Program to blink external LED
Now that everything is connected, type the following program in Cloud9, save it as blinkExternalLED.js
and run. You should be able to see the LED blinking each second:
var b = require('bonescript'); var led = "P8_10"; var state = b.HIGH; var loopTime = 1000; var exitTime = 30000; b.pinMode(led, b.OUTPUT); b.digitalWrite(led, state); var loopTimer = setInterval(blink, loopTime); var exitTimer = setTimeout(exitProgram,exitTime); function blink() { if(state == b.LOW) state = b.HIGH; else state = b.LOW; b.digitalWrite(led, state); } function exitProgram() { b.digitalWrite(led,b.LOW); clearInterval(loopTimer); }
Explanation
This is the exact same program that we did in the previous chapter except we put LED as string P8_10
here. We declared P8_10
pin direction as output using function pinMode()
. When our program does digitalWrite()
HIGH
on P8_10
pin, the processor puts 3.3V on that pin. The current starts flowing from P8_10
to P8_2
and the LED glows...