Nelson MandEULA posted:

yospos please help. why is my code not working?

i want to turn on a pin (led for now, eventually dc motor via a TA7291P) when i push a button, and have it turn off after 15 seconds, or immediately if i push the button again. but it isn't working. idk why.

code:

unsigned long onTime;
const int BUTTON = 2;  // pushbutton 1 pin
const int LED =  13;    // LED pin
char on = 0;

void setup()
{
  onTime = millis();
  pinMode(LED, OUTPUT);
  pinMode(BUTTON, INPUT);
  
}

void loop()
{
   
  if (digitalRead(BUTTON) == LOW && on == 0)   // ON- STARTS TIMER
       {
         digitalWrite(LED, HIGH);  // LED comes On  
         onTime = millis();
	on = 1;
       }
  else if ((millis() - onTime > 15000 || digitalRead(BUTTON) == LOW) && on == 1)
       {
         digitalWrite(LED, LOW);
	on = 0;
       }
}

Sagebrush posted:

big lameoid sperg who doesn't wanna follow the arduino guidelines

Sagebrush posted:

bloody likes using char instead of boolean and 0|1 instead of true|false because he's a real life dev

Sagebrush posted:

bloody likes using char instead of boolean and 0|1 instead of true|false because he's a big lameoid sperg who doesn't wanna follow the arduino guidelines

bobbilljim posted:

Luigi Thirty posted:

reminds me I need to rewrite my C program to not be a spaghetti mess of interrupts and if statements

Bloody posted:

ive never used an ardweener so i dont wanna assume

Bloody posted:

lol if your C program is anything but this

Sagebrush posted:

try this

code:

unsigned long onTime;
const int BUTTON = 2;  // pushbutton 1 pin
const int LED =  13;    // LED pin
boolean active = false;


void setup()
{
  onTime = millis();
  pinMode(LED, OUTPUT);
  pinMode(BUTTON, INPUT);
  
}

void loop()
{

  if (digitalRead(BUTTON) == LOW) {   //if button is pressed
    if (active) {                     //and the light is already on,
      active = false;                 //set status to off
    }    
    else {                            //if the light is not already on
     active = true;                   //set status to on
     onTime = millis();               //and initialize the timer
    }
    delay(200);                       //this is here to debounce the button
  }

  if (millis() > onTime + 15000) {    //if 15 seconds have elapsed since the last time the led went on
    active = false;		      //set status to off
  } 

  if (active) {                       //if status is on
    digitalWrite(LED, HIGH);          //turn led on
  }
  else {                              //otherwise
    digitalWrite(LED, LOW);           //turn led off
  }

}
	

i like breaking things up into logical blocks executed in order instead of one big conditional

Sagebrush posted:

an extra component costs less than a line of code?

Doc Block posted:

the arduino language is C++, not C, so bools are a real thing. as is const, which in C++ is a typesafe equivalent of #define

getting to the source of your problem, and ignoring the debouncing issues that others have already solved, you say that your button is wired up using a pull-down resistor, yet in your code you are checking to see if the pin is LOW. problem is, the pull-down resistor means the pin will be LOW when the button isn't being pressed, and will be HIGH when it is pressed.

another problem is that with arduinos (and any ATmega microcontrollers) that external pull-down resistor is unneeded. the ATmega328 has internal pull-up resistors on all pins capable of being used as input, so just use those unless you really really need that pin to be pulled low when unpressed instead of being pulled high.

to enable the internal pull-up resistor for a pin, using the arduino library you just do

C++ code:

pinMode(your_pin, INPUT_HIGH);

then the pin will be LOW when the button is pressed and HIGH when it isn't.

Doc Block posted:

actually, what you should do is forego the busy loop and just set the pin up to fire an interrupt when its pulled to the desired level, and the interrupt handler sets up a timer interrupt that goes off after 15 seconds, and the rest of the time keep the microcontroller in the lowest power mode possible that still keeps the timers and pin change sensing enabled.

edit: and an extra component is way more complicated and expensive than even many extra lines of code.

Doc Block posted:

except that the extra component takes up space on the PCB, affects your design, adds complexity to manufacturing, and the capacitor itself adds to the unit's cost.

edit: and if I remember my low-level ATmega poo poo correctly, when going from low power mode to full power mode after a pin change interrupt, the microcontroller can't respond to another pin change interrupt for X number of milliseconds, taking care of your debouncing for you. IIRC.

Bloody posted:

doc block: mad about caps

graph posted:

shut up nerds

Balls-kun posted: