SENSORS/ACTUATORS

Raspberry Pi Pico - Temperature Sensor - LCD

This guide shows you how to use a Raspberry Pi Pico to read the temperature from a DS18B20 temperature sensor and show it on an LCD I2C 16X2 display.

Hardware Preparation

1	×	Raspberry Pi Pico W
1	×	Raspberry Pi Pico (Alternatively)
1	×	Micro USB Cable
1	×	LCD I2C
1	×	DS18B20 Temperature Sensor (WITH Adapter)
1	×	DS18B20 Temperature Sensor (WITHOUT Adapter)
1	×	Jumper Wires
1	×	Breadboard
1	×	(Optional) Screw Terminal Expansion Board for Raspberry Pi Pico

Or you can buy the following sensor kits:

1	×	DIYables Sensor Kit (30 sensors/displays)
1	×	DIYables Sensor Kit (18 sensors/displays)

Disclosure: Some of the links provided in this section are Amazon affiliate links. We may receive a commission for any purchases made through these links at no additional cost to you.
Additionally, some of these links are for products from our own brand, DIYables.

Buy Note: Many DS18B20 sensors available in the market are unreliable. We strongly recommend buying the sensor from the DIYables brand using the link provided above. We tested it, and it worked reliably.

Overview of Temperature Sensor and LCD

Discover how to use temperature sensors and LCDs. Learn about their pin connections, uses, and how to program them by following the tutorials linked below:

Wiring Diagram

This image is created using Fritzing. Click to enlarge image

Raspberry Pi Pico Code

""" This Raspberry Pi Pico MicroPython code was developed by newbiely.com This Raspberry Pi Pico code is made available for public use without any restriction For comprehensive instructions and wiring diagrams, please visit: https://newbiely.com/tutorials/raspberry-pico/raspberry-pi-pico-temperature-sensor-lcd """ import machine import onewire import ds18x20 import time from machine import I2C, Pin from DIYables_MicroPython_LCD_I2C import LCD_I2C ds_pin = machine.Pin(28) # The Raspberry Pi Pico pin GP28 connected to the DS18B20 sensor # Create the onewire object OneWire = onewire.OneWire(ds_pin) # Create the DS18X20 object DS18B20 = ds18x20.DS18X20(OneWire) # Scan for devices on the bus sensor_addresses = OneWire.scan() if not sensor_addresses: raise Exception("No DS18B20 sensor found!") sensor_address = sensor_addresses[0] print('Found DS18B20 sensor with address: ', sensor_address) # The I2C address of your LCD (Update if different) I2C_ADDR = 0x27 # Use the address found using the I2C scanner # Define the number of rows and columns on your LCD LCD_ROWS = 2 LCD_COLS = 16 # Initialize I2C i2c = I2C(0, sda=Pin(0), scl=Pin(1), freq=400000) # Initialize LCD lcd = LCD_I2C(i2c, I2C_ADDR, LCD_ROWS, LCD_COLS) # Setup function lcd.backlight_on() lcd.clear() # Custom character for the degree symbol degree_char = chr(0xDF) # Main loop to read and print the temperature every second while True: DS18B20.convert_temp() time.sleep_ms(750) temperature = DS18B20.read_temp(sensor_address) print('Temperature: {:.2f} °C'.format(temperature)) lcd.clear() lcd.set_cursor(0, 0) # Move to the beginning of the first row lcd.print("Temp: {:.2f}{}C".format(temperature, degree_char)) time.sleep(1)

※ NOTE THAT:

Depending on the manufacturer, the I2C address for the LCD can vary. In our example, we used address 0x27 as specified by the manufacturer, DIYables.

Detailed Instructions

Please follow these instructions step by step:

Ensure that Thonny IDE is installed on your computer.
Ensure that MicroPython firmware is installed on your Raspberry Pi Pico.
If this is your first time using a Raspberry Pico, refer to the Raspberry Pi Pico - Getting Started tutorial for detailed instructions.
Connect the Raspberry Pi Pico to the DS18B20 temperature sensor and LCD I2C according to the provided diagram.
Connect the Raspberry Pi Pico to your computer using a USB cable.
Launch the Thonny IDE on your computer.
On Thonny IDE, select MicroPython (Raspberry Pi Pico) Interpreter by navigating to Tools Options.
In the Interpreter tab, select MicroPython (Raspberry Pi Pico) from the drop-down menu.
Ensure the correct port is selected. Thonny IDE should automatically detect the port, but you may need to select it manually (e.g., COM3 on Windows or /dev/ttyACM0 on Linux).
Navigate to the Tools Manage packages on the Thonny IDE.
Search “DIYables-MicroPython-LCD-I2C”, then find the LCD I2C library created by DIYables.
Click on DIYables-MicroPython-LCD-I2C, then click Install button to install LCD I2C library.

Copy the above code and paste it to the Thonny IDE's editor.
Save the script to your Raspberry Pi Pico by:

Click the Save button, or use Ctrl+S keys.
In the save dialog, you will see two sections: This computer and Raspberry Pi Pico. Select Raspberry Pi Pico
Save the file as main.py

Click the green Run button (or press F5) to run the script. The script will execute.
Check out the message in the Shell at the bottom of Thonny.

Shell x

>>> %Run -c $EDITOR_CONTENT

MPY: soft reboot MPY: soft reboot Found DS18B20 devices: [bytearray(b'(\xffP\x05.\x04\x00\x07')] Temperature: 26.07 °C Temperature: 26.11 °C Temperature: 26.11 °C Temperature: 26.24 °C Temperature: 27.44 °C Temperature: 29.10 °C Temperature: 29.86 °C Temperature: 30.24 °C Temperature: 30.39 °C

MicroPython (Raspberry Pi Pico) • Board CDC @ COM29 ≡

Put the sensor on hot or cold water, or hold it in your hand.
Look at the display on the LCD screen.

If the LCD screen is blank, please visit Troubleshooting for LCD I2C for help.

If you name your script main.py and save it to the root directory of the Raspberry Pi Pico, it will automatically run each time the Pico is powered on or reset. This is useful for standalone applications that need to start running immediately upon power-up. If you name your script another name other than main.py, you will need to manually run it from Thonnys's Shell.

Code Explanation

Look at the comments in the source code for explanations of each line!

Video Tutorial

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