今天时间有限我就只贴代码了

myiic.c

#include "myi2c.h"//IIC.SCL->GPIOB6
//IIC.SDA->GPIOB7void IIC_Init(void)
{GPIO_InitTypeDef GPIO_InitStruct;__HAL_RCC_GPIOB_CLK_ENABLE();GPIO_InitStruct.Pin = GPIO_PIN_6|GPIO_PIN_7;GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_OD;GPIO_InitStruct.Pull = GPIO_PULLUP;GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_HIGH;HAL_GPIO_Init(GPIOB, &GPIO_InitStruct);IIC_SCL(1);IIC_SDA(1);
}void SDA_IN(void)
{GPIO_InitTypeDef GPIO_InitStruct;__HAL_RCC_GPIOB_CLK_ENABLE();GPIO_InitStruct.Pin = GPIO_PIN_7;GPIO_InitStruct.Mode = GPIO_MODE_AF_INPUT;GPIO_InitStruct.Pull = GPIO_NOPULL;HAL_GPIO_Init(GPIOB, &GPIO_InitStruct);	
}void SDA_OUT(void)
{ GPIO_InitTypeDef GPIO_InitStruct;__HAL_RCC_GPIOB_CLK_ENABLE();GPIO_InitStruct.Pin =  GPIO_PIN_7;GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_OD;GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_HIGH;HAL_GPIO_Init(GPIOB, &GPIO_InitStruct);
}void IIC_Start(void)
{SDA_OUT();     IIC_SDA(1);	  	  IIC_SCL(1);delay_us(10);IIC_SDA(0);     //START:when CLK is high,DATA change form high to low delay_us(10);IIC_SCL(0);     
}	  void IIC_Stop(void)
{SDA_OUT();IIC_SCL(0);IIC_SDA(0);//STOP:when CLK is high DATA change form low to highdelay_us(10);IIC_SCL(1); IIC_SDA(1);delay_us(10);	
}uint8_t IIC_Wait_Ack(void)
{uint8_t ucErrTime=0;SDA_IN();      IIC_SDA(1);delay_us(2);	   IIC_SCL(1);delay_us(2);	 while(IIC_SDAIN){ucErrTime++;if(ucErrTime>250){IIC_Stop();return 1;}}IIC_SCL(0);	   return 0;  
} void IIC_Ack(void)
{IIC_SCL(0);SDA_OUT();IIC_SDA(0);delay_us(5);IIC_SCL(1);delay_us(5);IIC_SCL(0);
}void IIC_NAck(void)
{IIC_SCL(0);SDA_OUT();IIC_SDA(1);delay_us(5);IIC_SCL(1);delay_us(5);IIC_SCL(0);
}					 				     void IIC_Send_Byte(uint8_t txd)
{                        uint8_t t;   SDA_OUT(); 	    IIC_SCL(0);for(t=0;t<8;t++)    {              if((txd&0x80)>>7)IIC_SDA(1);elseIIC_SDA(0);txd<<=1; 	  delay_us(5);   IIC_SCL(1);delay_us(5); IIC_SCL(0);	delay_us(5);}	 
} 	    uint8_t IIC_Read_Byte(unsigned char ack)
{unsigned char i,receive=0;SDA_IN();for(i=0;i<8;i++ ){IIC_SCL(0); delay_us(5);IIC_SCL(1);receive<<=1;if(IIC_SDAIN)receive++;   delay_us(4); }					 if (!ack)IIC_NAck();elseIIC_Ack(); //产生ACK   return receive;
}

myiic.h

#ifndef _MYI2C_H
#define _MYI2C_H#include "main.h"
#include "delay.h"#define IIC_SCL(x) HAL_GPIO_WritePin(GPIOB,GPIO_PIN_6,(GPIO_PinState)(x))  //IIC.SCL->GPIOB6
#define IIC_SDA(x) HAL_GPIO_WritePin(GPIOB,GPIO_PIN_7,(GPIO_PinState)(x))  //IIC.SDA->GPIOB7
#define IIC_SDAIN  HAL_GPIO_ReadPin(GPIOB,GPIO_PIN_7)void IIC_Init(void);                     		 
void IIC_Start(void);				             
void IIC_Stop(void);	  			           
void IIC_Send_Byte(uint8_t txd);			   
uint8_t IIC_Read_Byte(unsigned char ack);
uint8_t IIC_Wait_Ack(void); 				     
void IIC_Ack(void);			                 
void IIC_NAck(void);				           void SDA_IN(void);
void SDA_OUT(void);#endif

mcp4725.c

#include "MCP4725.h"void MCP4725_Init(void)
{IIC_Init();
}//使用快速模式写命令写DAC寄存器
void  MCP4725_WriteData_Voltage(uint16_t Vout)   //电压单位mV   (max:3299)
{uint8_t temp;uint16_t Dn;Dn = (4096*Vout)/VREF;  temp = (0x0F00 & Dn) >> 8;  //12位数据。0000XXXX XXXXXXXX IIC_Start();IIC_Send_Byte(0XC0);        //器件寻址，器件代码：1100； 地址位A2，A1，A0为 0 ， 0 ， 0；-> 1100 0000IIC_Wait_Ack();	 IIC_Send_Byte(temp); 	      //将高8位送到DAC寄存器IIC_Wait_Ack();	 IIC_Send_Byte(Dn);          //将低8位送到DAC寄存器IIC_Wait_Ack();	IIC_Stop();                //产生一个停止条件 	delay_ms(10);	
}void  MCP4725_WriteData_Digital(uint16_t data)   //12位数字量   (max:4095)
{uint8_t data_H=0,data_L=0;data_H = ( 0x0F00 & data) >> 8;data_L = 0X00FF & data ;IIC_Start();               //20usIIC_Send_Byte(0XC0);      //器件寻址，器件代码：1100； 地址位A2，A1，A0为 0 ， 0 ， 0；-> 1100 0000  15usIIC_Wait_Ack();	          //5usIIC_Send_Byte(data_H); 	IIC_Wait_Ack();	 IIC_Send_Byte(data_L);IIC_Wait_Ack();	IIC_Stop();               //产生一个停止条件  	20usdelay_us(10);	
}

mcp4725.h

#ifndef __Mcp4725_H
#define __Mcp4725_H#include "Myi2c.h"
#include "Delay.h"#define  VREF   3300void MCP4725_Init(void);
void MCP4725_WriteData_Digital(uint16_t data);
void MCP4725_WriteData_Voltage(uint16_t Vout);#endif

软件IIC就是移植得快，我试过很多次了这个能用。