//          mod10a.c      RGD 1/4/03
//  This is a simple test program for module 10 (ME499)

#include <16f84a.H>
// This tells the compiler that we will use a 4 MHz crystal
#fuses HS, WDT, NOPROTECT     
// This sets up the internal device fuses: HS crystal, WDT ON, Code Protect OFF
#use delay (clock=4000000)   
#byte PORTA = 5
#byte PORTB = 6

unsigned int x;

///////////////////////////////////////
// SUBROUTINES

void init_ports(void) {
   SET_TRIS_A(0b11111111);  // PORTA = all outputs
   SET_TRIS_B(0b00000000);  // PORTB = all inputs
//  set Watch Dog Timer prescaler to 1152 ms:   
   SETUP_COUNTERS(RTCC_INTERNAL, WDT_1152MS);  
// Default output values:
   PORTB = 0b00000000;   //  turn off all LEDs
// Default variable values
   x = 0b00000000;
}

//////////////////////////////////////
// PIC16F84a microcontroller goes here at RESET

void main() {
      init_ports();  // Initialize ports
      restart_wdt(); // Reset the WDT

 CYCLE:  // Run continuously
   x = input_a();    // read (input) all of the bits from port A into the variable x
      //NOTE: Port A only has five I/O pins, the remaining 3 bits are always = 0

   if(x == 0b00000000) OUTPUT_B(0b00000000);
      // No buttons are pressed, so turn off all LEDs
      // note also the use of == as opposed to a single =
      // two == signs means "are the two values equal?"
      // a single = sign means "set the left variable to equal the value on the right"
      
   if(x == 0b00000001) OUTPUT_B(0b00000001);
      // Only SW1 was pressed, so turn ON the LED connected to RB0
      
   if(x == 0b00000010) OUTPUT_B(0b00000010);
      // Only SW2 was pressed, so turn on the LED connected to RB1
      
   while(x == 0b00000011) {  // if both SW1 and SW2 are being pressed...
     OUTPUT_B(0b11111111);   // turn ON all LEDs
     delay_ms(250);          // wait for 1/4 of a second
     OUTPUT_B(0b00000000);   // turn OFF all LEDs
     delay_ms(250);          // wait for 1/4 of a second
     // NOTE: the above 4 lines will cause all of the LEDs to flash 
     // for as long as both SW1 and SW2 remain pressed
     restart_wdt();
     x = input_a();    // check to be sure both SW1 and SW2 are still pressed
   }  // this is the end of the WHILE loop
      
 goto CYCLE;  // go back and infinitely loop to the label CYCLE

} // main…this is the end of the program