sonarset.c

mega128的twi代码

#include "sonarset.h"
/**********************************超声波操作**************************************/
//从指定超声波的指定寄存器读取数据
unsigned char i2c_read(unsigned char address, unsigned char reg)
{
    unsigned char read_data = 0;

 //按照i2c协议
	TWCR = 0xA4;			// send a start bit on i2c bus
	while(!(TWCR & 0x80));	// wait for confirmation of transmit

	TWDR = address;			// load address of i2c device
	TWCR = 0x84;			// transmit
	while(!(TWCR & 0x80));	// wait for confirmation of transmit

	TWDR = reg;			    // send register number to read from
	TWCR = 0x84;			// transmit
	while(!(TWCR & 0x80));	// wait for confirmation of transmit



	TWCR = 0xA4; 			// send repeated start bit
	while(!(TWCR & 0x80));	// wait for confirmation of transmit

	TWDR = address+1;		// transmit i2c address with readbit set
	TWCR = 0xC4;			// clear transmit interupt flag
	while(!(TWCR & 0x80));	// wait for confirmation of transmit

	TWCR = 0x84;			// transmit, nack (last byte request)
	while(!(TWCR & 0x80));	// wait for confirmation of transmit
	read_data = TWDR;		// and grab the target data
	TWCR = 0x94;			// send a stop bit on i2c bus

	return read_data;

}

//向指定超声波的指定寄存器写入命令字
//参数依次为：I2C地址,设备寄存器号（0-5），写入的一个字节数据
void i2c_transmit(unsigned char address, unsigned char reg, unsigned char data)
{
	TWCR = 0xA4;			// send a start bit on i2c bus
	while(!(TWCR & 0x80));	// wait for confirmation of transmit

	TWDR = address;			// load address of i2c device
	TWCR = 0x84;			// transmit
	while(!(TWCR & 0x80));	// wait for confirmation of transmit

	TWDR = reg;             // load number of register
	TWCR = 0x84;			// transmit
	while(!(TWCR & 0x80));	// wait for confirmation of transmit

	TWDR = data;            // load data to transmit
	TWCR = 0x84;			// transmit
	while(!(TWCR & 0x80));	// wait for confirmation of transmit

	TWCR = 0x94;			// stop bit
}

//将地址值为source的超声波改为destination
//新设备的初始地址是确定的，把某个超声波设备连接后，写入唯一的目标地址。I2C总线上最多可以有16个设备，地址从0xE0-oxFE.
//该地址中，最后2位标示读或写，0标示读。
void addr_change(unsigned char source,unsigned char destination)
{

    i2c_transmit(source, 0, 0xA0);
    i2c_transmit(source, 0, 0xAA);
    i2c_transmit(source, 0, 0xA5);
    i2c_transmit(source, 0, destination);

}

//超声波的速度初始化
void i2c_init(void)
{
	TWBR = 16;//TWBR为寄存器，初始化I2C的通信速度
}


void portinit(void)
{
	PORTB=0XFF;
	DDRB=0XFF;
}
void timerinit(void)
{
	TCCR1A=0Xa2;
	TCCR1B=0X19;//快速pwm，比较区配是oc0置位
    ICR1=0X0019;//设置top值，决定pwm频率,此时为8mhz/32=250khz
 
}

void init_device(void)
{
	
	portinit();
  timerinit();
 
	MCUCR = 0x00;

  //  TIMSK = 0x03;  ///
   
}
void DelayMs(int ms)
 { int i;
  for(i=0;i<ms;i++) 
 _delay_loop_2(8*250); 
 }

 
void main(void)
{
unsigned char i,j,m,n;
unsigned int length0,length1,length2,length4;
i2c_init();  //设定波特率
init_device();
OCR1A=0x000C;   //不得超过icr1值，表示占空比
OCR1B=0x000C; 
//addr_change(ADDR_0,ADDR_4);    //将sonar地址改为0xE2
for(i=0;i<15;i++)
{
DelayMs(5000);
}
OCR1B=0X000E;
//i2c_transmit(ADDR_0,0,0X51); //向0号寄存器写入命令值0x51，测量单位为厘米
//i2c_transmit(ADDR_1,0,0X51);

do
{
i2c_transmit(ADDR_0,0,0X51); 
i2c_transmit(ADDR_1,0,0X51);
while(0xff==i2c_read(ADDR_0,0));   //通过读取0号寄存器的值是否为0xff判断发送超声波是否结束
i=i2c_read(ADDR_0,2); // 读取高8位值
length0=0|i;    //扩充为16位
length0=i<<8;  // 左移八位
i=i2c_read(ADDR_0,3);  //读低8位值
length0|=i;  //扩充为16位 
/*length0=i2c_read(ADDR_0,2);
length0=length0<<8;
length0+=i2c_read(ADDR_0,3);*/

/*m=i2c_read(ADDR_0,4);
length2=0|m;
length2=m<<8;
m=i2c_read(ADDR_0,5);
length2|=m;*/

while(0xff==i2c_read(ADDR_1,0));
j=i2c_read(ADDR_1,2); // 读取高8位值
length1=0|j;    //扩充为16位
length1=j<<8;  // 左移八位
j=i2c_read(ADDR_1,3);  //读低8位值
length1|=j;  //扩充为16位

/*n=i2c_read(ADDR_1,4);
length4=0|n;
length4=n<<8;
n=i2c_read(ADDR_1,5);
length4|=n;

while(length0>=40||length1>=40);
//OCR1A=0x000f;   //不得超过icr1值，表示占空比
//OCR1B=0x0011;   //同上
//DelayMs(5000);
//OCR1B=0X0011;

/*if(length0<=40||length1<=40);
{
OCR1A=0x000c;
OCR1B=0x000c;
}
*/
}
while(length0>=50||length1>=50);
OCR1A=0x000c;
OCR1B=0X000c;
while(1);	
}