Overview

A tri-colour LED can be either common anode (the longer pin is positive) or common anode (the longer pin is negative). The best way to identify which tri-colour LED you have is to set up a circuit to test it.

Pinout of a common cathode tri-colour LED

Pinout of a common anode tri-colour LED

PART 1: Identify the Tri-Colour LED

Checking common cathode

Connect the tri-colour LED as shown below. If the tri-colour LED lights up, then it is common cathode.

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Checking common anode

To confirm the tri-colour LED is common anode, connect it as shown below. The tri-colour LED should light up.

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PART 2: Use the Tri-Colour LED

Common cathode tri-colour LED

Connect a common cathode tri-colour LED as shown.

Here are examples of how you control the tri-colour LED using Arduino IDE and Scratch.