using one button to change states

Basically what I'm trying to do with this C code is to mimic a momentary push button to turn on an led on and off.

Initially the LED will be OFF.

When LED is OFF and button is pressed the LED turns ON.
When LED is ON and button is pressed the LED turns OFF.

That's all I'm trying to do, one press on, one press off.
So I have the below code, but was wondering what other approaches others would use or if there is a simpler way of doing what I'm trying to accomplish. The below code is not working 100% either, I'm missing something.

Code:

#include <stdio.h>
#include <stdlib.h>
#include <ctype.h>
#include <windows.h>

int main (void)
{

	int BTNpress = 0; //To mimic press of button, a 1 = button has been pressed.
	int LEDStat = 0;  //LED is initialy off(0)

while (TRUE) //loop to scan the button state
{
	 puts( "Enter 1 to press the button");
     scanf( "%d", &BTNpress); 

	 if (BTNpress  && !LEDStat) //if button is pressed and the LED is OFF then turn LED ON
	 {
		 printf("The button has been pressed\n"); 
		 printf("LED is ON\n");
		 LEDStat = 1; //Change LEDStat to 1 to inidica the LED is ON.
	 }

	 puts( "Enter 1 to press the button");
     scanf( "%d", &BTNpress); 

	 if (BTNpress && LEDStat)	//if button is pressed and the led is ON then turn LED OFF
	 {
		 printf("The button has been pressed\n"); 
		 printf("LED is OFF\n");
		 LEDStat = 0; //Change LEDStat to 0 to inidica the LED is OFF.

	  }
	 }

system("PAUSE");
return 0;
}

The below code is not working 100% either

Don't keep us in suspense, what's not working about it?

You don't need the second copy of

Code:

    puts( "Enter 1 to press the button");
    scanf( "%d", &BTNpress); 
...

Just have the user input once, and test for the LED state and essentially, toggle it. In fact, I'd make a function called ToggleLED and call it each time the "button" is pressed.

Like this...

Code:

while (1)
 {/wait for button press
 if (ledoff)
   turn led on
   ledoff = false
 else
   turn led off
   ledoff = true
}

Ok, this is what I'm down to now.

Code:

#include <stdio.h>
#include <stdlib.h>
#include <ctype.h>
#include <windows.h>

int main (void)
{

	int BTNpress = 0; //To mimic press of button, a 1 = button has been pressed.
	int LEDStat = 0;  //LED is initialy off(0)

while (TRUE) //loop to scan the button state
{
	 puts( "Enter 1 to press the button");
     scanf( "%d", &BTNpress); 

	 if (BTNpress  && !LEDStat) //if button is pressed and the LED is OFF then turn LED ON
	 {
		 //printf("The button has been pressed\n"); 
		 printf("LED is ON\n");
		 LEDStat = 1; //Change LEDStat to 1 to indicate the LED is ON.
	 }

	 else if (BTNpress && LEDStat)	//if button is pressed and the led is ON then turn LED OFF
	 {
		//printf("The button has been pressed\n"); 
		 printf("LED is OFF\n");
		 LEDStat = 0; //Change LEDStat to 0 to inidica the LED is OFF.

	  }		
	 }

system("PAUSE");
return 0;
}

Now I want to add debounce to it.

You are still overcoding....

Code:

#include <stdio.h>
#include <stdlib.h>
#include <ctype.h>
#include <windows.h>

int main (void)
{

	int BTNpress = 0; //To mimic press of button, a 1 = button has been pressed.
	int LEDStat = 0;  //LED is initialy off(0)

while (TRUE) //loop to scan the button state
{
     puts( "Press Enter to press the button");
     getchar();                 <--- it's going to sit here until you push the button, it's not going anywhere

     if (BTNpress  && !LEDStat)  <--- bold faced text is unnecessary
      { //printf("The button has been pressed\n"); 
        printf("LED is ON\n");
        LEDStat = 1;  }
       else if (BTNpress && LEDStat)   <---- since there are only two posible states this is unnecessary		 {
          {  //printf("The button has been pressed\n"); 
           printf("LED is OFF\n");
           LEDStat = 0;  }		
 }

system("PAUSE");
return 0;
}

Leaving you with.....

Code:

#include <stdio.h>
#include <stdlib.h>
#include <ctype.h>
#include <windows.h>

int main (void)
{  int LEDStat = 0;  //LED is initialy off(0)

while (TRUE) //loop to scan the button state
{
     puts( "Press Enter to press the button");
     getchar(); 

     if (!LEDStat)  
      {  printf("LED is ON\n");
         LEDStat = 1;  }
     else 
      {  printf("LED is OFF\n");
         LEDStat = 0;  }		
 }

system("PAUSE");
return 0;

thanks for you explanation and making my mess cleaner.
I have no idea where the bold stuff came from, but ok.

Originally Posted by CommonTater

Like this...

Code:

while (1)
 {/wait for button press
 if (ledoff)
   turn led on
   ledoff = false
 else
   turn led off
   ledoff = true
}

You can also just use a single statement:

Code:

ledstate = ! ledstate;

Quzah.

Originally Posted by drkidd22

thanks for you explanation and making my mess cleaner.
I have no idea where the bold stuff came from, but ok.

I put it in there to show you what you didn't need....

Originally Posted by CommonTater

I put it in there to show you what you didn't need....

Bold or in color, people just can't understand simple highlighting.


Quzah.

Originally Posted by quzah

Bold or in color, people just can't understand simple highlighting.
Quzah.

What? I thought it was perfectly obvious.

Originally Posted by CommonTater

What? I thought it was perfectly obvious.

Don't get me started! I had a program (I still have it here some place) that would color every character on a gradient, or random colors.

Quzah.