Wondering what's the weather? Let's check it out with your Raspberry Pi! This tutorial provides step by step instructions how to detect temperature and humidity with the dirt cheap I2C sensor HTU21D and open source code on your Raspberry Pi.
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Step 1: Getting Ready
For this tutorial you need the following hardware components:
- Raspberry Pi (any model or version)
- HTU21 module
- Male to female jumper wires (x4)
- microSD card with Raspian GNU/Linux distribution
- Power supply
HTU21 (or SHT21) modules are popular for hobby electronics. In general they are available for less than 5 USD per unit.
I have a couple modules here. They have different colors but the sensor is actually absolutely the same on both modules. Beware that the other physical difference is the position of the lines for data and clock. I am going to use the blue HTU21D module for the rest of the tutorial.
Step 2: Wiring
The wiring is simple and takes less than a minute. As shown in the video, using male to female jumper wires connect VIN, GND, SCL and SDA from HTU21D to pins 1, 9, 5, 3 of Raspberry Pi.
Step 3: Installing Software
Boot your Raspberry Pi with Raspbian GNU/Linux distribution, open a terminal or login via SSH. Execute the following commands to download and install the required packages:
sudo apt-get update sudo apt-get install git build-essential i2c-tools
Step 4: Enabling I2C
- Type the following command in a terminal:
- Select Advanced Options > I2C
- Follow the on screen instructions and reboot Raspberry Pi to compete this step.
Step 5: Reading Temperature and Humidity
I have published free and open source example for reading temperature and humidity on Raspberry Pi using HTU21D. They are available in GitHub. Perform the following steps to use it:
- Get the source code from GitHub
git clone https://github.com/leon-anavi/rpi-examples.git
- Build the example:
cd rpi-examples cd HTU21D/c make
- Run the application:
- The temperature and the humidity will be printed on the screen
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