Button reading not going off

Question

I made a circuit which in my intentions would allow me to toggle a LED dimming loop.

Problem is that once I push the button the first time pushing it a second time doesn't toggle the LED loop off.

Here is the code:

const int LED = 9; // the pin for the LED
const int BUTTON = 7;
int val = LOW;
int old_val = LOW;
int state = 0;
int i = 0;
void setup()
{
 pinMode(LED, OUTPUT);
 pinMode(BUTTON, INPUT);
}
void loop()
{
 val = digitalRead(BUTTON);
 if ((val == HIGH) && (old_val==LOW))
 {
 state = 1 - state;
 delay(10);
 }
 old_val = val;
 if (state == 1)
 {
 for (i = 0; i < 255; i++) // loop from 0 to 254 (fade in)
 {
 analogWrite(LED, i); // set the LED brightness
 delay(10); // Wait 10ms because analogWrite
 // is instantaneous and we would
 // not see any change
 }
 for (i = 255; i > 0; i--) // loop from 255 to 1 (fade out)
 { 
 analogWrite(LED, i); // set the LED brightness
 delay(10); // Wait 10ms 
 }
 } else
 {
 analogWrite(LED, 0);
 }
 if ((val == LOW) && (old_val == HIGH)) 
 {
 delay(10);
 }
}

Here is the circuit scheme:

circuit schematics

I would be interested both in learning what the problem is AND learning any mental methods I can apply to debug in such situations.

• Ignacio Vazquez-Abrams: Is the 10kohm resistor really connected to A5, A4, A3, A2, A1, A0, VIN, and GND?
• Fabrizio Bianchi: No, only to GND1. It is a problem with the rendering in 123d circuits.
• Ignacio Vazquez-Abrams: Then you should consider fixing your wiring diagram.
• Fabrizio Bianchi: There! I fixed it.
• Gerben: While the led is fading in and out (which takes 5 seconds), the state of the button is never checked. So you'd need to have the button released for at least 5 seconds (so old_val becomes LOW), and then pressed exactly we the led is faded out (again, 5 seconds later). So try keeping the button pressed for at least 5 seconds. PS you probably want to rewrite your code, so the button is more 'responsive'.

Answer 1

While the led is fading in and out (which takes 5 seconds), the state of the button is never checked. So you'd need to have the button released for at least 5 seconds (so old_val becomes LOW), and then pressed exactly we the led is faded out (again, 5 seconds later). So try keeping the button pressed for at least 5 seconds.

You probably want to rewrite your code, so the button is more 'responsive'. Below I added an example of how to do this.

const int LED = 9; // the pin for the LED
const int BUTTON = 7;
int val = LOW;
int old_val = LOW;
bool fadeLed = false;
int brightness = 0;//current pwm value
int direction = 1;// 1 is brightness is increasing, -1 if brightness is decreasing 
void setup()
{
 pinMode(LED, OUTPUT);
 pinMode(BUTTON, INPUT);
}
void loop()
{
 /* check the button */
 val = digitalRead(BUTTON);
 if ((val == HIGH) && (old_val==LOW))
 {
 // button pressed ( called only once per press )
 fadeLed = !fadeLed;// invert boolean
 }
 old_val = val;
 /* update the leds brightness */
 if( fadeLed )
 {
 // fade led in and out
 if( brightness==0 )
 direction = 1;//change direction is minimum value reached
 if( brightness==255 )
 direction = -1;//change direction is maximum value reached
 brightness += direction;// increase/decrease brightness
 }
 else
 {
 // fadeLed is disabled, so only decrease brightness till it reaches zero
 if( brightness>0 )
 brightness--;
 }
 analogWrite(LED, brightness); // set the LED brightness
 delay(10); // Wait 10ms because analogWrite
 // is instantaneous and we would
 // not see any change
}

Any questions about the code; just let me know.