In this tutorial we will show you how to use the UNO R3 PLUS to drive a 7 segment LED display. We will show you how to wire up the LED display, and show a simple count down example from 9 to 0.
I – Stuffs that you will need:
You will need a UNO R3 Plus board, a mini USB to standard USB cable, a PC as well as a breadboard, 7 segment LED, resistors and jumper cables for assembling the circuit.
UNO R3 Plus Mini USB to Standard USB Windows PC
Breadboard 7 Segment LED Display 7x330ohm Resistors
Jumper cables 2N3904 NPN transistor
II – Background Information:
We will be using a two digit 7-segment LED for this tutorial, but we will only be exercising the right digit. This LED is a command anode device. We will apply a 5V to pin 13. To light up the LED segment, we will need to pull the cathode (or the negative) side to ground via a 330 ohm resistor. To turn off the LED segment, we will pull the cathode side to 5V via a 330 ohm resistor. We will use the UNO R3 Plus digital output pins to drive these LED segments, we will need 7 pins to drive 7 segment.
III – Wiring the Breadboard:
Let’s wire up the bread board. We will map the digital pin as following:
- Digital pin 2: segment a
- Digital pin 3: segment b
- Digital pin 4: segment c
- Digital pin 5: segment d
- Digital pin 6: segment e
- Digital pin 7: segment f
- Digital pin 8: segment g
IV – Writing the Sketch:
Start a new project and copy and paste the below sketches into the Arduino environment. This sketch setups digital pin 2 to 8 as output, and setup a lookup table that would display a value of 0 to 9. Once the sketch is loaded on the board, you will see the number decrement from 0 to 9 continuously.
CLICK TO DOWNLOAD ALL TUTORIAL CODES: ARD101_Tutorial_Code
Things we have covered in this tutorial:
- Using 7-segment LED display
Tutorial 8: Powering the UNO R3 PLUS Using Batteries