main.c

摩托罗拉08单片机AD转换程序 使用CodeWarrior开发

/**
 * Copyright (c) 2004, Freescale Semiconductor
 * Freescale Willy Note
 *
 * File name   : main.c
 * Project name: HC08 ADC Willy Note
 *
 * Author      : Luis Reynoso
 * Department  : RTAC Americas
 *
 * Description : This is a descriptive example of the ADC module in the 
 *               MC98HC908QY4 MCU.
 *               The Example will turn on a LED when PTA5/OSC1/AD3 is 
 *               greater than 2.5V.
 *
 * History     :
 * 29/06/2004  : Release. (A19257)
 */

#include <hidef.h>          /* for EnableInterrupts macro */
#include <MC68HC908QY4.h>   /* include peripheral declarations */

/* Macro Definitions */
#define START_CONVERSION(Channel)	ADSCR = 0x40|(Channel);		
                                    /*  
                                     *  0b010XXXXX
                                     *	  ||||||||__ 
                                     *	  |||||||___| 
                                     *	  ||||||____|-->  Selected Channel
                                     *	  |||||_____|
                                     *	  ||||______| 
                                     *	  |||_______ Single ADC conversion
                                     *	  ||________ ADC interrupt Enabled
                                     *	  |_________ Unimplemented
                                     */  
/* Functions prototypes */
void MCUInit (void);
void ADCInit (void);

/* Global Variables */
volatile unsigned char result;  /* Result of the ADC conversion */

void main(void) {

    MCUInit();
    DDRA = 0x02;             /* Set PTA1 as output */
    ADCInit(); 
    EnableInterrupts;
    START_CONVERSION(0x03);	 /* 
                              * Start Conversion for Ch3 (See #define)
                              * Since Internal OSC is used, AD3 is free
                              */
    for(;;) 
        ; /* Empty Body */
}

/*
 * ADCIsr: Interrupt Service routine for the ADC.
 * It will turn on PTA1 if ADC result is greater than 128(2.5V).
 *
 * Parameters: None
 *
 * Return : None
 */
void interrupt 16 ADCIsr (void){

    result = ADR;               /* Read result and acknowledge interrupt */
    PTA_PTA1 = (result >> 7);   /* Turn on PTA1 if result > 128 */
    START_CONVERSION(0x03);     /* Re-Start Conversion for Ch3 */

    return;
}

/*
 * ADCInit: Initialization of the ADC Module.
 * For the QY4 it will configure the ADC clock.
 *
 * Parameters: None
 *
 * Return : None
 */
void ADCInit (void)
{

    ADICLK = 0x40;          /*  
                             *  0b01000000
                             *    ||||||||__ 
                             *	  |||||||___| 
                             *	  ||||||____|
                             *	  |||||_____|--> Unimplemented 
                             *	  ||||______| 
                             *	  |||_______| 
                             *	  ||________\__	ADC Clock Rate = BusClock/4 
                             *	  |_________/ 
                             *   ADC Clock Rate = BusClock/4 = 3.2Mhz/4 =0.8Mhz
                             *  The ADC clock frequency should be set between 
                             *  fADIC(MIN) = 0.5Mhz and fADIC(MAX) = 1.048Mhz
                             */
    return;
}

/*
 * MCUInit: Initialization of the MCU.
 * It will configure the QY4 to use the internal oscillator.
 *
 * Parameters: None
 *
 * Return : None
 */
void MCUInit (void)
{

    CONFIG1 = 0x39;         /*  
                             *  0b00111001
                             *    ||||||||__ COP Module Disabled
                             *	  |||||||___ STOP is illegal
                             *	  ||||||____ Stop recovery after 4096 cycles
                             *	  |||||_____ LVI operate in 5-V mode
                             *	  ||||______ LVI module disabled
                             *	  |||_______ LVI resets disabled
                             *	  ||________ LVI disabled in stop mode
                             *	  |_________ COP reset long cycle
                             */
    CONFIG2 = 0x01;	        /*  
                             *  0b00000001
                             *	  ||||||||__ Reset function active in pin
                             *	  |||||||___ Reserved
                             *	  ||||||____ Reserved
                             *	  |||||____
                             *	  ||||_____> Internal Oscilator
                             *	  |||_______ Reserved
                             *	  ||________ IRQ inactive in pin
                             *	  |_________ IRQ pullup connected
                             */  
    OSCTRIM = 0x75;         /* Trim OSC with value in Flash (0xFFC0) */

    return;
}