Toggle switch as momentary with debounce

Question

I have been trying to do the following: When a toggle switch is flipped down, the pic I'm using (16F1503) sends a pulse and turns on a led, when it is flipped up sends the same pulse and turns off the led. I managed to cobble some code together and works great. The problem is that I need to manage another toggle switch which it does exactly the same thing, but it sends a pulse on a different port and turns on/off a different led. Any suggestion? I'm having trouble mostly on debouncing multiple switches.

Here the code I'm using:

void main() 
{
uint8_t db_cnt;
PORTA=0;
PORTC=0;
ADCON0=0;
TRISA=0b001000;
TRISC=0b010000;


for(;;)
{
                //Wait for button press, debounce by counting:
                for (db_cnt=0; db_cnt <= 10; db_cnt++)
                {
                    __delay_ms(1);      //Sample every 1ms
                    if (TOGGLELEFT==0)  //If toggle off (RA3 low)
                        db_cnt=0;       //Restart count
                }                       //Until button on for 10 successive reads

                PORTA=0b100000;         //Turn OFF toggle LED, turn ON transistor
                __delay_ms(10);
                PORTA=0b000000;         //Turn OFF transistor

                //Wait for button release, debounce by counting:
                for (db_cnt=0; db_cnt <=10; db_cnt++)
                {
                    __delay_ms(1);      //Sample every 1ms
                    if (TOGGLELEFT==1)         //If toggle on (RA3 high)
                        db_cnt=0;       //Restart count 
                }                       //Until button off for 10 successive reads

                PORTA=0b110000;         //Turn ON toggle LED and transistor
                __delay_ms(10);
                PORTA=0b010000;         //Turn OFF transistor 
}
}

Answer 1

Your main problem in expanding this from one switch and one LED to two is that you need to keep track of the state of each pair separately but at the same time. So I would use two state machines, and two counters. Something like this:

state1 = 0;
state2 = 0;

while (1)
{
    switch(state1)
    {
       case 0:
           if (TOGGLELEFT==1)
               state1 = 1;      // go debounce next
               counter1 = 0;
           break;
       case 1:
           if (TOGGLELEFT==1)
               counter1++;
           else
               state1 = 0;      // start over
           if (counter1 > 10)   // after 10 ms,
           {
              PORTA=0b100000;   // turn OFF toggle LED, turn ON transistor
              state1 = 2;
           }
           break;
       case 2:
           counter1++;
           if (counter1 > 10)    // after 10 ms
           {
              PORTA=0b000000;    // turn OFF transistor
              state1 = 3;
           }
           break;
       case 3:
           if (TOGGLELEFT==0)
               state1 = 5;       // go debounce next
               counter1 = 0;
           break;
       case 3:
           if (TOGGLELEFT==0)
               counter1++;
           else
               state1 = 3;       // start over
           if (counter1 > 10)    // after 10 ms
           {
              PORTA=0b110000;    // turn ON toggle LED and transistor
              counter1 = 0;
              state1 = 5;
            }
           break;
       case 5:
           counter1++;
           if (counter1 > 10)     // after 10 ms,
           {
              PORTA=0b010000;    // turn OFF transistor
              state1 = 0;
           }
           break;
     }

     switch (state2)
     {
         // repeat with another switch statement for TOGGLERIGHT using state2 and counter2 etc.
     }

     __delay_ms(1);
}

So you can see how this allows you to keep track of both switches and LED's essentially in parallel.

I left the debounce timers the same as yours (10 ms) but I suggest making them considerably longer, say 50 ms.