Get full access to Getting Started with Python for the Internet of Things and 60K+ other titles, with a free 10-day trial of O'Reilly.

There are also live events, courses curated by job role, and more.

Start your free trial

I2C bus and level shifting

The I²C bus consists of two wires, one data (SDA), and one clock (SCL). Both are passively pulled to VCC (on the Raspberry Pi, this is 3.3 V) with pull-up resistors. The Raspberry Pi will control the clock by pulling it low every cycle and the data line can be pulled low by Raspberry Pi to send commands or by the connected device to respond with data:

The Raspberry Pi I²C pins include pull-up resistors on SDA and SCL

Since the slave devices can only pull the data line to GND, the device may be powered by 3.3 V or even 5 V without the risk of driving the GPIO pins too high (remember that the Raspberry Pi GPIO is not ...

Get Getting Started with Python for the Internet of Things now with the O’Reilly learning platform.

O’Reilly members experience books, live events, courses curated by job role, and more from O’Reilly and nearly 200 top publishers.

Start your free trial

Don’t leave empty-handed

Get Mark Richards’s Software Architecture Patterns ebook to better understand how to design components—and how they should interact.

It’s yours, free.

Get it now

Check it out now on O’Reilly

Dive in for free with a 10-day trial of the O’Reilly learning platform—then explore all the other resources our members count on to build skills and solve problems every day.

Start your free trial Become a member now