![\"Raspberry](\"https:\/\/i0.wp.com\/randomnerdtutorials.com\/wp-content\/uploads\/2024\/03\/Raspberry-Pi-Pico-MQTT-Guide-MicroPython.jpg?resize=1200%2C675&quality=100&strip=all&ssl=1\")
<\/figure><\/div>\n\n\nNew to the Raspberry Pi Pico?<\/strong> Get started with the Raspberry Pi Pico here<\/a>.<\/p>\n\n\n\n Table of Contents:<\/strong><\/p>\n\n\n\n Throughout this guide we’ll cover the following topics:<\/p>\n\n\n\n Before proceeding, make sure you check the following prerequisites:<\/p>\n\n\n\n To follow this tutorial you need MicroPython firmware installed in your Raspberry Pi Pico board. You also need an IDE to write and upload the code to your board.<\/p>\n\n\n\n The recommended MicroPython IDE for the Raspberry Pi Pico is Thonny IDE. Follow the next tutorial to learn how to install Thonny IDE, flash MicroPython firmware, and upload code to the board.<\/p>\n\n\n\n To follow the examples in 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> Already familiar with MQTT?<\/strong> Jump to the next section<\/a>.<\/p>\n\n\n\n MQTT stands for Message Queuing Telemetry Transport. MQTT is a simple messaging protocol designed for constrained devices with low bandwidth. So, it\u2019s the perfect solution to exchange data between multiple IoT devices. MQTT communication works as a publish<\/em> and subscribe<\/em> system. Devices can publish <\/em>messages on a specific topic. All devices that are subscribed<\/em> to that topic receive the message.<\/p>\n\n\n Its main applications include sending messages to control outputs, reading and publishing data from sensor nodes, and much more.<\/p>\n\n\n\n In MQTT, there are a few basic concepts that you need to understand:<\/p>\n\n\n\n The first concept is the publish<\/strong> and subscribe<\/strong><\/em> system. In a publish and subscribe system, a device can publish a message on a topic or be subscribed to a particular topic to receive messages.<\/p>\n\n\n Messages<\/em> are the information that you want to exchange between your devices. It can be a message like a command to control an output or data like sensor readings.<\/p>\n\n\n\n Another important concept is the topics<\/em>. Topics are the way you register interest in incoming messages or how you specify where you want to publish the message.<\/p>\n\n\n\n Topics are represented with strings separated by a forward slash. Each forward slash indicates a topic level. Here\u2019s an example of how you would create a topic for a lamp in your home office:<\/p>\n\n\n Note:<\/strong> topics are case-sensitive, which makes the following topics different.<\/p>\n\n\n If you would like to turn on a lamp in your home office using MQTT you can imagine the following scenario:<\/p>\n\n\n The device that is publishing the messages can be another microcontroller board, or a Home Automation controller platform with MQTT support like Node-RED, Home Assistant, Adafruit IO, Domoticz, or OpenHAB, for example.<\/p>\n\n\n\n Finally, another important concept is the broker<\/em>.<\/p>\n\n\n\n The MQTT broker is responsible for receiving all messages, filtering the messages, deciding who is interested in them, and then publishing the message to all subscribed clients.<\/p>\n\n\n There are several brokers you can use. For example:<\/p>\n\n\n\n In summary:<\/p>\n\n\n\n To use MQTT, you need an MQTT broker. The broker receives all MQTT messages and sends them to all subscribed clients.<\/p>\n\n\n\n There are many MQTT broker solutions you can use. Here we\u2019ll describe the ones we\u2019re more familiar with:<\/p>\n\n\n\n For simplicity, in this guide we\u2019ll use HiveMQ because you don\u2019t need to install or configure anything like in the Mosquitto MQTT broker. You just need to create an account, set up a cluster and you\u2019re ready to go. Alternatively, if you want to use Mosquitto broker or any other broker of your choice, don\u2019t worry. The code will be compatible with any broker as long as you fill in the right broker details.<\/p>\n\n\n\n Regardless of the MQTT broker you use, you need to have the MQTT URL, username, and password before proceeding to the following sections.<\/p>\n\n\n\n In this section, we\u2019ll show you how to set up your HiveMQ MQTT broker.<\/p>\n\n\n\n 1)<\/strong> First, you need to create an account. Go to hivemq.com<\/a> and click on Start free<\/strong>.<\/p>\n\n\n\n 2)<\/strong> Choose the HiveMQ Cloud plan<\/strong>.<\/p>\n\n\n 3)<\/strong> Login or create a new account and fill in the details to complete your profile.<\/p>\n\n\n\n 4)<\/strong> You should have a new cluster created by default. Click on Manage Cluster<\/strong>.<\/p>\n\n\n 5)<\/strong> Copy the Cluster URL to a safe place because you\u2019ll need it later.<\/p>\n\n\n 6)<\/strong> Click on the Access Management<\/strong> tab at the top.<\/p>\n\n\n\n 7)<\/strong> Fill in the form with a username and password. You\u2019ll need to remember these details later to connect to the MQTT broker. Set the permission to Publish and Subscribe<\/em>.<\/p>\n\n\n\n 8)<\/strong> Finally, click Create Credential<\/strong>.<\/p>\n\n\n If your credentials are successfully created, your MQTT broker is set up.<\/p>\n\n\n Make sure you have the following information before proceeding to the next section:<\/p>\n\n\n\n To write code in MicroPython to use the MQTT communication protocol, we\u2019ll use two MQTT modules: umqtt.simply.py<\/em>, and umqtt.robust.py<\/em>.<\/p>\n\n\n\n Follow the next steps to upload the modules to your Raspberry Pi Pico.<\/p>\n\n\n\n With the Raspberry Pi Pico connected to your computer and with a connection established with Thonny IDE, go to View<\/strong> > Files<\/strong>.<\/p>\n\n\n A new sidebar will show up with all the files on the Raspberry Pi Pico filesystem.<\/p>\n\n\n\n Right-click on the Raspberry Pi Pico sidebar and click on New directory\u2026<\/strong><\/p>\n\n\n\n This new directory should be called umqtt<\/em><\/strong>. Click Ok<\/strong>.<\/p>\n\n\n The new directory will show up on the left sidebar.<\/p>\n\n\n Right-click on the umqtt <\/em>folder and select New file\u2026<\/strong><\/p>\n\n\n\n That new file should be called simple.py<\/em>.<\/p>\n\n\n Copy the simple.py<\/em> code into that new file. The code can be found on the link below:<\/p>\n\n\n\n View raw code<\/a><\/p>\n\n\n\n After copying the code to the simple.py<\/em> file, save the code.<\/p>\n\n\n\n Now, if you expand the umqtt <\/em>folder, you\u2019ll see that the simple.py<\/em> file is there.<\/p>\n\n\n Right-click again on the umqtt<\/em> folder and create another file by clicking on New file\u2026<\/strong><\/p>\n\n\n\n This new file should be called robust.py<\/em>.<\/p>\n\n\n Copy the robust.py<\/em> code into that new file. The code can be found on the link below:<\/p>\n\n\n\n View raw code<\/a><\/p>\n\n\n\n After copying the code to the robust.py<\/em> file, save the code. At this moment, you should have the umqtt<\/em> folder with the simple.py<\/em> and robust.py<\/em> files inside.<\/p>\n\n\n The modules required for MQTT were successfully uploaded to the Raspberry Pi Pico.<\/p>\n\n\n\n We\u2019ll create a configuration file to save the SSID, password, and your MQTT broker details: URL, username, and password.<\/p>\n\n\n\n Create a new file called config.py<\/em> on Thonny IDE and copy the following code:<\/p>\n\n\n View raw code<\/a><\/p>\n\n\n\n Replace the variables with your own details.<\/p>\n\n\n\n If you’re using a local Mosquitto MQTT broker<\/a>, you should pass the broker IP address without the port. For example:<\/p>\n\n\n\n Then, go to File<\/strong> > Save as…<\/strong> and select Raspberry Pi Pico<\/strong>. Save the file as config.py<\/em> (overwrite any existing files with the same name). This file should be saved on the root of the Raspberry Pi Pico and not <\/strong>inside the umqtt <\/em>folder.<\/p>\n\n\n\n In this example, you\u2019ll learn how to publish MQTT messages on a certain topic with your Raspberry Pi Pico. As an example, we\u2019ll publish temperature, humidity, and pressure readings from a BME280 sensor. Alternatively, you can use any other sensor or random values to test the project and concepts.<\/p>\n\n\n\n Before proceeding, make sure that:<\/strong><\/p>\n\n\n\n\n
Prerequisites<\/h2>\n\n\n\n
MicroPython Firmware<\/h3>\n\n\n\n
\n
Parts Required<\/h3>\n\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\n
\n\n\n\nIntroducing MQTT<\/h2>\n\n\n\n
![\"MQTT](\"https:\/\/i0.wp.com\/randomnerdtutorials.com\/wp-content\/uploads\/2018\/09\/Publish-subscribe-MQTT.png?resize=268%2C149&quality=100&strip=all&ssl=1\")
<\/figure><\/div>\n\n\nMQTT Basic Concepts<\/h2>\n\n\n\n
\n
Publish\/Subscribe<\/h3>\n\n\n\n
![\"Publish](\"https:\/\/i0.wp.com\/randomnerdtutorials.com\/wp-content\/uploads\/2018\/09\/Publish-Subscribe-Topic-MQTT.png?resize=743%2C125&quality=100&strip=all&ssl=1\")
<\/figure><\/div>\n\n\n\n
MQTT Messages<\/h3>\n\n\n\n
Topics<\/h3>\n\n\n\n
![\"MQTT](\"https:\/\/i0.wp.com\/randomnerdtutorials.com\/wp-content\/uploads\/2017\/01\/5mqtt-topics.jpg?resize=442%2C246&quality=100&strip=all&ssl=1\")
<\/figure><\/div>\n\n\n![\"MQTT](\"https:\/\/i0.wp.com\/randomnerdtutorials.com\/wp-content\/uploads\/2017\/01\/7case-sensitive-300x188.jpg?resize=300%2C188&quality=100&strip=all&ssl=1\")
<\/figure><\/div>\n\n\n![\"Raspberry](\"https:\/\/i0.wp.com\/randomnerdtutorials.com\/wp-content\/uploads\/2024\/03\/MQTT-Example-Raspberry-Pi-Pico-Subscribe.png?resize=750%2C307&quality=100&strip=all&ssl=1\")
<\/figure><\/div>\n\n\n\n
Broker<\/h3>\n\n\n\n
![\"MQTT](\"https:\/\/i0.wp.com\/randomnerdtutorials.com\/wp-content\/uploads\/2017\/01\/mqtt_broker.png?resize=750%2C303&quality=100&strip=all&ssl=1\")
<\/figure><\/div>\n\n\n\n
\n
Set Up the MQTT Broker<\/h2>\n\n\n\n
MQTT Broker Solutions<\/h3>\n\n\n\n
\n
Setting Up the HiveMQ MQTT Broker<\/h3>\n\n\n\n
![\"HiveMQ](\"https:\/\/i0.wp.com\/randomnerdtutorials.com\/wp-content\/uploads\/2024\/03\/hivemq-free-plan.png?resize=750%2C488&quality=100&strip=all&ssl=1\")
<\/figure><\/div>\n\n\n![\"HiveMQ](\"https:\/\/i0.wp.com\/randomnerdtutorials.com\/wp-content\/uploads\/2024\/03\/HiveMQT-manage-cluster-1.png?resize=750%2C349&quality=100&strip=all&ssl=1\")
<\/figure><\/div>\n\n\n![\"HiveMQ](\"https:\/\/i0.wp.com\/randomnerdtutorials.com\/wp-content\/uploads\/2024\/03\/HiveMQ-cluster-url-1.png?resize=750%2C532&quality=100&strip=all&ssl=1\")
<\/figure><\/div>\n\n\n![\"HiveMQ](\"https:\/\/i0.wp.com\/randomnerdtutorials.com\/wp-content\/uploads\/2024\/03\/HiveMQ-create-credential.png?resize=750%2C389&quality=100&strip=all&ssl=1\")
<\/figure><\/div>\n\n\n![\"username](\"https:\/\/i0.wp.com\/randomnerdtutorials.com\/wp-content\/uploads\/2024\/03\/HiveMQ-credentials-created.png?resize=750%2C120&quality=100&strip=all&ssl=1\")
<\/figure><\/div>\n\n\n\n
\n
Installing MQTT MicroPython Modules<\/h2>\n\n\n\n
![\"Thonny](\"https:\/\/i0.wp.com\/randomnerdtutorials.com\/wp-content\/uploads\/2024\/03\/thonny-ide-view-files.png?resize=750%2C428&quality=100&strip=all&ssl=1\")
<\/figure><\/div>\n\n\n![\"Thonny](\"https:\/\/i0.wp.com\/randomnerdtutorials.com\/wp-content\/uploads\/2024\/03\/Thonny-IDE-Create-directory-umqtt.png?resize=257%2C170&quality=100&strip=all&ssl=1\")
<\/figure><\/div>\n\n\n![\"Thonny](\"https:\/\/i0.wp.com\/randomnerdtutorials.com\/wp-content\/uploads\/2024\/03\/umqtt-folder-created-Thonny-IDE.png?resize=750%2C288&quality=100&strip=all&ssl=1\")
<\/figure><\/div>\n\n\n![\"Thonny](\"https:\/\/i0.wp.com\/randomnerdtutorials.com\/wp-content\/uploads\/2024\/03\/create-umqtt-simple-file.png?resize=738%2C421&quality=100&strip=all&ssl=1\")
<\/figure><\/div>\n\n\n\n
# forked from: https:\/\/github.com\/micropython\/micropython-lib\/tree\/master\/micropython\/umqtt.simple\nimport usocket as socket\nimport ustruct as struct\nfrom ubinascii import hexlify\n\n\nclass MQTTException(Exception):\n pass\n\n\nclass MQTTClient:\n def __init__(\n self,\n client_id,\n server,\n port=0,\n user=None,\n password=None,\n keepalive=0,\n ssl=False,\n ssl_params={},\n ):\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 ssl\n\n self.sock = ssl.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 return op\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\t![\"Thonny](\"https:\/\/i0.wp.com\/randomnerdtutorials.com\/wp-content\/uploads\/2024\/03\/install-MQTT-libraries-simple-py-created.png?resize=750%2C321&quality=100&strip=all&ssl=1\")
<\/figure><\/div>\n\n\n![\"create](\"https:\/\/i0.wp.com\/randomnerdtutorials.com\/wp-content\/uploads\/2024\/03\/install-libraries-MQTT-Thonny-IDE-robust-py.png?resize=192%2C155&quality=100&strip=all&ssl=1\")
<\/figure><\/div>\n\n\n\n
# forked from: https:\/\/github.com\/micropython\/micropython-lib\/tree\/master\/micropython\/umqtt.robust\nimport utime\nfrom . import simple\n\n\nclass MQTTClient(simple.MQTTClient):\n DELAY = 2\n DEBUG = False\n\n def delay(self, i):\n utime.sleep(self.DELAY)\n\n def log(self, in_reconnect, e):\n if self.DEBUG:\n if in_reconnect:\n print("mqtt reconnect: %r" % e)\n else:\n print("mqtt: %r" % e)\n\n def reconnect(self):\n i = 0\n while 1:\n try:\n return super().connect(False)\n except OSError as e:\n self.log(True, e)\n i += 1\n self.delay(i)\n\n def publish(self, topic, msg, retain=False, qos=0):\n while 1:\n try:\n return super().publish(topic, msg, retain, qos)\n except OSError as e:\n self.log(False, e)\n self.reconnect()\n\n def wait_msg(self):\n while 1:\n try:\n return super().wait_msg()\n except OSError as e:\n self.log(False, e)\n self.reconnect()\n\n def check_msg(self, attempts=2):\n while attempts:\n self.sock.setblocking(False)\n try:\n return super().wait_msg()\n except OSError as e:\n self.log(False, e)\n self.reconnect()\n attempts -= 1\n<\/code><\/pre>\n\t![\"MQTT](\"https:\/\/i0.wp.com\/randomnerdtutorials.com\/wp-content\/uploads\/2024\/03\/umqtt-modules-installed-successfully-thonny-ide.png?resize=750%2C279&quality=100&strip=all&ssl=1\")
<\/figure><\/div>\n\n\nCreating a Configuration File<\/h2>\n\n\n\n
wifi_ssid = 'REPLACE_WITH_YOUR_SSID'\nwifi_password = 'REPLACE_WITH_YOUR_PASSWORD'\nmqtt_server = b'MQTT_BROKER_URL'\nmqtt_username = b'BROKER_USERNAME'\nmqtt_password = b'BROKER_PASSWORD'\n<\/code><\/pre>\n\tmqtt_server = b'192.168.1.79'<\/code><\/pre>\n\n\n\nPublishing MQTT Messages<\/h2>\n\n\n\n
\n