Hacky Temperature and Humidity Sensor This is a quick, cheap project to create a temperature and humidity sensor using a DHT22 sensor and a Raspberry Pi Pico 4 January 2025 3 minute read By Kevin McAleer Share this article on Table of Contents Why Hacky?Bill of MaterialsWiringCodeWeatherproofingWeatherproof boxCloser viewPresenting the dataNode-REDGrafana Dashboard Tags: dht22 raspberry pi pico pico micropython Difficulty: beginner Category: pico micropython Home Blog Hacky temperature and humidity sensor Hacky Temperature and Humidity Sensor This is a quick, cheap project to create a temperature and humidity sensor using a DHT22 sensor and a Raspberry Pi Pico 4 January 2025 | 3 minute read | By Kevin McAleer | Share this article on This is a quick project to create a temperature and humidity sensor using a DHT22 sensor and a Raspberry Pi Pico. The DHT22 sensor is a low-cost sensor that can measure temperature and humidity. The Raspberry Pi Pico is a microcontroller board that is based on the RP2040 microcontroller chip. The DHT22 sensor is connected to the Raspberry Pi Pico using a single data wire. The data wire is connected to a GPIO pin on the Raspberry Pi Pico. The Raspberry Pi Pico reads the data from the DHT22 sensor and then sends the data to a computer over a WiFi connection to an MQTT server. This can then be monitored using another Raspberry Pi running Node-Red and data stored in a time serries database such as InfluxDB, and finally graphed in a dashboard using Grafana. Why Hacky? I call this a Hacky project simply because the DHT22 is out of production and is not particularly accurate or reliable, but it’s often good enough in a pinch. However, it is a fun project and a good way to learn about microcontrollers and sensors. Bill of Materials Item Description Quantity Price Total Raspberry Pi Pico W Microcontroller board 1 £5.80 £5.80 DHT22 Sensor Temperature and humidity sensor 1 £3.00 £3.00 Jumper Wires 3 female to female jumper wires 3 £0.10 £0.30 Total    £9.10 Wiring The DHT22 sensor has 4 pins: VCC, GND, DATA, and NC. The VCC pin is connected to the 3.3V pin on the Raspberry Pi Pico, the GND pin is connected to the GND pin on the Raspberry Pi Pico, and the DATA pin is connected to GPIO pin 15 on the Raspberry Pi Pico. The NC (Not Connected) pin is not connected. Code The code for this project is written in MicroPython. The code reads the temperature and humidity data from the DHT22 sensor and then sends the data to an MQTT server. The code uses the umqtt.simple library to connect to the MQTT server and publish the data. Copy the main.py to the pico along with simple.py. You’ll also need to create a wifi_config.py file with your WiFi credentials, and upload that to the pico too. Weatherproofing You use this sensor outdoors, add I used a weatherproof box to house the sensor. I cut a hole in the box for the USB cable to exit, and this goes through a hole in front of the robotlab. I added some hotglue to prevent water ingress. Weatherproof box Closer view Presenting the data I used Node-Red to collect the data from the MQTT server and store it in InfluxDB. I then used Grafana to create a dashboard to display the data. I know this last bit is a bit light on detail - I’ll be sure to add more detail in a future post, along with courses on Node-Red, InfluxDB, and Grafana. Node-RED Grafana Dashboard Liked this article? You might like these too. Operation Pico Build a Raspberry Pi Pico version of the classic Operation game Motion Controlled Arm In this project, we will build a motion controlled robotic arm using a Raspberry Pi and a camera Electric Trombone In this project, we will build an electric trombone using a Raspberry Pi Pico as a MIDI controller. Yukon & Omnibot 3000 Meet the Omnibot 3000, a Pimoroni Yukon powered Omnibot 2000. This is a work-in-progress project, so somethings may change! Omnibot 3000 This is a work-in-progress project, so somethings may change! Pico W Toothbrush A 3D Printed Raspberry Pi Pico powered toothbrush you can build and program yourself
Hacky Temperature and Humidity Sensor This is a quick, cheap project to create a temperature and humidity sensor using a DHT22 sensor and a Raspberry Pi Pico 4 January 2025 3 minute read By Kevin McAleer Share this article on Table of Contents Why Hacky?Bill of MaterialsWiringCodeWeatherproofingWeatherproof boxCloser viewPresenting the dataNode-REDGrafana Dashboard Tags: dht22 raspberry pi pico pico micropython Difficulty: beginner Category: pico micropython
This is a quick project to create a temperature and humidity sensor using a DHT22 sensor and a Raspberry Pi Pico. The DHT22 sensor is a low-cost sensor that can measure temperature and humidity. The Raspberry Pi Pico is a microcontroller board that is based on the RP2040 microcontroller chip. The DHT22 sensor is connected to the Raspberry Pi Pico using a single data wire. The data wire is connected to a GPIO pin on the Raspberry Pi Pico. The Raspberry Pi Pico reads the data from the DHT22 sensor and then sends the data to a computer over a WiFi connection to an MQTT server. This can then be monitored using another Raspberry Pi running Node-Red and data stored in a time serries database such as InfluxDB, and finally graphed in a dashboard using Grafana. Why Hacky? I call this a Hacky project simply because the DHT22 is out of production and is not particularly accurate or reliable, but it’s often good enough in a pinch. However, it is a fun project and a good way to learn about microcontrollers and sensors. Bill of Materials Item Description Quantity Price Total Raspberry Pi Pico W Microcontroller board 1 £5.80 £5.80 DHT22 Sensor Temperature and humidity sensor 1 £3.00 £3.00 Jumper Wires 3 female to female jumper wires 3 £0.10 £0.30 Total    £9.10 Wiring The DHT22 sensor has 4 pins: VCC, GND, DATA, and NC. The VCC pin is connected to the 3.3V pin on the Raspberry Pi Pico, the GND pin is connected to the GND pin on the Raspberry Pi Pico, and the DATA pin is connected to GPIO pin 15 on the Raspberry Pi Pico. The NC (Not Connected) pin is not connected. Code The code for this project is written in MicroPython. The code reads the temperature and humidity data from the DHT22 sensor and then sends the data to an MQTT server. The code uses the umqtt.simple library to connect to the MQTT server and publish the data. Copy the main.py to the pico along with simple.py. You’ll also need to create a wifi_config.py file with your WiFi credentials, and upload that to the pico too. Weatherproofing You use this sensor outdoors, add I used a weatherproof box to house the sensor. I cut a hole in the box for the USB cable to exit, and this goes through a hole in front of the robotlab. I added some hotglue to prevent water ingress. Weatherproof box Closer view Presenting the data I used Node-Red to collect the data from the MQTT server and store it in InfluxDB. I then used Grafana to create a dashboard to display the data. I know this last bit is a bit light on detail - I’ll be sure to add more detail in a future post, along with courses on Node-Red, InfluxDB, and Grafana. Node-RED Grafana Dashboard