demo_9_3.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>>中有关秒校时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_9_3.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[13]={0x3F,0x06,0x5B,0x4F,0x66,0x6D,	// 字型码
                      0x7D,0x07,0x7F,0x6F,0x77,0x7C,0x40};
			  					// 后3位为 "A"，"b"，"-"	
flash unsigned char position[8]={0x7f,0xbf,0xdf,0xef,0xf7,0xfb,0xfd,0xfe};

unsigned char	dis_buff[8];				// 显示缓冲区，存放要显示的8个字符的段码值
unsigned char	key_stime_counter;
unsigned char	posit;
bit	key_stime_ok;

void display(void)					// 8位LED数码管动态扫描函数
{
	PORTC = 0xff;
	PORTA = led_7[dis_buff[posit]]; 
	PORTC = position[posit]; 
	if (++posit >=8 ) posit = 0;
}

// Timer 0 比较匹配中断服务,2ms定时
interrupt [20] void timer0_comp_isr(void)
{
	display();						// 调用LED扫描显示
	if (++key_stime_counter >=5)
	{
		key_stime_counter = 0;
		key_stime_ok = 1;				// 10ms到
	}	
}


unsigned char read_keyboard()
{	
	static unsigned char key_state = 0, key_value, key_line;
    unsigned char key_return = 255,i;
	
	switch (key_state)
	{
		case 0:
			key_line = 0b00001000;
			for (i=1; i<=4; i++)					// 扫描键盘
			{	
				PORTD = ~key_line;					// 输出行线电平
				PORTD = ~key_line;					// 必须送2次！！！
                key_value = 0b00000111 & PIND;		// 读列电平
				if (key_value == 0b00000111)
					key_line <<= 1;				// 没有按键，继续扫描
				else
				{
					key_state++;					// 有按键，停止扫描
					break;						// 转消抖确认状态
				}
			}
			break;
		case 1:
			if (key_value == (0b00000111 & PIND))		// 再次读列电平，
			{
				switch (key_line | key_value)		// 与状态0的相同，确认按键
				{								// 键盘编码，返回编码值 
					case 0b00001110:
						key_return = 1;
						break;
					case 0b00001101:
						key_return = 2;
						break;
 					case 0b00001011:
						key_return = 3;
						break;
 					case 0b00010110:
						key_return = 4;
						break;
 					case 0b00010101:
						key_return = 5;
						break;
					case 0b00010011:
						key_return = 6;
						break;
 					case 0b00100110:
						key_return = 7;
						break;
 					case 0b00100101:
						key_return = 8;
						break;
					case 0b00100011:
						key_return = 9;
						break;
 					case 0b01000110:
						key_return = 10;
						break;
 					case 0b01000101:
						key_return = 0;
						break;
					case 0b01000011:
						key_return = 11;
						break;
				}
				key_state++;				// 转入等待按键释放状态
			}
			else
				key_state--;				// 两次列电平不同返回状态0，（消抖处理）
			break;						
		case 2:							// 等待按键释放状态
			PORTD = 0b00000111;			// 行线全部输出低电平
			PORTD = 0b00000111;			// 重复送一次
			if ( (0b00000111 & PIND) == 0b00000111)
				key_state=0;				// 列线全部为高电平返回状态0
			break;
	}
	return key_return;
}

void main(void)
{
	unsigned char i, key_temp;
	
	PORTA = 0x00;							// 显示控制I/O端口初始化
	DDRA = 0xFF;
	PORTC = 0xFF;
	DDRC = 0xFF;
	PORTD = 0xFF;							// 键盘接口初始化
	DDRD = 0xF8;							// PD2、PD1、PD0列线，输入方式，上拉有效
	// 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

	for (i=0; i<8 ;i++)
	{dis_buff[i]= 12;}		// LED初始显示8个"-"
	#asm("sei")			// 开放全局中断

	while (1)
	{
		if (key_stime_ok)				
		{
			key_stime_ok = 0;				// 10ms到
			key_temp = read_keyboard();		// 调用键盘接口函数读键盘
			if (key_temp != 255)
			{							// 有按键按下
				for (i=0; i<7; i++)
				{dis_buff[i] = dis_buff[i+1];}	// LED显示左移一位
				dis_buff[7] = key_temp; 		// 最右显示新按下键的键值
			}
		}
	}
}