demo_8_4.i

这是马潮老师最新力做<<AVR单片机潜入式系统原理与应用实践>>中有关数码管显示时间的C程序,用CVAVR编译,对想熟悉和学习AVR单片机的朋友一定有用.注释详细,一看就懂.

/*********************************************
File name		    : demo_8_4.c
Chip type           : ATmega16
Program type        : Application
Clock frequency     : 4.000000 MHz
Memory model        : Small
External SRAM size  : 0
Data Stack size     : 256
*********************************************/

// CodeVisionAVR C Compiler
// (C) 1998-2001 Pavel Haiduc, HP InfoTech S.R.L.

// I/O registers definitions for the ATmega16


#pragma used+
sfrb TWBR=0;
sfrb TWSR=1;
sfrb TWAR=2;
sfrb TWDR=3;
sfrb ADCL=4;
sfrb ADCH=5;
sfrw ADCW=4;      // 16 bit access
sfrb ADCSRA=6;
sfrb ADMUX=7;
sfrb ACSR=8;
sfrb UBRRL=9;
sfrb UCSRB=0xa;
sfrb UCSRA=0xb;
sfrb UDR=0xc;
sfrb SPCR=0xd;
sfrb SPSR=0xe;
sfrb SPDR=0xf;
sfrb PIND=0x10;
sfrb DDRD=0x11;
sfrb PORTD=0x12;
sfrb PINC=0x13;
sfrb DDRC=0x14;
sfrb PORTC=0x15;
sfrb PINB=0x16;
sfrb DDRB=0x17;
sfrb PORTB=0x18;
sfrb PINA=0x19;
sfrb DDRA=0x1a;
sfrb PORTA=0x1b;
sfrb EECR=0x1c;
sfrb EEDR=0x1d;
sfrb EEARL=0x1e;
sfrb EEARH=0x1f;
sfrw EEAR=0x1e;   // 16 bit access
sfrb UBRRH=0x20;
sfrb UCSRC=0X20;
sfrb WDTCR=0x21;
sfrb ASSR=0x22;
sfrb OCR2=0x23;
sfrb TCNT2=0x24;
sfrb TCCR2=0x25;
sfrb ICR1L=0x26;
sfrb ICR1H=0x27;
sfrb OCR1BL=0x28;
sfrb OCR1BH=0x29;
sfrw OCR1B=0x28;  // 16 bit access
sfrb OCR1AL=0x2a;
sfrb OCR1AH=0x2b;
sfrw OCR1A=0x2a;  // 16 bit access
sfrb TCNT1L=0x2c;
sfrb TCNT1H=0x2d;
sfrw TCNT1=0x2c;  // 16 bit access
sfrb TCCR1B=0x2e;
sfrb TCCR1A=0x2f;
sfrb SFIOR=0x30;
sfrb OSCCAL=0x31;
sfrb OCDR=0x31;
sfrb TCNT0=0x32;
sfrb TCCR0=0x33;
sfrb MCUCSR=0x34;
sfrb MCUCR=0x35;
sfrb TWCR=0x36;
sfrb SPMCR=0x37;
sfrb TIFR=0x38;
sfrb TIMSK=0x39;
sfrb GIFR=0x3a;
sfrb GICR=0x3b;
sfrb OCR0=0X3c;
sfrb SPL=0x3d;
sfrb SPH=0x3e;
sfrb SREG=0x3f;
#pragma used-

// Interrupt vectors definitions


// Needed by the power management functions (sleep.h)
#asm
	#ifndef __SLEEP_DEFINED__
	#define __SLEEP_DEFINED__
	.EQU __se_bit=0x40
	.EQU __sm_mask=0xB0
	.EQU __sm_powerdown=0x20
	.EQU __sm_powersave=0x30
	.EQU __sm_standby=0xA0
	.EQU __sm_ext_standby=0xB0
	.EQU __sm_adc_noise_red=0x10
	.SET power_ctrl_reg=mcucr
	#endif
#endasm


flash unsigned char led_7[10]={0x3F,0x06,0x5B,0x4F,0x66,0x6D,0x7D,0x07,0x7F,0x6F}; 
flash unsigned char position[6]={0xfe,0xfd,0xfb,0xf7,0xef,0xdf};

unsigned char	time[3];				// 时、分、秒计数单元
unsigned char	dis_buff[6];			// 显示缓冲区，存放要显示的6个字符的段码值
int	time_counter;				// 中断次数计数单元
unsigned char	posit;
bit	point_on, time_1s_ok;

void display(void)				// 6位LED数码管动态扫描函数
{
    PORTC = 0xff;	
	PORTA = led_7[dis_buff[posit]]; 
	if (point_on && (posit==2||posit==4)) PORTA |= 0x80;
	PORTC = position[posit]; 
	if (++posit >=6 ) posit = 0;
}

// Timer 0 比较匹配中断服务
interrupt [20] void timer0_comp_isr(void)
{
	display();  				// 调用LED扫描显示
	if (++time_counter>=500)
	{
		time_counter = 0;
		time_1s_ok = 1;
	}
}

void time_to_disbuffer(void)		// 时钟时间送显示缓冲区函数
{
	unsigned char i,j=0;
	for (i=0;i<=2;i++)
	{
		dis_buff[j++] = time[i] % 10;
	   	dis_buff[j++] = time[i] / 10;
	}
}

void main(void)
{
	PORTA=0x00;				// 显示控制I/O端口初始化
	DDRA=0xFF;
	PORTC=0x3F;
	DDRC=0x3F;
	// T/C0 初始化
	TCCR0=0x0B;				// 内部时钟，64分频（4M/64=62.5KHz），CTC模式
	TCNT0=0x00;
	OCR0=0x7C;		         // OCR0 = 0x7C(124),(124+1)/62.5=2ms
	TIMSK=0x02;				// 允许T/C0比较匹配中断

	time[2] = 23; time[1] = 58; time[0] = 55;		// 设时间初值23:58:55 
	posit = 0;
	time_to_disbuffer();

	#asm("sei")				// 开放全局中断

	while (1)
	{
		if (time_1s_ok)				// 1秒到
		{
			time_1s_ok = 0;
			point_on = ~point_on;
			if (++time[0] >= 60)	// 以下时间调整
			{
				time[0] = 0;
				if (++time[1] >= 60)
				{
					time[1] = 0;
					if (++time[2] >= 24) time[2] = 0;
				}
			}
			time_to_disbuffer();	// 新调整好的时间送显示缓冲区
		}
	}
}