Spiff's Electronics Notebook

With the aforementioned knowledge, the final version of the C code for the counting PIC program is below, it is now functionally identical to the JAL version previously posted. The compiler creates an astonishly small 75 words/instructions of program code from this and uses only 6 bytes of RAM (or file registers for the Microchip inclined).

#include        <pic.h>

#define        PORTBIT(adr, bit)        ((unsigned)(&adr)*8+(bit))

static bit hl @ PORTBIT (PORTA, 2);

main (void)

{
   unsigned char i,
                 j,
                 k;
   char ud = 0;
   char high_low;

   CMCON = 0x07;                /* disable analog functions on PORTA */

   TRISB = 0;                        /* all bits output */
   TRISA = 0 b00000100;                /* 3rd bit as input all others output */
   j = 0;
   for (;;) {
      high_low = hl;
      if (high_low)
         PORTB = j;
      for (i = 255; --i;)
         for (k = 64; --k;) {
            if ((k & 0 b111) == 0 b111) {        /* LEDs on */

               if (!high_low)
                  PORTB = j;
               PORTA = (ud) | (((!ud) << 1) & 0 b10);
            } else {                /* LEDs off */
               if (!high_low)
                  PORTB = 0;
               PORTA = 0;
            }
         }
      if (j == 0)
         ud = 1;
      if (j == 0xFF)
         ud = 0;
      if (ud)
         j++;
      else
         j--;
   }
}

It should also be mentioned, that PICC Lite doesn't know about the 16f628 and treats in like it's smaller sibling, the 16f627. So, if you're using PICC Lite and you want to use a 16f62x class chip, you might as well save some cash and buy 16f627 chips.