ARDUINO
PROJECT – RGB LED

PROJECT DESCRIPTION

You will connect your Arduino to an RGB LED.

LESSONS

You should look up the RGB LED page in the Electronics unit if you haven’t.

WARNING: The longest pin on an RGB LED is a common pin that connects to all three individual LEDs. It needs to be connected to a resistor.

STEPS

1-Determine if your RGB LED is a Common Anode (+) or Common Cathode (-) LED. You can

To test if it is Common Anode, connect the longest pin to a resistor and the resistor to 5V. Then connect any other pin to Ground to see if one of the LEDs goes on.

To test if it is Common Cathode, connect the longest pin to a resistor and the resistor to GROUND. Then connect any other pin to 5V to see if one of the LEDs goes on.

If neither of the above tests work, see your teacher.

2-Connect your LED to your Arduino.

No matter the result from Step 1, the connection for the longest pin stays as is. You need to disconnect any of the other LED pins that you might have connected for testing purposes.

Each pin should now be connected to a digital pin on the Arduino. I suggest red to pin 3, green to pin 5 and blue to pin 6 since those pins are PWM pins (they have a ~ symbol on them).

Note: If your LED is Common Anode, your pins actually have to output ZERO to turn on the LEDs. If your LED is Common Cathode, your pins need to output ONE.

3-Write the following program:

• It has three global variables named rpin, gpin and bpin that are set to the values 3, 5 and 6 (to represent the pin numbers).
• In the setup method, make sure to set all three pins to OUTPUT using the pinMode() command.
• Still in the setup method, try using analogWrite (rpin, 0) and then analogWrite(rpin, 255) to see which one turns on the LED.

4-Test your program. Your LED should show red.

5-You should now explore with different values for all three pins. Note that the colour of your LED will not exactly match true RGB colours (in part because the red LED should have a different resistor than the green and blue ones as it is rated for a lower voltage).

6-Make sure you can create a few common colours such as pink, yellow, orange, lime green, purple, light blue, teal, and so on…

PROJECT EXPECTATIONS

Mr. Campeau will ask you to show him a specific colour on the LED and you must do so within 1 minute.