Freenove Ultimate Starter Kit, Manual

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Chapter 2 Button & LED
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}
}
return 0 ;
}
In the circuit connection, LED and Button are connected with GPIO17 and GPIO18 respectively, which
correspond to 0 and 1 respectively in wiringPI. So define ledPin and buttonPin as 0 and 1 respectively.
#define ledPin 0 //define the ledPin
#define buttonPin 1 //define the buttonPin
In the while cycle of main function, use digitalRead(buttonPin) to determine the state of Button. When the
button is pressed, the function returns low level, the result of “if” is true, and then turn on LED. Or, turn off
LED.
if ( digitalRead ( buttonPin ) == LOW ){ //button has pressed down
digitalWrite ( ledPin , HIGH ); //led on
printf ( "led on...\n" );
}
else { //button has released
digitalWrite ( ledPin , LOW ); //led off
printf ( "...led off\n" );
}
About digitalRead():
i n t digitalRead (int pin) ;
This function returns the value read at the given pin. It will be “ HIGH ” or “ LOW ”(1 or 0) depending on the
logic level at the pin.