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#include “bh1750.h”

static void BH1750_SDA_IN(void)
{
GPIO_InitTypeDef GPIO_InitStructure;

RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOC, ENABLE);

///<PC12.
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_12;
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN_FLOATING;
GPIO_Init(GPIOC, &GPIO_InitStructure);
}
static void BH1750_SDA_OUT(void)
{
GPIO_InitTypeDef GPIO_InitStructure;

RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOC, ENABLE);

///<PC12.
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_12;
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_Out_OD;
GPIO_Init(GPIOC, &GPIO_InitStructure);
}

//开始信号
static void IIC_Start(void)
{
BH1750_SDA_OUT();

BH1750_IIC_SDA = 1;	  	  
BH1750_IIC_SCL = 1;

delay_us(5);

BH1750_IIC_SDA = 0;   ///<START:when CLK is high,DATA change form high to low. 
delay_us(5);

BH1750_IIC_SCL = 0;   

}

//停止信号
static void IIC_Stop(void)
{
BH1750_SDA_OUT();

BH1750_IIC_SCL = 0;
BH1750_IIC_SDA = 0;  ///<STOP:when CLK is high DATA change form low to high.
delay_us(4);

BH1750_IIC_SCL=1; 
BH1750_IIC_SDA=1;    ///<·¢ËÍI2C×ÜÏß½áÊøÐźÅ.
delay_us(4);							   	

}

//等待应该信号
//return 0 应该成功

static uint8_t IIC_Wait_Ack(void)
{
uint8_t ucErrTime=0;

BH1750_SDA_IN();      

BH1750_IIC_SDA = 1;
delay_us(1);	   
BH1750_IIC_SCL = 1;
delay_us(1);

while(BH1750_READ_SDA)
{
	ucErrTime++;
	
	if(ucErrTime>250)
	{
		IIC_Stop();
		return 1;
	}
}

BH1750_IIC_SCL=0;  
return 0;  

}

//产生应答信号 —自己给个应答信号–不等待
static void IIC_Ack(void)
{
BH1750_IIC_SCL = 0;

BH1750_SDA_OUT();
BH1750_IIC_SDA = 0;

delay_us(2);
BH1750_IIC_SCL = 1;

delay_us(2);
BH1750_IIC_SCL = 0;

}
//不产生应答信号
static void IIC_NAck(void)
{
BH1750_IIC_SCL = 0;

BH1750_SDA_OUT();

BH1750_IIC_SDA = 1;
delay_us(2);

BH1750_IIC_SCL = 1;
delay_us(2);

BH1750_IIC_SCL = 0;

}

//发送一个字节数据
//return 1 有应答 0无应答
static void IIC_Send_Byte(uint8_t txd)
{
uint8_t t = 0;

BH1750_SDA_OUT(); 	    

BH1750_IIC_SCL = 0;

for(t=0; t<8; t++)
{
if((txd&0x80)>>7)
BH1750_IIC_SDA = 1;
else
BH1750_IIC_SDA = 0;

	txd<<=1; 	  
	delay_us(2);  
	
	BH1750_IIC_SCL = 1;
	delay_us(2); 
	
	BH1750_IIC_SCL = 0;	
	delay_us(2);

}
}

//读取一个字节的 ack 是否等待应答
static uint8_t IIC_Read_Byte(uint8_t ack)
{
uint8_t i,receive = 0;

BH1750_SDA_IN();

for(i=0;i<8;i++ )
{
BH1750_IIC_SCL = 0;
delay_us(2);

	BH1750_IIC_SCL = 1;
	
receive<<=1;
	
if(BH1750_READ_SDA)
		receive++;  
	
	delay_us(1); 

}
if (!ack)
IIC_NAck();
else
IIC_Ack();
return receive;
}

void bh_data_send(uint8_t command)
{
do
{
IIC_Start();
IIC_Send_Byte(BHAddWrite); //写器件地址
}while(IIC_Wait_Ack()); //等待应答

IIC_Send_Byte(command); //发送命了
IIC_Wait_Ack(); //等待应答
IIC_Stop(); // 停止
}

uint16_t bh_data_read(void)
{
uint16_t buf;

IIC_Start();                         
IIC_Send_Byte(BHAddRead);            //读器件地址
IIC_Wait_Ack();                      ///<µÈ´ý´Ó»úÓ¦´ð.
buf = IIC_Read_Byte(1);              ///<¶ÁÈ¡Êý¾Ý.
buf = buf<<8;                        ///<¶ÁÈ¡²¢±£´æ¸ß°ËλÊý¾Ý.
buf += 0x00ff&IIC_Read_Byte(0);      ///<¶ÁÈ¡²¢±£´æµÚ°ËλÊý¾Ý.
IIC_Stop();                          ///<·¢ËÍÍ£Ö¹ÐźÅ.
return buf; 

}