picdem2.c

pic单片机例程

/* This is a simple demo project written for use with
 * the HI-TECH Software PICC compiler. It may be compiled
 * and run on the Microchip PICDEM 2 PLUS DEMO BOARD.
 * Features demonstrated include driving the LCD display and
 * the A2D converter. 
 
 Additional files required for this demo are included in the
 PIC\SAMPLES directories:
 DELAY\delay.c
 DELAY\delay.h
 lcd.c
 lcd.h
 */

#include <htc.h>
#include <stdio.h>
#include "lcd.h"

/* this is the maximum value of an A2D conversion. */
#define MAXVOLTAGE 5

void init(void){
	lcd_init(FOURBIT_MODE);
	ADON=1;	/* enable A2D converter */
	ADIE=0;	/* not interrupt driven */
	ADCON1=0x0E;
	ADCON0=1;
	TRISB=0x00;	// Set PORTB in output mode
	T1CON=0x31;	// turn on timer 1
	TMR1IE=1;	// timer 1 is interrupt enabled
	PEIE=1;		// enable peripheral interrupts
	GIE=1;		// turn on interrupts
}

void interrupt isr(void){
	if(TMR1IE && TMR1IF){
		PORTB++;
		TMR1IF=0;
	}
}

void main(void){
	unsigned char last_value;
	unsigned char volts;
	unsigned char decivolts;
	unsigned char outString[20];

	init();
	lcd_puts("Adust the");
	lcd_home2();	// select line 2
	lcd_puts("potentiometer");	

	while(1){
		ADGO=1;
		while(ADGO)continue;
		ADIF=0;
		if(ADRESH!=last_value)
		{
			volts=0;
			for(decivolts=(ADRESH*10*MAXVOLTAGE/255);decivolts>=10;decivolts-=10)
				volts++;
			lcd_clear();
			sprintf(outString,"A2D = %d.%d volts",volts,decivolts);
			lcd_puts(outString);
		}
		last_value=ADRESH;
	}
}