首先送上wiringPi库关于i2c的介绍：http://wiringpi.com/reference/i2c-library/

1、首先查看wiringPi库I2C相关的函数：

int wiringPiI2CSetup (int devId) ;初始化wiringPi库i2c，devId是i2c设备地址，返回值是linux的文件描述符

int wiringPiI2CRead (int fd) ;直接读取数据，fd是wiringPiI2CSetup函数的返回值，返回值是读到的数据

int wiringPiI2CWrite (int fd, int data) ;直接写数据，fd同上，data是写入的数据

int wiringPiI2CWriteReg8 (int fd, int reg, int data) ;写数据到8位寄存器，fd同上，reg寄存器地址，data要写入的数据

int wiringPiI2CWriteReg16 (int fd, int reg, int data) ;写数据到16位寄存器，fd同上，reg寄存器地址，data要写入的数据

int wiringPiI2CReadReg8 (int fd, int reg) ;从寄存器读取8位数据，fd同上，reg寄存器地址，返回值读取到的数据

int wiringPiI2CReadReg16 (int fd, int reg) ;从寄存器读取16位数据，fd同上，reg寄存器地址，返回值读取到的数据

2、设备相关信息

在这里，以罗姆的低功耗气压传感器BM1383AGLV为例说明，关于传感器更多信息，查看罗姆(ROHM)低功耗气压传感器BM1383AGLV了解。

3、编程

分两个文件展开 i2c_bm1383.h 和i2c_bm1383.c，i2c_bm1383.h是关于传感器的宏定义，i2c_bm1383.c里面是主要的驱动代码。

i2c_bm1383.h文件详细代码：

#ifndef __I2C_BM1383_H__
#define __I2C_BM1383_H__

#include <stdio.h>
#include <stdbool.h>

typedef signed char int8_t;
typedef unsigned char uint8_t;
typedef signed int int16_t;
typedef unsigned int uint16_t;
typedef signed long int int32_t;
typedef unsigned long int uint32_t;
typedef signed long long int int64_t;
typedef unsigned long long int uint64_t;

#define BM1383AGLV_I2C_ADDR          0x5D
 
#define BM1383AGLV_ID1               0x0F
#define BM1383AGLV_ID2               0x10
 
#define BM1383AGLV_PWR_DOWN          0x12
          //PWR_DOWN[0]
        #define POWER_DOWN                  0x00
        #define ACTIVE                      0x01 
          //Reserved[7:1]
 
#define BM1383AGLV_RESET             0x13
          //RSTB[0]
        #define MEASUREMENT_RESET           0x00
        #define MEASUREMENT_ACTIVE          0x01
          //Reserved[7:1]
 
#define BM1383AGLV_MODE_CONTROL      0x14
          //mode [1:0]
        #define  MODE_STAND_BY              0x00
        #define  MODE_ONE_SHOT              0x01
        #define  MODE_CONTINUOUS            0x02
        #define  MODE_PROHIBITION           0x03
          //Reserved[2]
          //Reserved[3]
        #define  DEFAULT_1                  0x08
          //DRDY pin Enable[4]
        #define  DRDY_PIN_ENABLE            0x10
        #define  DRDY_PIN_DISABLE           0x00
          //Set the average number of measurement data[7:5]
        #define  AVE_NUM_1                  0x00
        #define  AVE_NUM_2                  0x20
        #define  AVE_NUM_4                  0x40
        #define  AVE_NUM_8                  0x60
        #define  AVE_NUM_16                 0x80
        #define  AVE_NUM_32                 0xA0
        #define  AVE_NUM_64                 0xC0
        #define  AVE_NUM_INHIBIT            0xE0
 
#define BM1383AGLV_STATUS            0x19
          //Pressure and temperature measurement data ready bit[0]
        #define DATA_OUTPUT_AVAILABLE       0x01
        #define DATA_OUTPUT_NOT_AVAILABLE   0x00
          //Reserved[7:1]
 
#define BM1383AGLV_PRESSURE_MSB      0x1A
#define BM1383AGLV_PRESSURE_LSB      0x1B
#define BM1383AGLV_PRESSURE_DEC      0x1C
          //Pressure data output (decimal extension 6bit)[7:2]
          //Reserved[1:0]
 
#define BM1383AGLV_TEMPERATURE_MSB   0x1D
#define BM1383AGLV_TEMPERATURE_LSB   0x1E


bool BM1383AGLVCheck(void);
void BM1383AGLVInit(void);
void BM1383AGLVRead(void);



#endif

i2c_bm1383.c文件详细代码：

#include <wiringPi.h>
#include <wiringPiI2C.h>

#include "i2c_bm1383.h"


int i2c_fd;

bool BM1383AGLVCheck(void)
{
  uint16_t chip_id=0;
  
  chip_id=wiringPiI2CReadReg16(i2c_fd,BM1383AGLV_ID1);
    
  if(chip_id==0x32E0)
  {
    return true;
  }
  else
  {
    return false;
  }
}

void BM1383AGLVInit(void)
{
    wiringPiI2CWriteReg8(i2c_fd,BM1383AGLV_PWR_DOWN,ACTIVE);      //设置芯片上电
    delay(5);//延时必须大于2ms
    wiringPiI2CWriteReg8(i2c_fd,BM1383AGLV_RESET,MEASUREMENT_ACTIVE);     //启动测量功能
    wiringPiI2CWriteReg8(i2c_fd,BM1383AGLV_MODE_CONTROL,MODE_CONTINUOUS
                                                        |DEFAULT_1
                                                        |DRDY_PIN_DISABLE
                                                        |AVE_NUM_8);     
    //持续测量模式、每次测量8次、不使能DRDY引脚 
}

void BM1383AGLVRead(void)
{
    uint32_t pressure_count=0;
    uint8_t pressure_m , pressure_l,pressure_d;
    float pressure;
	 
    uint32_t temperture_count=0;
    uint8_t temperture_m , temperture_l;
    float temperture;
	 
   while(wiringPiI2CReadReg8(i2c_fd,BM1383AGLV_STATUS)&DATA_OUTPUT_AVAILABLE!=DATA_OUTPUT_AVAILABLE);//等待当前测量完成
	  
    pressure_m=wiringPiI2CReadReg8(i2c_fd,BM1383AGLV_PRESSURE_MSB);
    pressure_l=wiringPiI2CReadReg8(i2c_fd,BM1383AGLV_PRESSURE_LSB);
    pressure_d=wiringPiI2CReadReg8(i2c_fd,BM1383AGLV_PRESSURE_DEC);
	  
    pressure_d=pressure_d>>2;//高6位有效
	  
    pressure_count=pressure_m<<14;
    pressure_count+=pressure_l<<6;
    pressure_count+=pressure_d;
	 
    pressure=pressure_count/2048.0;
	 	 
    temperture_m=wiringPiI2CReadReg8(i2c_fd,BM1383AGLV_TEMPERATURE_MSB);
    temperture_l=wiringPiI2CReadReg8(i2c_fd,BM1383AGLV_TEMPERATURE_LSB);
	  
    temperture_count=temperture_m<<8;
    temperture_count+=temperture_l;
	  
    temperture=temperture_count/32.0;
	  
    printf("Pressure:%.2f hPa  Temperture:%f ℃\n",pressure,temperture); 
}

int main()
{
    bool isexist;

    wiringPiSetup(); //初始化wiringPi库
    i2c_fd = wiringPiI2CSetup(BM1383AGLV_I2C_ADDR);

    while(!BM1383AGLVCheck())
    {
    	printf("no exist\n" );
    	delay(5000);
    }    	
    printf("exist\n" );
    
    BM1383AGLVInit();

    while(1)
    {
	BM1383AGLVRead();
    
    	delay(5000);

    	printf("\n");
    }

    return 0;
}

4、编译

gcc -o i2c_bm1383 i2c_bm1383.c i2c_bm1383.h -lwiringPi

5、查看结果

至此，树莓派使用wiringPi库驱动i2c设备完成。