stm32之IIC通信协议

  1 //3?ê??ˉIIC
  2 void IIC_Init(void)
  3 {                         
  4     GPIO_InitTypeDef GPIO_InitStructure;
  5     RCC_APB2PeriphClockCmd(    RCC_APB2Periph_GPIOB, ENABLE );    //ê1?üGPIOBê±?ó
  6        
  7     GPIO_InitStructure.GPIO_Pin = GPIO_Pin_6|GPIO_Pin_7;
  8     GPIO_InitStructure.GPIO_Mode = GPIO_Mode_Out_PP ;   //í?íìê?3?
  9     GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
 10     GPIO_Init(GPIOB, &GPIO_InitStructure);
 11     GPIO_SetBits(GPIOB,GPIO_Pin_6|GPIO_Pin_7);     //PB6,PB7 ê?3???
 12 }
 13 //2úéúIIC?eê?D?o?
 14 void IIC_Start(void)
 15 {
 16     SDA_OUT();     //sda??ê?3?
 17     IIC_SDA=1;            
 18     IIC_SCL=1;
 19     delay_us(4);
 20      IIC_SDA=0;//START:when CLK is high,DATA change form high to low 
 21     delay_us(4);
 22     IIC_SCL=0;//?ˉ×?I2C×ü??￡?×?±?·￠?í?ò?óê?êy?Y 
 23 }      
 24 //2úéúIICí￡?1D?o?
 25 void IIC_Stop(void)
 26 {
 27     SDA_OUT();//sda??ê?3?
 28     IIC_SCL=0;
 29     IIC_SDA=0;//STOP:when CLK is high DATA change form low to high
 30      delay_us(4);
 31     IIC_SCL=1; 
 32     IIC_SDA=1;//·￠?íI2C×ü???áê?D?o?
 33     delay_us(4);                                   
 34 }
 35 //μè′yó|′eD?o?μ?à′
 36 //·μ???μ￡o1￡??óê?ó|′e꧰ü
 37 //        0￡??óê?ó|′e3é1|
 38 u8 IIC_Wait_Ack(void)
 39 {
 40     u8 ucErrTime=0;
 41     SDA_IN();      //SDAéè???aê?è?  
 42     IIC_SDA=1;delay_us(1);       
 43     IIC_SCL=1;delay_us(1);     
 44     while(READ_SDA)
 45     {
 46         ucErrTime++;
 47         if(ucErrTime>250)
 48         {
 49             IIC_Stop();
 50             return 1;
 51         }
 52     }
 53     IIC_SCL=0;//ê±?óê?3?0        
 54     return 0;  
 55 } 
 56 //2úéúACKó|′e
 57 void IIC_Ack(void)
 58 {
 59     IIC_SCL=0;
 60     SDA_OUT();
 61     IIC_SDA=0;
 62     delay_us(2);
 63     IIC_SCL=1;
 64     delay_us(2);
 65     IIC_SCL=0;
 66 }
 67 //2?2úéúACKó|′e            
 68 void IIC_NAck(void)
 69 {
 70     IIC_SCL=0;
 71     SDA_OUT();
 72     IIC_SDA=1;
 73     delay_us(2);
 74     IIC_SCL=1;
 75     delay_us(2);
 76     IIC_SCL=0;
 77 }                                          
 78 //IIC·￠?íò???×??ú
 79 //·μ??′ó?úóD?Tó|′e
 80 //1￡?óDó|′e
 81 //0￡??Tó|′e              
 82 void IIC_Send_Byte(u8 txd)
 83 {                        
 84     u8 t;   
 85     SDA_OUT();         
 86     IIC_SCL=0;//à-μíê±?ó?aê?êy?Y′?ê?
 87     for(t=0;t<8;t++)
 88     {              
 89         //IIC_SDA=(txd&0x80)>>7;
 90         if((txd&0x80)>>7)
 91             IIC_SDA=1;
 92         else
 93             IIC_SDA=0;
 94         txd<<=1;       
 95         delay_us(2);   //??TEA5767?aèy???óê±??ê?±?D?μ?
 96         IIC_SCL=1;
 97         delay_us(2); 
 98         IIC_SCL=0;    
 99         delay_us(2);
100     }     
101 }         
102 //?á1??×??ú￡?ack=1ê±￡?·￠?íACK￡?ack=0￡?·￠?ínACK   
103 u8 IIC_Read_Byte(unsigned char ack)
104 {
105     unsigned char i,receive=0;
106     SDA_IN();//SDAéè???aê?è?
107     for(i=0;i<8;i++ )
108     {
109         IIC_SCL=0; 
110         delay_us(2);
111         IIC_SCL=1;
112         receive<<=1;
113         if(READ_SDA)receive++;   
114         delay_us(1); 
115     }                     
116     if (!ack)
117         IIC_NAck();//·￠?ínACK
118     else
119         IIC_Ack(); //·￠?íACK   
120     return receive;
121 }