External Interrupt

The onboard USR button connects to P6 (GPIO37/EINT20). To use this button as an input, you can either poll the pin state with digitalRead, or use the EINT APIs in Arduino.

With Digital Read

1. Change the LED pin from 13 to 7, for example:

   const int ledPin = 7; // the number of the LED pin

2. Change the button pin from 2 to 6, for example:

   const int buttonPin = 6; // the number of the pushbutton pin

Now upload the sketch to the board. The onboard USR LED should light up when the USR button is pressed.

With EINT API

Arduino provides APIs to handle EINT(external interrupts), and only 4 pins on LinkIt 7697 support EINT function. As an example, you'll learn how to use USR button (P6/GPIO37/EINT20) with the EINT API.

Open Arduino IDE and copy the following code to the editor:

#include "Arduino.h" 
 
const int led = 7; // USR LED pin is P7 
const int usr_btn = 6; // USR BTN pin is P6 
int val = 0; // Variable that stores LED state. 
 
void pin_change(void) 
{ 
    digitalWrite(led, val); 
    val = !val; 
    Serial.println("button pressed"); 
} 
 
void setup() { 
    pinMode(led, OUTPUT); 
    attachInterrupt(usr_btn, pin_change, RISING); 
    Serial.begin(9600); 
} 
 
void loop() { 
    delay(1000); 
}

In the example code above, when the button is pressed (RISING edge), the pin_change callback will be invoked. In the function, you change the state of the LED. After uploading this sketch to the board, press the USR button to turn on the USR LED, and press again to turn it off.

Note that only P1, P2, P3 and P6 support the attachInterrupt API.