demo_16_2.i

AVR原理与应用例程

/*****************************************************
File name           : demo_16_2.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


// CodeVisionAVR C Compiler
// (C) 1998-2006 Pavel Haiduc, HP InfoTech S.R.L.

// Prototypes for standard I/O functions


// CodeVisionAVR C Compiler
// (C) 1998-2002 Pavel Haiduc, HP InfoTech S.R.L.

// Variable length argument list macros



typedef char *va_list;





#pragma used+

char getchar(void);
void putchar(char c);
void puts(char *str);
void putsf(char flash *str);

char *gets(char *str,unsigned int len);

void printf(char flash *fmtstr,...);
void sprintf(char *str, char flash *fmtstr,...);
void snprintf(char *str, unsigned int size, char flash *fmtstr,...);
void vprintf (char flash * fmtstr, va_list argptr);
void vsprintf (char *str, char flash * fmtstr, va_list argptr);
void vsnprintf (char *str, unsigned int size, char flash * fmtstr, va_list argptr);
signed char scanf(char flash *fmtstr,...);
signed char sscanf(char *str, char flash *fmtstr,...);




                                   

            


#pragma used-

#pragma library stdio.lib


// CodeVisionAVR C Compiler
// (C) 1998-2000 Pavel Haiduc, HP InfoTech S.R.L.


#pragma used+

void delay_us(unsigned int n);
void delay_ms(unsigned int n);

#pragma used-





void I2C_init(void)
{
    PORTC.0 = 0;
    PORTA.0 = 0;
    DDRC.0 = 1;
    DDRA.0 = 1;
}

//产生启动信号
unsigned char I2C_start(void)
{
  DDRA.0 = 0;       
  delay_us(1);  
  DDRC.0 = 0;
  delay_us(1);
  DDRA.0 = 1;           
  delay_us(1);
  DDRC.0 = 1;         
  delay_us(1);  
  return 1;
}

//产生停止信号
void I2C_stop(void)
{
  DDRA.0 = 1;    
  delay_us(1);  
  DDRC.0 = 0;
  delay_us(1);
  DDRA.0 = 0;    
  delay_us(1);  
}

//向总线写一字节,并返回有无应答
unsigned char I2C_write(unsigned char c)
{
  unsigned char i,ack = 1;
  for(i=0;i<8;i++)  
  {
    if(c&0x80)
      DDRA.0 = 0;  
    else  
      DDRA.0 = 1;               
    DDRC.0 = 0;       
    delay_us(1);        
    DDRC.0 = 1; 
    c<<=1;
    delay_us(1);
  }
  DDRA.0 = 0;                
  delay_us(1);
  DDRC.0 = 0;
  delay_us(1);
  if(PINA.0)
    ack=0;     //失败
  DDRC.0 = 1;
  delay_us(1);
  return ack;  
}

//读一字节 ack: 1时应答，0时不应答
unsigned char I2C_read(unsigned char ack)
{
  unsigned char i,ret;
  DDRA.0 = 0;
  for(i=0;i<8;i++)
  {
    delay_us(1);          
    DDRC.0 = 1;                  
    delay_us(1);
    DDRC.0 = 0;                
    delay_us(1);
    ret<<=1;
    if(PINA.0)
      ret++;  
  }
  DDRC.0 = 1;    
  delay_us(1);
  if(ack)      //非应答
    DDRA.0 = 1;            
  else          //应答
    DDRA.0 = 0;
  delay_us(1);
  DDRC.0 = 0;
  delay_us(1);                  
  DDRC.0 = 1;                     
  delay_us(1);
  return(ret);  
}

// read a byte from the 24C256
unsigned char eeprom_read(unsigned int address)
{
    unsigned char data;
    I2C_start();						// 发起始信号
    I2C_write(0xa0);		// 发写从机写寻址字节
    I2C_write(address>>8);				// 发存储单元地址高字节
    I2C_write(address);					// 发存储单元地址低字节
    I2C_start();						// 发起始信号
    I2C_write(0xa0 | 1);	// 发从机读寻址字节
    data=I2C_read(0);					// 读一个字节数据，返回NO ACK
    I2C_stop();						// 发停止信号
    return data;
}

// write a byte to the 24C256
void eeprom_write(unsigned int address, unsigned char data)
{
    I2C_start();						// 发起始信号
    I2C_write(0xa0);		// 发写从机写寻址字节
    I2C_write(address>>8);				// 发存储单元地址高字节
    I2C_write(address);					// 发存储单元地址低字节
    I2C_write(data);					// 写一个字节数据到24C256
    I2C_stop();						// 发停止信号
    delay_ms(10);			// 等待10ms，保证24C256内部写操作完成再进行新操作
}

void main(void)
{
    unsigned char i;
    UCSRA=0x00;		// USART initialization
    UCSRB=0x18;		// Communication Parameters: 8 Data, 1 Stop, No Parity
    UCSRC=0x86;		// USART Receiver: On，USART Transmitter: On
    UBRRH=0x00;		// USART Mode: Asynchronous	，USART Baud Rate: 9600
    UBRRL=0x19;
    //================================================
    I2C_init();		  // initialize the I2C bus 
    eeprom_write(0x00aa,0x55);		// write the byte 55h at address 00AAh
    i = eeprom_read(0x00aa);		// read the byte from address 00AAh
    //================================================
    while (1)
    {
     	putchar(i);
       	delay_ms(250);
   	}
}