模拟I2C编程：编写示例与延迟函数详解

void delay_ns(unsigned char nns)   //0.25us延时
{
int ntime=nns;
SysTick_Config(42);//0.25us产生一次中断,并对ntime减1
while(ntime);
SysTick->CTRL=0x00;
}
#define IIC_SDA0    GPIOB->BSRRH=GPIO_Pin_11   //sda=0
#define IIC_SDA1    GPIOB->BSRRL=GPIO_Pin_11   //sda=1
#define IIC_SCL0    GPIOB->BSRRH=GPIO_Pin_10
#define IIC_SCL1    GPIOB->BSRRL=GPIO_Pin_10

#define SDA_IN() GPIOB->MODER|=GPIO_Mode_IN<<4;  //sda输入
#define SDA_OUT()   GPIOB->MODER|=GPIO_Mode_OUT<<4;//sda输出



#define IN            1
#define OUT           0



#define  SetIicScl(x) do{if(x){IIC_SCL1;} \      
                         else {IIC_SCL0;}\
}while(0)

#define  SetIicSda(x) do{if(x){IIC_SDA1;} \
                         else {IIC_SDA0;}\
}while(0)

//设置SDA IO口方向

#define  SetIicSdaDir(x) do{if(x){SDA_IN();} \
                            else {SDA_OUT();}\
 }while(0)


#define  SoftDelay(i)  delay_ns(i)
#define ReadIicSda()  ((GPIOB->IDR&GPIO_Pin_11)!=0)?1:0  //判断接收到的bit
/***********************************************************************
 * Name: IicWriteDevice
 * Note: Write data to device
 * Para: device -> device address, buf->subaddress + data
 * Return : how many bytes have been write
*/
unsigned char IicWriteDevice(unsigned char device,unsigned char *buf, unsigned char cnt);

/***********************************************************************
 * Name: IicReadDevice
 * Note: Read data from device
 * Para: device->device address, subaddr->subaddress, acnt->subaddress lengh
 *       buf->read out data space, bcnt->read out data lengh
 * Return : write subaddress lengh
*/
unsigned char IicReadDevice(unsigned char device, unsigned char *subaddr, unsigned char acnt, unsigned char *buf, unsigned char bcnt);

void IIC_Init(void);

/***********************************************************************
 * Name: ReadIicSda()