ad_2.c

Low End Microchip PICs C函数

// Program AD_2.C
//
// Illustrates the use of the A/D using interrupts.  Continually measures
// voltage on potentiometer on AN0 and displays A/D value and angle.
//
//
// copyright, Peter H. Anderson, Baltimore, MD, Dec, '00

#case

#device PIC16F877 *=16 ICD=TRUE

#include <defs_877.h>
#include <lcd_out.h> // LCD and delay routines

main()
{

   long ad_val;
   float angle;

   pcfg3 = 0; pcfg2 = 1; pcfg1 = 0; pcfg0 = 0;
   // config A/D for 3/0

   lcd_init();

   adfm = 1;   // right justified
   adcs1 = 1; adcs0 = 1; // internal RC

   adon=1;  // turn on the A/D
   chs2=0;  chs1=0;   chs0=0;
   delay_10us(10);   // brief delay to allow capture

   while(1)
   {
      adif = 0;      // kill any previous interrupt
      adie = 1;      // enable A/D interrupt
      peie = 1;      // enable peripherals
      gie = 1;
      adgo = 1;
#asm
      CLRWDT
      SLEEP
#endasm
      while(gie)      // be sure gie is off
      {
          gie = 0;   // turn of interrupts
      }
      ad_val = ADRESH;
      ad_val = ad_val << 8 | ADRESL;
      angle = (float) ad_val * 270.0 / 1024.0;
      lcd_clr_line(0);
      printf(lcd_char, "%ld", ad_val);
      lcd_clr_line(1);
      printf(lcd_char, "Angle = %2.1f", angle);
      delay_ms(3000);   // three second delay
   }
}

#int_ad ad_int_handler(void)
{
}

#int_default default_int_handler(void)
{
}

#include <lcd_out.c>