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I am trying to work with arduino timer1 interrupts to make an led blink every bit on an 8 bit number, depending on whether its a 1 or 0. However, im trying to make a basic blinking program, and it does not seem to be working.

#include “TimerOne.h”
bool val=0;
void setup()
{
    pinMode(13, OUTPUT);
    Timer1.initialize(500000); // initialize timer1, and set a 1/2 second period
    Timer1.attachInterrupt(callback); // attaches callback() as a timer overflow interrupt
}

void callback()
{
    val=1;
}

void loop()
{
    digitalWrite(13,val);
    while(!val);
    val=0;
}

The LED doesnt blink at all! Any help would be appreceitated! thanks!

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2 Answers 2

Reset to default
1

Try this instead.

#include “TimerOne.h”
bool val=0;
void setup()
{
    pinMode(13, OUTPUT);
    Timer1.initialize(500000); // initialize timer1, and set a 1/2 second period
    Timer1.attachInterrupt(callback); // attaches callback() as a timer overflow interrupt
}

void callback()
{
    val=!val;
}

void loop()
{
    digitalWrite(13,val);
}
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0

I'm not surprised the LED doesn't blink - the entirety of your logic in the loop() function is so bizarre as to elicit the question:

WTF?

Let's take a look at it line by line:

digitalWrite(13,val);

Set the LED to whatever val is - val starts as 0, so the LED is off.

while(!val);

While val is not anything except 0, so while val is zero, do nothing. (The interrupt would escape you from this if your val was volatile)

val=0;

Set val to 0.

So how can val be anything except 0 when you do the digitalWrite?

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