[嵌入式]stm32 IIC 硬件从机功能实现

在实际项目中stm32作为从机只需要读取数据，故目前只实现读函数

GPIO操作函数
void SDA_H(int id)
void SDA_L(int id)
int SDA_READ(int id)
SCL_READ(int id)
IIC_SDA_OUTPUT(int id)
void IIC_SDA_INPUT(int id)
void IIC_SDA_INT_ENABLA(void)

用到的宏定义
#define RECEIVE_DATA         		0x00
#define START_SIGNAL				0x01
#define STOP_SIGNAL					0x02
#define IDLE_SINGAL					0x03
#define INT_SINGAL					0x04

#define  MASTER_WRITE 				0x00
#define  MASTER_READ 				0x01
#define  ADDR_NOMATH	 			0x02

#define SLAVE_ADDR					0xAC

起始信号通过SDA IO中断判断
int wait_iic_start(int id)
{
	if (g_get_sda_int )
	{
		IIC_SDA_INPUT(id);
		IIC_INT_DISABLE(id);
		while (!SCL_READ(id));
		while (SDA_READ(id));
		iic_status.step = START_SIGNAL;
		 g_get_sda_int = 0;
	}
}

/*从机发送ACK*/
void iic_slave_send_ack(int id)
{
	while(SCL_READ(id));
	IIC_SDA_OUTPUT(id);
	SDA_L(id);
    while(!SCL_READ(id));
	while(SCL_READ(id));
	SDA_H(id);
	IIC_SDA_INPUT(id);

}

/*地址接收函数*/
uint8_t iic_revc_addr(int id)
{
	uint8_t cnt = 0;
	uint8_t recvaddr = 0;
	uint8_t iic_master_rw = 0;
	
	wait_iic_start(id);
	if (iic_status.step == START_SIGNAL)
	{
	    
		for (cnt = 0; cnt < 8; cnt++)
		{
			while(SCL_READ(id));
			while(!SCL_READ(id));
				
			recvaddr<<=1;
			if(SDA_READ(id))
			{
				recvaddr |=0x01;
			}
			
		}
		iic_master_rw = MASTER_WRITE;

		if (SLAVE_ADDR == recvaddr)  /*地址正确，从机发送ACK信号*/
		{
			iic_slave_send_ack(id);
			iic_status.step = RECEIVE_DATA;
			g_step = 1;
		}
		else
		{
			g_step = 2;
			while(SCL_READ(id));
			while(!SCL_READ(id));
			iic_status.step = IDLE_SINGAL;
			IIC_SDA_INT_ENABLA();
			return ADDR_NOMATH;
		}
		g_step = 3;
		return iic_master_rw;
		
	}

}

/*获取数据函数*/
uint8_t iic_recv_data(int id)
{
	uint8_t rw = 0;
	uint8_t recvData = 0;
	uint8_t bitcount = 0;
	uint8_t r0,r1;
	uint8_t data;
	int len;
	
	
	if (iic_status.step == IDLE_SINGAL)
		rw = iic_revc_addr(ID1_IIC);
	
	if (iic_status.step == RECEIVE_DATA)
	{
		g_step =4;
		while(!recvData)
		{
			for (bitcount = 0;bitcount < 8;bitcount++)
			{
				while(SCL_READ(id));
				while(!SCL_READ(id));
			
				r0 = SDA_READ(id);
			
				while(SCL_READ(id))
				{
					r1 =  SDA_READ(id);
					if (r0!=r1)
					{
						iic_status.step = STOP_SIGNAL;
						
						IIC_SDA_INT_ENABLA();				
						recvData= 1;
						return len;
					}
				}
				
			    data<<=1;				
				if(r0)
				{
					data |=1;
				}		
			}
			iic_slave_send_ack(id);
			iic_status.iicrxbuf[iic_status.rxnum] = data;
			iic_status.rxnum++;
		}
	}
}