Atmega8实例全集

//ICC-AVR application builder : 2009-3-12 17:05:04 // Target : M8 // Crystal: 8.0000Mhz #include <iom8v.h> #include <macros.h> void port_init(void) { PORTB = 0x00; DDRB = 0x00; PORTC = 0x00; //m103 output only DDRC = 0x00; PORTD = 0x00; DDRD = 0x00; } //call this routine to initialize all peripherals void init_devices(void) { //stop errant interrupts until set up CLI(); //disable all interrupts port_init(); MCUCR = 0x00; GICR = 0x00; TIMSK = 0x00; //timer interrupt sources SEI(); //re-enable interrupts //all peripherals are now initialized } /************************************************************************* 用 途:iic发送接收 Taget :mega8 crystal :8M 介 绍:PC4-SDA PC5-SCK/SCL //*********************************************************************** I2C 状态定义 MT 主方式传输 MR 主方式接受 ***************************/ #define START 0x08 #define RE_START 0x10 #define MT_SLA_ACK 0x18 #define MT_SLA_NOACK 0x20 #define MT_DATA_ACK 0x28 #define MT_DATA_NOACK 0x30 #define MR_SLA_ACK 0x40 #define MR_SLA_NOACK 0x48 #define MR_DATA_ACK 0x50 #define MR_DATA_NOACK 0x58 #define RD_DEVICE_ADDR 0xA1 //前4位器件固定,后三位看连线,最后1位是读写指令位 #define WD_DEVICE_ADDR 0xA0 #define Start() (TWCR=(1<<TWINT)|(1<<TWSTA)|(1<<TWEN)) //启动I2C #define Stop() (TWCR=(1<<TWINT)|(1<<TWSTO)|(1<<TWEN)) //停止I2C #define Wait() {while(!(TWCR&(1<<TWINT)));} //等待中断发生 #define TestAck() (TWSR&0xf8) //观察返回状态 #define SetAck (TWCR|=(1<<TWEA)) //做出ACK应答 #define SetNoAck (TWCR&=~(1<<TWEA)) //做出Not Ack应答 #define Twi() (TWCR=(1<<TWINT)|(1<<TWEN)) //启动I2C #define Write8Bit(x) {TWDR=(x);TWCR=(1<<TWINT)|(1<<TWEN);} //写数据到TWDR /*延时子程序*/ void delay_ms(int time) { int i; for(;time>0;time--) for(i=0;i<1000;i++); } //初始化 void iic_init() { TWBR= 0x20; //设置波特率 TWSR= 0x00; //设置预分频比 TWCR= 0x44; //使能应答，使能TWI DDRC|=(1<<PC4)|(1<<PC5); PORTC|=(1<<PC4)|(1<<PC5); } /********************************************* I2C总线写一个字节 返回0:写成功 返回1:写失败 **********************************************/ unsigned char iic_write(unsigned char Wdata,unsigned char RegAddress) { Start(); //I2C启动 Wait(); if(TestAck()!=START) return 1; //ACK Write8Bit(WD_DEVICE_ADDR); //写I2C从器件地址和写方式 Wait(); if(TestAck()!=MT_SLA_ACK) return 1; //ACK Write8Bit(RegAddress); //写器件相应寄存器地址 Wait(); if(TestAck()!=MT_DATA_ACK) return 1; //ACK Write8Bit(Wdata); //写数据到器件相应寄存器 Wait(); if(TestAck()!=MT_DATA_ACK) return 1; //ACK Stop(); //I2C停止 delay_ms(100); //延时 return 0; } /********************************************* I2C总线读一个字节 返回非0:读成功 返回0:读失败 **********************************************/ unsigned char iic_read(unsigned RegAddress) { unsigned char temp; Start();//I2C启动 Wait(); if (TestAck()!=START) return 1; //ACK Write8Bit(WD_DEVICE_ADDR); //写I2C从器件地址和写方式 Wait(); if (TestAck()!=MT_SLA_ACK) return 1; //ACK Write8Bit(RegAddress); //写器件相应寄存器地址 Wait(); if (TestAck()!=MT_DATA_ACK) return 1; Start(); //I2C重新启动 Wait(); if (TestAck()!=RE_START) return 1; Write8Bit(RD_DEVICE_ADDR); //写I2C从器件地址和读方式 Wait(); if(TestAck()!=MR_SLA_ACK) return 1; //ACK Twi(); //启动主I2C读方式 Wait(); if(TestAck()!=MR_DATA_NOACK) return 1; //ACK temp=TWDR; //读取I2C接收数据 Stop(); //I2C停止 return temp; } //**************************************************************************** void main() { unsigned char i,j; port_init(); init_devices(); iic_init(); i=iic_write(0xaa,0X10);//在0X10地址写入数据0XAA if (i==1) PORTB=0x1;//若写入失败(i=1),B口0x01；若写入成功，B口输出0X02 else PORTB=0x2; j=iic_read(0X10);//读出0x10地址的数据 if(j==1) PORTD=0xff; //若读出失败(j=1),D口全灭；若读出成功，D口输出0XAA else PORTD=j; while(1) { ; } }