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Spark Fun has a simple breakdown of the various ways to interface 3.3V logic devices to 5V logic devices -

If you’ve ever tried to hook up a 3.3V sensor to a 5V micro, you know what I’m talking about – connecting these two can be a problem! There are several ways in which a 3.3V device can be safely connected to a 5v microcontroller. This tutorial will detail a few ways in which this can be accomplished.

Below is an example of how NOT to connect a 3.3V device (like the SCP1000-D01 pressure sensor with SPI interface) to a 5V microcontroller (like a PIC or AVR running at 5V). Although you may experience normal operating conditions, the lifespan of your 3.3V device will be dramatically shortened.

Spark Fun Electronics – Link.

Phillip Torrone

Editor at large – Make magazine. Creative director – Adafruit Industries, contributing editor – Popular Science. Previously: Founded – Hack-a-Day, how-to editor – Engadget, Director of product development – Fallon Worldwide, Technology Director – Braincraft.



  1. Jetlag says:

    Just a small nit to pick, but what you have pictured is how NOT to connect a 3.3V device to a 5V device. I know it says as much in the quote block, but it’s sort of misleading reading the schematic first, and then being told it’s wrong.