Nuts and Volts - April 2014

Lab 3: Using a Pushbutton for Digital Control of an LED.

In Lab 1, we saw how to use a pushbutton to turn an LED on and off by making or breaking an analog circuit.

In this lab, we’ll see how to use the Arduino to read the pushbutton state and then decide whether to turn the LED on or off.

Parts required:

1 Arduino

1 Arduino proto shield

1 Pushbutton

1 1 KW resistor (brown/black/red)

1 LED

1 10 KW resistor (brown/black/orange)

5 Jumper wires

Pushbutton LED Circuit

[ASIDE: Figure 18 shows a photo of a physical realization of the circuit shown in Figures 16 and 17. Note that the jumper wires are not the same color as in the diagram, and that they obscure the view of the board. You’ll need to be extra careful when building the boards to make sure that you’ve connected the

Use a Pushbutton to Turn an LED On

Check off when complete:

; Make sure the power is off before building the circuit.

; Build the circuit shown in Figures 16 and 17.

; Plug the USB cable into the Arduino.

; Apply power to the circuit.

; Open the Arduino IDE and load the

C4_Pushbutton_LED program.

; Verify and upload the program to your Arduino.

// C4_Pushbutton_LED // Program turns LED on or off depending on // pushbutton state // Constants used to set pin numbers const int buttonPin = 12; // the number of the pushbutton pin const int ledPin = 11; // the number of the LED pin // variables int buttonState = 0; // variable the pushbutton status void setup() { // set the buttonPin mode to INPUT pinMode(buttonPin, INPUT); // set the ledPin mode to OUTPUT pinMode(ledPin, OUTPUT);