Blink on Command

Part of the Inputs section of Coddy's Arduino journey. Lesson 18 of 22.

Type 3 and the LED should blink three times, then stop. loop() already repeats, so let it do the counting: keep a variable with the number of blinks still to do. Each time loop() runs, if there are blinks left, blink once and take one away.

int blinksLeft = 0;

void loop() {
  // a number from the Serial monitor sets blinksLeft
  if (blinksLeft > 0) {
    // one blink
    blinksLeft = blinksLeft - 1;
  }
}

When blinksLeft reaches 0, the if is false and the LED stays dark until the next number.

The newline after the number still makes parseInt() return 0 a second later. Ignore the 0 as before, or it would wipe out the blinks still to do.

Challenge

Medium

Blink the LED on pin 13 as many times as the number typed into the Serial monitor:

when characters are waiting, read a number with parseInt(), and store it in blinksLeft if it is above 0
if blinksLeft is above 0, blink once (200 ms on, 200 ms off) and take one away

Press Run, send 3 from the Serial monitor, then Check.

Try it yourself

const int ledPin = 13;

int blinksLeft = 0;

void setup() {
  pinMode(ledPin, OUTPUT);
  Serial.begin(9600);
}

void loop() {
  // a number from the Serial monitor sets blinksLeft
  // while blinksLeft is above 0, blink once and take one away
}

Test yourself

This lesson includes a short quiz. Start the lesson to answer it and track your progress.

All lessons in Inputs

Practice on your own: Arduino playground