Page 99 - Programming the Photon Getting Started With the Internet of Things

Figure 5.3 Breadboard layout diagram for connecting a push button.

Here is our basic digital input sketch, which will use the push button as the input
device and light up the on-board LED, which is connected to digital pin 7 as an output:

int pushbutton = D0;

int led = D7;

void setup() {
pinMode(pushbutton, INPUT);

pinMode(led, OUTPUT);
}

void loop() {

int buttonstate = digitalRead(pushbutton);
if (buttonstate == HIGH){
digitalWrite(led, HIGH);