content\/uploads\/2017\/10\/header-200.png?w=1200&quality=100&strip=all&ssl=1\")
<\/a><\/p>\n\n\n\numqtttsimple Library<\/h2>\n\n\n\n
try:\n import usocket as socket\nexcept:\n import socket\nimport ustruct as struct\nfrom ubinascii import hexlify\n\nclass MQTTException(Exception):\n pass\n\nclass MQTTClient:\n\n def __init__(self, client_id, server, port=0, user=None, password=None, keepalive=0,\n ssl=False, ssl_params={}):\n if port == 0:\n port = 8883 if ssl else 1883\n self.client_id = client_id\n self.sock = None\n self.server = server\n self.port = port\n self.ssl = ssl\n self.ssl_params = ssl_params\n self.pid = 0\n self.cb = None\n self.user = user\n self.pswd = password\n self.keepalive = keepalive\n self.lw_topic = None\n self.lw_msg = None\n self.lw_qos = 0\n self.lw_retain = False\n\n def _send_str(self, s):\n self.sock.write(struct.pack("!H", len(s)))\n self.sock.write(s)\n\n def _recv_len(self):\n n = 0\n sh = 0\n while 1:\n b = self.sock.read(1)[0]\n n |= (b & 0x7f) << sh\n if not b & 0x80:\n return n\n sh += 7\n\n def set_callback(self, f):\n self.cb = f\n\n def set_last_will(self, topic, msg, retain=False, qos=0):\n assert 0 <= qos <= 2\n assert topic\n self.lw_topic = topic\n self.lw_msg = msg\n self.lw_qos = qos\n self.lw_retain = retain\n\n def connect(self, clean_session=True):\n self.sock = socket.socket()\n addr = socket.getaddrinfo(self.server, self.port)[0][-1]\n self.sock.connect(addr)\n if self.ssl:\n import ussl\n self.sock = ussl.wrap_socket(self.sock, **self.ssl_params)\n premsg = bytearray(b"\\x10\\0\\0\\0\\0\\0")\n msg = bytearray(b"\\x04MQTT\\x04\\x02\\0\\0")\n\n sz = 10 + 2 + len(self.client_id)\n msg[6] = clean_session << 1\n if self.user is not None:\n sz += 2 + len(self.user) + 2 + len(self.pswd)\n msg[6] |= 0xC0\n if self.keepalive:\n assert self.keepalive < 65536\n msg[7] |= self.keepalive >> 8\n msg[8] |= self.keepalive & 0x00FF\n if self.lw_topic:\n sz += 2 + len(self.lw_topic) + 2 + len(self.lw_msg)\n msg[6] |= 0x4 | (self.lw_qos & 0x1) << 3 | (self.lw_qos & 0x2) << 3\n msg[6] |= self.lw_retain << 5\n\n i = 1\n while sz > 0x7f:\n premsg[i] = (sz & 0x7f) | 0x80\n sz >>= 7\n i += 1\n premsg[i] = sz\n\n self.sock.write(premsg, i + 2)\n self.sock.write(msg)\n #print(hex(len(msg)), hexlify(msg, ":"))\n self._send_str(self.client_id)\n if self.lw_topic:\n self._send_str(self.lw_topic)\n self._send_str(self.lw_msg)\n if self.user is not None:\n self._send_str(self.user)\n self._send_str(self.pswd)\n resp = self.sock.read(4)\n assert resp[0] == 0x20 and resp[1] == 0x02\n if resp[3] != 0:\n raise MQTTException(resp[3])\n return resp[2] & 1\n\n def disconnect(self):\n self.sock.write(b"\\xe0\\0")\n self.sock.close()\n\n def ping(self):\n self.sock.write(b"\\xc0\\0")\n\n def publish(self, topic, msg, retain=False, qos=0):\n pkt = bytearray(b"\\x30\\0\\0\\0")\n pkt[0] |= qos << 1 | retain\n sz = 2 + len(topic) + len(msg)\n if qos > 0:\n sz += 2\n assert sz < 2097152\n i = 1\n while sz > 0x7f:\n pkt[i] = (sz & 0x7f) | 0x80\n sz >>= 7\n i += 1\n pkt[i] = sz\n #print(hex(len(pkt)), hexlify(pkt, ":"))\n self.sock.write(pkt, i + 1)\n self._send_str(topic)\n if qos > 0:\n self.pid += 1\n pid = self.pid\n struct.pack_into("!H", pkt, 0, pid)\n self.sock.write(pkt, 2)\n self.sock.write(msg)\n if qos == 1:\n while 1:\n op = self.wait_msg()\n if op == 0x40:\n sz = self.sock.read(1)\n assert sz == b"\\x02"\n rcv_pid = self.sock.read(2)\n rcv_pid = rcv_pid[0] << 8 | rcv_pid[1]\n if pid == rcv_pid:\n return\n elif qos == 2:\n assert 0\n\n def subscribe(self, topic, qos=0):\n assert self.cb is not None, "Subscribe callback is not set"\n pkt = bytearray(b"\\x82\\0\\0\\0")\n self.pid += 1\n struct.pack_into("!BH", pkt, 1, 2 + 2 + len(topic) + 1, self.pid)\n #print(hex(len(pkt)), hexlify(pkt, ":"))\n self.sock.write(pkt)\n self._send_str(topic)\n self.sock.write(qos.to_bytes(1, "little"))\n while 1:\n op = self.wait_msg()\n if op == 0x90:\n resp = self.sock.read(4)\n #print(resp)\n assert resp[1] == pkt[2] and resp[2] == pkt[3]\n if resp[3] == 0x80:\n raise MQTTException(resp[3])\n return\n\n # Wait for a single incoming MQTT message and process it.\n # Subscribed messages are delivered to a callback previously\n # set by .set_callback() method. Other (internal) MQTT\n # messages processed internally.\n def wait_msg(self):\n res = self.sock.read(1)\n self.sock.setblocking(True)\n if res is None:\n return None\n if res == b"":\n raise OSError(-1)\n if res == b"\\xd0": # PINGRESP\n sz = self.sock.read(1)[0]\n assert sz == 0\n return None\n op = res[0]\n if op & 0xf0 != 0x30:\n return op\n sz = self._recv_len()\n topic_len = self.sock.read(2)\n topic_len = (topic_len[0] << 8) | topic_len[1]\n topic = self.sock.read(topic_len)\n sz -= topic_len + 2\n if op & 6:\n pid = self.sock.read(2)\n pid = pid[0] << 8 | pid[1]\n sz -= 2\n msg = self.sock.read(sz)\n self.cb(topic, msg)\n if op & 6 == 2:\n pkt = bytearray(b"\\x40\\x02\\0\\0")\n struct.pack_into("!H", pkt, 2, pid)\n self.sock.write(pkt)\n elif op & 6 == 4:\n assert 0\n\n # Checks whether a pending message from server is available.\n # If not, returns immediately with None. Otherwise, does\n # the same processing as wait_msg.\n def check_msg(self):\n self.sock.setblocking(False)\n return self.wait_msg()\n<\/code><\/pre>\n\tA. Upload umqttsimple library with uPyCraft IDE<\/h3>\n\n\n\n
![\"\"](\"https:\/\/i0.wp.com\/randomnerdtutorials.com\/wp-content\/uploads\/2018\/10\/uPycraft-ide-tools-menu-new-file.png?resize=135%2C41&quality=100&strip=all&ssl=1\")
<\/figure><\/div>\n\n\n\n![\"\"](\"https:\/\/i0.wp.com\/randomnerdtutorials.com\/wp-content\/uploads\/2018\/10\/uPycraft-ide-tools-menu-save-file.png?resize=142%2C47&quality=100&strip=all&ssl=1\")
<\/figure><\/div>\n\n\n\n![\"\"](\"https:\/\/i0.wp.com\/randomnerdtutorials.com\/wp-content\/uploads\/2018\/12\/import-umqttsimple-library.png?resize=750%2C305&quality=100&strip=all&ssl=1\")
<\/figure><\/div>\n\n\n\n![\"\"](\"https:\/\/i0.wp.com\/randomnerdtutorials.com\/wp-content\/uploads\/2018\/10\/uPycraft-ide-tools-menu-download-and-run.png?resize=238%2C45&quality=100&strip=all&ssl=1\")
<\/figure><\/div>\n\n\n\n![\"\"](\"https:\/\/i0.wp.com\/randomnerdtutorials.com\/wp-content\/uploads\/2018\/12\/umqttsimple-library-installed.png?resize=750%2C468&quality=100&strip=all&ssl=1\")
<\/figure><\/div>\n\n\n\nB. Upload umqttsimple library with Thonny IDE<\/h3>\n\n\n\n
![\"Thonny](\"https:\/\/i0.wp.com\/randomnerdtutorials.com\/wp-content\/uploads\/2020\/10\/Thonny-IDE-ESP32-ESP8266-MicroPython-Save-file-library-to-device-save-as.png?resize=206%2C294&quality=100&strip=all&ssl=1\")
<\/figure><\/div>\n\n\n\n![\"Thonny](\"https:\/\/i0.wp.com\/randomnerdtutorials.com\/wp-content\/uploads\/2020\/10\/Thonny-IDE-ESP32-ESP8266-MicroPython-Save-file-library-to-device-select.png?resize=220%2C202&quality=100&strip=all&ssl=1\")
<\/figure><\/div>\n\n\n\n![\"umqttsimple](\"https:\/\/i0.wp.com\/randomnerdtutorials.com\/wp-content\/uploads\/2020\/10\/umqttsimple-library-new-MicroPython-file-Thonny-IDE.png?resize=553%2C263&quality=100&strip=all&ssl=1\")
<\/figure><\/div>\n\n\n\n![\"umqttsimple](\"https:\/\/i0.wp.com\/randomnerdtutorials.com\/wp-content\/uploads\/2020\/10\/umqttsimple-library-MicroPython-file-created-Thonny-IDE.png?resize=553%2C289&quality=100&strip=all&ssl=1\")
<\/figure><\/div>\n\n\n\n Schematic: ESP32 with DHT11\/DHT22<\/h2>\n\n\n\n
![\"MicroPython](\"https:\/\/i0.wp.com\/randomnerdtutorials.com\/wp-content\/uploads\/2019\/04\/dht_esp32_bb-1.png?resize=546%2C683&quality=100&strip=all&ssl=1\")
<\/figure><\/div>\n\n\n\n Schematic: ESP8266 NodeMCU with DHT11\/DHT22 <\/h2>\n\n\n\n
![\"MicroPython](\"https:\/\/i0.wp.com\/randomnerdtutorials.com\/wp-content\/uploads\/2019\/04\/dht_esp8266_bb.png?resize=429%2C674&quality=100&strip=all&ssl=1\")
<\/figure><\/div>\n\n\n\nCode<\/h2>\n\n\n\n
# Complete project details at https:\/\/RandomNerdTutorials.com\/micropython-mqtt-publish-dht11-dht22-esp32-esp8266\/\n\nimport time\nfrom umqttsimple import MQTTClient\nimport ubinascii\nimport machine\nimport micropython\nimport network\nimport esp\nfrom machine import Pin\nimport dht\nesp.osdebug(None)\nimport gc\ngc.collect()\n\nssid = 'REPLACE_WITH_YOUR_SSID'\npassword = 'REPLACE_WITH_YOUR_PASSWORD'\nmqtt_server = '192.168.1.XXX'\n#EXAMPLE IP ADDRESS or DOMAIN NAME\n#mqtt_server = '192.168.1.106'\n\nclient_id = ubinascii.hexlify(machine.unique_id())\n\ntopic_pub_temp = b'esp\/dht\/temperature'\ntopic_pub_hum = b'esp\/dht\/humidity'\n\nlast_message = 0\nmessage_interval = 5\n\nstation = network.WLAN(network.STA_IF)\n\nstation.active(True)\nstation.connect(ssid, password)\n\nwhile station.isconnected() == False:\n pass\n\nprint('Connection successful')\n\nsensor = dht.DHT22(Pin(14))\n#sensor = dht.DHT11(Pin(14))\n\ndef connect_mqtt():\n global client_id, mqtt_server\n client = MQTTClient(client_id, mqtt_server)\n #client = MQTTClient(client_id, mqtt_server, user=your_username, password=your_password)\n client.connect()\n print('Connected to %s MQTT broker' % (mqtt_server))\n return client\n\ndef restart_and_reconnect():\n print('Failed to connect to MQTT broker. Reconnecting...')\n time.sleep(10)\n machine.reset()\n\ndef read_sensor():\n try:\n sensor.measure()\n temp = sensor.temperature()\n # uncomment for Fahrenheit\n #temp = temp * (9\/5) + 32.0\n hum = sensor.humidity()\n if (isinstance(temp, float) and isinstance(hum, float)) or (isinstance(temp, int) and isinstance(hum, int)):\n temp = (b'{0:3.1f},'.format(temp))\n hum = (b'{0:3.1f},'.format(hum))\n return temp, hum\n else:\n return('Invalid sensor readings.')\n except OSError as e:\n return('Failed to read sensor.')\n\ntry:\n client = connect_mqtt()\nexcept OSError as e:\n restart_and_reconnect()\n\nwhile True:\n try:\n if (time.time() - last_message) > message_interval:\n temp, hum = read_sensor()\n print(temp)\n print(hum)\n client.publish(topic_pub_temp, temp)\n client.publish(topic_pub_hum, hum)\n last_message = time.time()\n except OSError as e:\n restart_and_reconnect()\n<\/code><\/pre>\n\tHow the Code Works<\/h2>\n\n\n\n
import time\nfrom umqttsimple import MQTTClient\nimport ubinascii\nimport machine\nimport micropython\nimport network\nimport esp\nfrom machine import Pin\nimport dht\nesp.osdebug(None)\nimport gc\ngc.collect()<\/code><\/pre>\n\n\n\nssid = 'REPLACE_WITH_YOUR_SSID'\npassword = 'REPLACE_WITH_YOUR_PASSWORD'\nmqtt_server = 'REPLACE_WITH_YOUR_MQTT_BROKER_IP'<\/code><\/pre>\n\n\n\nmqtt_server = '192.168.1.106'<\/code><\/pre>\n\n\n\nclient_id = ubinascii.hexlify(machine.unique_id())<\/code><\/pre>\n\n\n\ntopic_pub_temp = b'esp\/dht\/temperature'\ntopic_pub_hum = b'esp\/dht\/humidity'<\/code><\/pre>\n\n\n\nlast_message = 0\nmessage_interval = 5<\/code><\/pre>\n\n\n\nstation = network.WLAN(network.STA_IF)\n\nstation.active(True)\nstation.connect(ssid, password)\n\nwhile station.isconnected() == False:\n pass\n\nprint('Connection successful')<\/code><\/pre>\n\n\n\nsensor = dht.DHT22(Pin(4))<\/code><\/pre>\n\n\n\nsensor = dht.DHT11(Pin(4))<\/code><\/pre>\n\n\n\nConnect to MQTT Broker<\/h3>\n\n\n\n
def connect_mqtt():\n global client_id, mqtt_server\n client = MQTTClient(client_id, mqtt_server)\n #client = MQTTClient(client_id, mqtt_server, user=your_username, password=your_password)\n client.connect()\n print('Connected to %s MQTT broker' % (mqtt_server))\n return client<\/code><\/pre>\n\n\n\nclient = MQTTClient(client_id, mqtt_server, user=your_username, password=your_password)<\/code><\/pre>\n\n\n\nRestart and Reconnect<\/h3>\n\n\n\n
def restart_and_reconnect():\n print('Failed to connect to MQTT broker. Reconnecting...')\n time.sleep(10)\n machine.reset()<\/code><\/pre>\n\n\n\nRead DHT Sensor<\/h3>\n\n\n\n
def read_sensor():\n try:\n sensor.measure()\n temp = sensor.temperature()\n hum = sensor.humidity()\n if (isinstance(temp, float) and isinstance(hum, float)) or (isinstance(temp, int) and isinstance(hum, int)):\n temp = (b'{0:3.1f},'.format(temp))\n hum = (b'{0:3.1f},'.format(hum))\n\n # uncomment for Fahrenheit\n #temp = temp * (9\/5) + 32.0\n return temp, hum\n else:\n return('Invalid sensor readings.')\n except OSError as e:\n return('Failed to read sensor.')<\/code><\/pre>\n\n\n\nPublishing MQTT Messages<\/h3>\n\n\n\n
if (time.time() - last_message) > message_interval:<\/code><\/pre>\n\n\n\ntemp, hum = read_sensor()<\/code><\/pre>\n\n\n\nclient.publish(topic_pub_temp, temp)\nclient.publish(topic_pub_hum, hum)<\/code><\/pre>\n\n\n\nlast_message = time.time()<\/code><\/pre>\n\n\n\nexcept OSError as e:\n restart_and_reconnect()<\/code><\/pre>\n\n\n\nPreparing Node-RED Dashboard<\/h2>\n\n\n\n
http://raspberry-pi-ip-address:1880<\/code><\/pre>\n\n\n\n![\"ESP32](\"https:\/\/i0.wp.com\/randomnerdtutorials.com\/wp-content\/uploads\/2020\/04\/0-ESP32-DHT11-DHT22-Arduino-IDE.png?resize=266%2C103&quality=100&strip=all&ssl=1\")
<\/figure><\/div>\n\n\n\n![\"MQTT](\"https:\/\/i0.wp.com\/randomnerdtutorials.com\/wp-content\/uploads\/2020\/04\/MQTT-In-Node-ESP32-ESP8266-Publish-Temperature-Humidity-Node-RED-Flow.png?resize=504%2C391&quality=100&strip=all&ssl=1\")
<\/figure><\/div>\n\n\n\n![\"ESP32](\"https:\/\/i0.wp.com\/randomnerdtutorials.com\/wp-content\/uploads\/2020\/04\/2-ESP32-Gauge-Temperature-Humidity-Node-RED-Flow.png?resize=497%2C603&quality=100&strip=all&ssl=1\")
<\/figure><\/div>\n\n\n\n![\"ESP32](\"https:\/\/i0.wp.com\/randomnerdtutorials.com\/wp-content\/uploads\/2020\/04\/ESP32-MQTT-Publish-DHT-Temperature-Humidity-Node-RED-Flow.png?resize=469%2C139&quality=100&strip=all&ssl=1\")
<\/figure><\/div>\n\n\n\n![\"Deploy](\"https:\/\/i0.wp.com\/randomnerdtutorials.com\/wp-content\/uploads\/2017\/06\/11_deploy_button.png?resize=138%2C40&quality=100&strip=all&ssl=1\")
<\/figure><\/div>\n\n\n\n[{"id":"59f95d85.b6f0b4","type":"mqtt in","z":"b01416d3.f69f38","name":"","topic":"esp\/dht\/temperature","qos":"1","datatype":"auto","broker":"8db3fac0.99dd48","x":910,"y":340,"wires":[["2babfd19.559212"]]},{"id":"2babfd19.559212","type":"ui_gauge","z":"b01416d3.f69f38","name":"","group":"37de8fe8.46846","order":2,"width":0,"height":0,"gtype":"gage","title":"Temperature","label":"\u00baC","format":"{{value}}","min":0,"max":"40","colors":["#00b500","#f7df09","#ca3838"],"seg1":"","seg2":"","x":1210,"y":340,"wires":[]},{"id":"b9aa2398.37ca3","type":"mqtt in","z":"b01416d3.f69f38","name":"","topic":"esp\/dht\/humidity","qos":"1","datatype":"auto","broker":"8db3fac0.99dd48","x":900,"y":420,"wires":[["d0f75e86.1c9ae"]]},{"id":"d0f75e86.1c9ae","type":"ui_gauge","z":"b01416d3.f69f38","name":"","group":"37de8fe8.46846","order":2,"width":0,"height":0,"gtype":"gage","title":"Humidity","label":"%","format":"{{value}}","min":"30","max":"100","colors":["#53a4e6","#1d78a9","#4e38c9"],"seg1":"","seg2":"","x":1200,"y":420,"wires":[]},{"id":"8db3fac0.99dd48","type":"mqtt-broker","z":"","name":"","broker":"localhost","port":"1883","clientid":"","usetls":false,"compatmode":false,"keepalive":"60","cleansession":true,"birthTopic":"","birthQos":"0","birthPayload":"","closeTopic":"","closeQos":"0","closePayload":"","willTopic":"","willQos":"0","willPayload":""},{"id":"37de8fe8.46846","type":"ui_group","z":"","name":"BME280","tab":"53b8c8f9.cfbe48","order":1,"disp":true,"width":"6","collapse":false},{"id":"53b8c8f9.cfbe48","type":"ui_tab","z":"","name":"Home","icon":"dashboard","order":2,"disabled":false,"hidden":false}]\n<\/code><\/pre>\n\tDemonstration<\/h2>\n\n\n\n
http://raspberry-pi-ip-address:1880\/ui<\/code><\/pre>\n\n\n\n![\"ESP32](\"https:\/\/i0.wp.com\/randomnerdtutorials.com\/wp-content\/uploads\/2020\/04\/4-ESP32-MQTT-Publish-Temperature-Humidity-Node-RED-Dashboard.png?resize=517%2C618&quality=100&strip=all&ssl=1\")
<\/figure><\/div>\n\n\n\nWrapping Up<\/h2>\n\n\n\n