Thread: (Beginner) Nested C for PIC MCU - Problem displaying 0

Hello Everyone

(Please excuse if this is in a wrong section)

So I have strted my journey with C programming for PIC.
I got stuck when I want to display a 0 when counting down from 9 in a while loop

I have an array of numbers that I send to display ports of my MCU and when I count from 0 to 9 it is all good but not when counting down.

I think the problem is somewhere in here:

Code:

 if (digit<0) digit=9;

but I do not know how to correct it.

I want to display 0 and then start from 9 again.

Full code:

Code:

unsigned char const SEGMENT_MAP[10] = {0x3F,0x06,0x5B,0x4F,0x66,0x6D,0x7D,0x07,0x7F,0x6F};

void main(void) {
     TRISC = 0;                   //Set PortC to all outputs
     TRISBbits.RB6=1;             //Set Port B7 as an input
     OSCCON = 0X76;                  //SET fOR INTERNAL OSCCILATOR
     char digit=9;
     
  while(1){

      if (SW1)       //Check if switch SW1 is closed
      {
        for(int c=0; c<=20; c++)__delay_ms(5); //debouncing wait for 100ms
        
         if (SW1)       //Check if switch SW1 is still closed
         {
        PORTC = (SEGMENT_MAP[digit]);

   for (int count=0; count<20; count++) __delay_ms(50); //Delay 1 second
        
   digit--;
   if (digit<0) digit=9;
   
              }
      }
      else
      {
        PORTC = (SEGMENT_MAP[digit]);
      }
    }
}

Thank you all for your help and your expertise

char might be signed or unsigned (the result of digit-- is undefined behaviour if its value is 0)



The rest looks like you've been trying random changes hoping they might work... dunno... messy though

Changing

Code:

char digit = 9;

to

Code:

int digit = 9;

might work, but who knows

HODOR! HODOR! HODOR! HODOR!

It Works !!!! Such simple beginners things!
Massive thank you HODOR! As always you carry others to victory
Wasted almost 3 days myself on it!