Inter-Integrated Circuit (I2C) is a serial communication protocol used to connect electronic components on the same printed circuit board or between different peripherals. On the Raspberry Pi, the I2C bus is a popular method of enabling the board to communicate with various sensors, modules and other external components. I2C uses two wires: SDA, which enables data transmission, and SCL, which transmits the clock between the raspberry pi board and your component.
The Raspberry Pi has dedicated I2C pins for easy connection to external peripherals. This bus enables bidirectional communication between the master (Raspberry Pi) and several slaves (peripherals). Each I2C device has a unique address, enabling the master to select the device with which it wishes to communicate.
Here is where the i2C pins are located on the raspberry pi:
We need to install the i2c-toolfs package to use the i2c on the Raspberry pi board:
We need to install the i2c-toolfs package to use the i2c on the Raspberry pi board:
This is the raspi-config menu. Click on Interface Options:
Once in interface options, click on I2C:
Click yes to activate i2C on the raspberry Pi:
A confirmation window appears:
We’ll now look at how to send data over the i2c to, or receive data from, a device connected to the raspberry pi.
First of all, using the i2cdetect function in the i2c-tools package, you can see which components and their addresses are connected to the raspberry pi’s i2c:
Here you can see our PSTN module connected with address 0x68. You can find the address of your device in its datasheet.
Here’s a program to read values from address 0x68. It reads the minutes, hours and seconds of an RTC module, but can be easily adapted to your needs:
Here’s a second program to send values through the i2c to address 0x10:
Here is the result of the SDA and SCL on the oscilloscope: