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The i2c bus is used to exchange digital data between a sensor (or an actuator) and a mini-PC such as Raspberry Pi. The i2c bus is also widely used on microcontrollers (Arduino, ESP8266, ESP32). By default, the i2c bus is not enabled on the Raspbian distribution. We will activate it and install the necessary tools.
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Activate the i2c bus with the raspi-config tool
Log in as SSH (read this tutorial to learn how to do it) or open a Terminal and run the Raspbian configuration tool.
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sudo raspi-config |
Choose option (5) Interfacing Options
Then in the list the option (P5) I2C. Activate by selecting YES. No to disable.
It is necessary to restart the Raspberry Pi to take the change into account.
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sudo reboot |
Installing i2c Tools
First, make an update to the system.
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sudo apt update sudo apt upgrade -y |
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sudo apt-get install -y python-smbus i2c-tools |
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pi@raspberrypi:~ $ lsmod | grep i2c_ i2c_bcm2835 6433 0 i2c_dev 6642 0 |
I2c pins on the Raspberry GPIO
The i2c pins are located on pins 3 (SDA) and 5 (SCL).
If you are starting with the Raspberry Pi, I recommend that you obtain a breadboard adapter on which the pins are already located. Pin 1 of the GPIO is symbolized by a square.
Plug and test an i2c device with Raspberry Py
To illustrate this tutorial, I have BH1750 brightness sensor (GY-302 from CJMCU) presented in this article. Any other i2c sensor will do the trick. By default, the BH1750 has the address 0x23.
Check the device address with i2cdetect
The i2cdetect command lets you know the device address on the i2c bus. The i2c bus connects up to 255 devices. Depending on the version of the Raspberry Pi, the control is different. For Pi 3 and Pi 2 (models A, B, B +) and Pi Zero, run
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sudo i2cdetect -y 1 |
For older models, run
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sudo i2cdetect -y 0 |
If an error occurs, you will get the following message
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Error: Could not open file `/dev/i2c-0' or `/dev/i2c/0': No such file or directory |
Here’s what you should get. The BH1750 is at the expected address.
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pi@raspberrypi:~ $ sudo i2cdetect -y 1 0 1 2 3 4 5 6 7 8 9 a b c d e f 00: -- -- -- -- -- -- -- -- -- -- -- -- -- 10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 20: -- -- -- 23 -- -- -- -- -- -- -- -- -- -- -- -- 30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 70: -- -- -- -- -- -- -- -- |
So, everything is ready to use i2c sensors in your python, C ++ or Node-RED programs.
- Activate the i2c bus of Raspberry Pi 3 or Pi Zero W
- How to solder the Raspberry Pi Zero W GPIO connector
- Share file from an Orange Pi (Armbian) or a Raspberry Pi (Raspbian) with Samba
- Raspberry Pi Zero W and Node-RED MQTT Surveillance Camera for Home Assistant
- Install Node-RED on Raspbian Jessie Lite on a Raspberry Pi Zero W
- Scratch 2 and Thonny Python for Raspberry Pi (Raspbian 2017-06-21)
