lab3_solution.c

另一个MICROCHIP的18F系列单片机的一个DEMO程序

#include <delays.h>

#pragma romdata CONFIG
_CONFIG_DECL (_OSC_HS_1H & _OSCS_OFF_1H, _PWRT_OFF_2L & _BOR_OFF_2L, _WDT_OFF_2H, _CONFIG3L_DEFAULT, _CCP2MUX_OFF_3H, _LVP_OFF_4L, _CONFIG5L_DEFAULT, _CONFIG5H_DEFAULT, _CONFIG6L_DEFAULT, _CONFIG6H_DEFAULT, 0xFF, _CONFIG7H_DEFAULT);

#pragma romdata
void tmr2 (void);
void button (void);

#pragma code high_vector_section=0x8
void
high_vector (void)
{
_asm GOTO button _endasm
}

#pragma code

#pragma code low_vector_section=0x18
void
low_vector (void)
{
_asm GOTO tmr2 _endasm}

#pragma code
volatile unsigned s_cur_ad_val;
int count = 0;
volatile enum
{ DIR_LEFT = 0, DIR_RIGHT } direction;

#pragma interruptlow tmr2
void
tmr2 (void)
{
  /* clear the timer interrupt flag */
  PIR1bits.TMR2IF = 0;

  /* if we've reached the repeat count, update the LEDs */
  if (count++ < s_cur_ad_val)
    return;
  else
    count = 0;
  if (direction == DIR_LEFT)

    {
    _asm rlncf PORTD, 1, 0 _endasm
    }
  else
    {
    _asm rrncf PORTD, 1, 0 _endasm
    }
}

#pragma interrupt button
void
button (void)
{
  direction = !direction;

  /* store the new direction in EEDATA. Note that since we're already
     in the high priority interrupt, we don't need to explicitly
     enable/disable interrupts around the write cycle */
  EEADR = 0;
  EEDATA = direction;
  EECON2 = 0x55;
  EECON2 = 0xaa;
  EECON1bits.WR = 1;
  while (!PIR2bits.EEIF)
    ;
  PIR2bits.EEIF = 0;

  /* clear the interrupt flag */
  INTCONbits.INT0IF = 0;
}

void
main (void)
{

  /* The first thing to do is to read read the start direction from
     data EEPROM. */
  EEADR = 0;
  EECON1bits.EEPGD = 0;         /* point to EEDATA */
  EECON1bits.WREN = 1;          /* enable EEDATA writes */
  EECON1bits.RD = 1;
  direction = EEDATA;

  /* Make all bits on the Port D output bits for the LEDs */
  TRISD = 0;

  /* Make PORTA RA0 input, for the A/D converter */
  TRISAbits.TRISA0 = 1;

  /* PORTB RB0 input for the button */
  TRISBbits.TRISB0 = 1;

  /* Reset Port D. Set just one bit to on. */
  PORTD = 1;

  /* Enable interrupt priority */
  RCONbits.IPEN = 1;

  /* clear the peripheral interrupt flags */
  PIR1 = 0;

  /* enable the timer interrupt */
  PIE1bits.TMR2IE = 1;
  IPR1bits.TMR2IP = 0;

  /* Set the button on RB0 to trigger an interrupt. it's always high
     priority */
  INTCONbits.INT0IE = 1;

  /* configure the ADC, most of this is the default settings: Fosc/32
     AN0 Analog, AN1-15 Digital Channel zero Interrupt disabled
     Internal voltage references An equivalent setup using the ADC
     library would be: 
     OpenADC (ADC_FOSC_32 & ADC_LEFT_JUST & ADC_1ANA,
              ADC_CH0 & ADC_INT_OFF & ADC_VREFPLUS_VDD & ADC_VREFMINUS_VSS );
    */
  /* FOSC/32 clock select */
  ADCON2bits.ADCS0 = 1;
  ADCON2bits.ADCS1 = 1;
  ADCON2bits.ADCS2 = 1;
  ADCON2bits.ADCS2 = 1;

  /* AN0-15, VREF */
  ADCON1 = 0b00001110;

  /* enable interrupts */
  INTCONbits.GIEH = 1;
  INTCONbits.GIEL = 1;

  /* turn on the ADC */
  ADCON0bits.ADON = 1;

  /* enable the timer */
  T2CONbits.TMR2ON = 1;

  /* start the ADC conversion */
  while (1)
    {
      /* Give the ADC time to get ready. */
      Delay100TCYx (2);

      /* start the ADC conversion */
      ADCON0bits.GO = 1;
      while (ADCON0bits.GO) ;
      s_cur_ad_val = ADRES;
    }
}