twi.rar_MEGA128 TWI_TWI_mega128_sonar_声纳

#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); }