ST IKS01A1 驱动程序分析

1.问题出现

　　我想把st官方的IKS01A1 板子的驱动程序移植到另一个板子上（stm32F767ZI NUCLEO），他原本的程序都是比较难懂，并且耦合度高，挺难移植的，但是我还是移植成功了，这里要对这个驱动代码进行分析。虽然我本来都比较喜欢正点原子那种简单易懂的程序，但是这种代码看了对自己的提高还是挺大的。

2.驱动代码

　　我以一个初始化函数为例。

首先主函数定义一个 static void *LSM6DS0_X_0_handle = NULL;

BSP_ACCELERO_Init(LSM6DS0_X_0, &LSM6DS0_X_0_handle);  //初始化函数

函数原型：这里就对 BSP_LSM6DS0_ACCELERO_Init(handle) 进行分析。

这里 &LSM6DS0_X_0_handle 赋值给 **handle ，传入的handle即LSM6DS0_X_0_handle 。

DrvStatusTypeDef BSP_ACCELERO_Init( ACCELERO_ID_t id, void **handle )
{

  *handle = NULL;

  switch(id)
  {
    case ACCELERO_SENSORS_AUTO:
    default:
    {
      /* Try to init the LSM6DS3 before */
      if( BSP_LSM6DS3_ACCELERO_Init(handle) == COMPONENT_ERROR )
      {
        /* Try to init the LSM6DS0 if we do not use the LSM6DS3 */
        if( BSP_LSM6DS0_ACCELERO_Init(handle) == COMPONENT_ERROR )
        {
          return COMPONENT_ERROR;
        }
      }
      break;
    }
    case LSM6DS0_X_0:
    {
      if( BSP_LSM6DS0_ACCELERO_Init(handle) == COMPONENT_ERROR )//我的板子执行这个
      {
        return COMPONENT_ERROR;
      }
      break;
    }
    case LSM6DS3_X_0:
    {
      if( BSP_LSM6DS3_ACCELERO_Init(handle) == COMPONENT_ERROR )
      {
        return COMPONENT_ERROR;
      }
      break;
    }
  }

  return COMPONENT_OK;
}

接下来是对static DrvStatusTypeDef BSP_LSM6DS0_ACCELERO_Init( void **handle )分析

源代码为

static DrvStatusTypeDef BSP_LSM6DS0_ACCELERO_Init( void **handle )
{
  ACCELERO_Drv_t *driver = NULL;

  if(ACCELERO_SensorHandle[ LSM6DS0_X_0 ].isInitialized == 1)
  {
    /* We have reached the max num of instance for this component */
    return COMPONENT_ERROR;
  }

  if ( Sensor_IO_Init() == COMPONENT_ERROR )
  {
    return COMPONENT_ERROR;
  }

  /* Setup sensor handle. */
  ACCELERO_SensorHandle[ LSM6DS0_X_0 ].who_am_i      = LSM6DS0_ACC_GYRO_WHO_AM_I;
  ACCELERO_SensorHandle[ LSM6DS0_X_0 ].ifType        = 0; /* I2C interface */
  ACCELERO_SensorHandle[ LSM6DS0_X_0 ].address       = LSM6DS0_ACC_GYRO_I2C_ADDRESS_HIGH;
  ACCELERO_SensorHandle[ LSM6DS0_X_0 ].instance      = LSM6DS0_X_0;
  ACCELERO_SensorHandle[ LSM6DS0_X_0 ].isInitialized = 0;
  ACCELERO_SensorHandle[ LSM6DS0_X_0 ].isEnabled     = 0;
  ACCELERO_SensorHandle[ LSM6DS0_X_0 ].isCombo       = 1;
  ACCELERO_SensorHandle[ LSM6DS0_X_0 ].pData         = ( void * )&ACCELERO_Data[ LSM6DS0_X_0 ];
  ACCELERO_SensorHandle[ LSM6DS0_X_0 ].pVTable       = ( void * )&LSM6DS0_X_Drv;
  ACCELERO_SensorHandle[ LSM6DS0_X_0 ].pExtVTable    = 0;

  LSM6DS0_X_0_Data.comboData = &LSM6DS0_Combo_Data[0];
  ACCELERO_Data[ LSM6DS0_X_0 ].pComponentData = ( void * )&LSM6DS0_X_0_Data;
  ACCELERO_Data[ LSM6DS0_X_0 ].pExtData       = 0;

  *handle = (void *)&ACCELERO_SensorHandle[ LSM6DS0_X_0 ];

  driver = ( ACCELERO_Drv_t * )((DrvContextTypeDef *)(*handle))->pVTable;

  if ( driver->Init == NULL )
  {
    memset((*handle), 0, sizeof(DrvContextTypeDef));
    *handle = NULL;
    return COMPONENT_ERROR;
  }

  if ( driver->Init( (DrvContextTypeDef *)(*handle) ) == COMPONENT_ERROR )
  {
    memset((*handle), 0, sizeof(DrvContextTypeDef));
    *handle = NULL;
    return COMPONENT_ERROR;
  }

  /* Configure interrupt lines for LSM6DS0 */
  LSM6DS0_Sensor_IO_ITConfig();

  return COMPONENT_OK;
}

重点对我画红圈的地方进行分析。

1.ACCELERO_SensorHandle[ LSM6DS0_X_0 ]

　　这其实是一个全局的设备参数结构体定义

　　原定义

　　static DrvContextTypeDef ACCELERO_SensorHandle[ ACCELERO_SENSORS_MAX_NUM ];

这个 DrvContextTypeDef 就是一个通用的外设内容结构体，可以关联到外设的所有参数

typedef struct
{

  /* Identity */
  uint8_t who_am_i;

  /* Configuration */
  uint8_t ifType;        /* 0 means I2C, 1 means SPI, etc. */
  uint8_t address;       /* Sensor I2C address (NOTE: Not a unique sensor ID). */
  uint8_t spiDevice;     /* Sensor Chip Select for SPI Bus */
  uint8_t instance;      /* Sensor instance (NOTE: Sensor ID unique only within its class). */
  uint8_t isInitialized; /* Sensor setup done. */
  uint8_t isEnabled;     /* Sensor ON. */
  uint8_t isCombo;       /* Combo sensor (component consists of more sensors). */

  /* Pointer to the Data */
  void *pData;
  /* Pointer to the Virtual Table */
  void *pVTable;
  /* Pointer to the Extended Virtual Table */
  void *pExtVTable;
} DrvContextTypeDef;

最后的三个还可以关联到这个设备的数据、驱动函数、扩展驱动函数

2.LSM6DS0_X_Drv

　　这是一个全局的驱动函数结构体，保存了这个设备的所有驱动。将所有的函数指针赋值到结构体。

　　定义：

typedef struct
{
  DrvStatusTypeDef ( *Init            ) ( DrvContextTypeDef* );
  DrvStatusTypeDef ( *DeInit          ) ( DrvContextTypeDef* );
  DrvStatusTypeDef ( *Sensor_Enable   ) ( DrvContextTypeDef* );
  DrvStatusTypeDef ( *Sensor_Disable  ) ( DrvContextTypeDef* );
  DrvStatusTypeDef ( *Get_WhoAmI      ) ( DrvContextTypeDef*, uint8_t* );
  DrvStatusTypeDef ( *Check_WhoAmI    ) ( DrvContextTypeDef* );
  DrvStatusTypeDef ( *Get_Axes        ) ( DrvContextTypeDef*, SensorAxes_t* );
  DrvStatusTypeDef ( *Get_AxesRaw     ) ( DrvContextTypeDef*, SensorAxesRaw_t* );
  DrvStatusTypeDef ( *Get_Sensitivity ) ( DrvContextTypeDef*, float* );
  DrvStatusTypeDef ( *Get_ODR         ) ( DrvContextTypeDef*, float* );
  DrvStatusTypeDef ( *Set_ODR         ) ( DrvContextTypeDef*, SensorOdr_t );
  DrvStatusTypeDef ( *Set_ODR_Value   ) ( DrvContextTypeDef*, float );
  DrvStatusTypeDef ( *Get_FS          ) ( DrvContextTypeDef*, float* );
  DrvStatusTypeDef ( *Set_FS          ) ( DrvContextTypeDef*, SensorFs_t );
  DrvStatusTypeDef ( *Set_FS_Value    ) ( DrvContextTypeDef*, float );
  DrvStatusTypeDef ( *Get_Axes_Status ) ( DrvContextTypeDef*, uint8_t* );
  DrvStatusTypeDef ( *Set_Axes_Status ) ( DrvContextTypeDef*, uint8_t* );
  DrvStatusTypeDef ( *Read_Reg        ) ( DrvContextTypeDef*, uint8_t, uint8_t* );
  DrvStatusTypeDef ( *Write_Reg       ) ( DrvContextTypeDef*, uint8_t, uint8_t );
  DrvStatusTypeDef ( *Get_DRDY_Status ) ( DrvContextTypeDef*, uint8_t* );
} ACCELERO_Drv_t;

ACCELERO_Drv_t LSM6DS0_X_Drv =
{
  LSM6DS0_X_Init,
  LSM6DS0_X_DeInit,
  LSM6DS0_X_Sensor_Enable,
  LSM6DS0_X_Sensor_Disable,
  LSM6DS0_X_Get_WhoAmI,
  LSM6DS0_X_Check_WhoAmI,
  LSM6DS0_X_Get_Axes,
  LSM6DS0_X_Get_AxesRaw,
  LSM6DS0_X_Get_Sensitivity,
  LSM6DS0_X_Get_ODR,
  LSM6DS0_X_Set_ODR,
  LSM6DS0_X_Set_ODR_Value,
  LSM6DS0_X_Get_FS,
  LSM6DS0_X_Set_FS,
  LSM6DS0_X_Set_FS_Value,
  LSM6DS0_X_Get_Axes_Status,
  LSM6DS0_X_Set_Axes_Status,
  LSM6DS0_X_Read_Reg,
  LSM6DS0_X_Write_Reg,
  LSM6DS0_X_Get_DRDY_Status
};

3.*handle = (void *)&ACCELERO_SensorHandle[ LSM6DS0_X_0 ];

　　这个的意思就是把赋值好的全局设备参数结构体地址传给自己定义的LSM6DS0_X_0_handle。

并且转换成（void *）；

4.driver = ( ACCELERO_Drv_t * )((DrvContextTypeDef *)(*handle))->pVTable;

　　首先把（*handle）强制转换 (DrvContextTypeDef *)。也就是这个时候相当于原来的ACCELERO_SensorHandle[LSM6DS0_X_0 ]。再把这个结构体的 void * pVTable,强制转换成ACCELERO_Drv_t *，相当于又变成了LSM6DS0_X_Drv。现在把这个 LSM6DS0_X_Drv结构体的地址赋值给driver。

5.driver->Init( (DrvContextTypeDef *)(*handle)

　　driver->Init( (DrvContextTypeDef *)(*handle)；现在就可以通过driver调用init来使用

static DrvStatusTypeDef LSM6DS0_X_Init( DrvContextTypeDef *handle );

同样，也可以通过他别的内容来该使用该设备的驱动函数。

3.思维导图

4.简单例子

　　main.c

#include <stdio.h>
#include "func.h"

static void *LSM6DS0_X_0_handle = NULL;

void Init_acc(void **handle);

int main(int argc, char *argv[])
{
    Init_acc(&LSM6DS0_X_0_handle);
    return 0;
}

void Init_acc(void **handle)
{
    //临时--初始化----设备结构体
    DrvContextTypeDef ACCELERO_SensorHandle;
    //设备驱动结构体初始化
    ACCELERO_Drv_t *driver=NULL ;

    //初始化一些信息
    ACCELERO_SensorHandle.who_am_i=110;

    //将驱动函数连接到设备的驱动
    ACCELERO_SensorHandle.pVTable=( void * )&LSM6DS0_X_Drv;

    //将刚刚初始化的信息传给handle,这样传进来的handle就会被赋值
    *handle =(void *)&ACCELERO_SensorHandle;

    //
    driver=(ACCELERO_Drv_t *)((DrvContextTypeDef *)(*handle))->pVTable;
    if(driver->Init == NULL)
    {
        printf("error
");
    }else {
        driver->Init( (DrvContextTypeDef *)(*handle));
    }

}

　　fun.c

#include "func.h"
#include "stdio.h"
#include "stdint.h"
void ACC_Init(DrvContextTypeDef *handle)
{
//    printf("Init LSM6DS0 %d
",cnt);
        printf("Init Handle->who am i : %d
",handle->who_am_i);
}
void ACC_DeInit(DrvContextTypeDef *handle)
{
//    printf("DeInit LSM6DS0 %d
",cnt);
}

//驱动结构体赋值，将函数关联到结构体中
ACCELERO_Drv_t LSM6DS0_X_Drv =
{
  ACC_Init,
  ACC_DeInit,
};

　　fun.h

#ifndef FUNC_H
#define FUNC_H
#include "stdint.h"

//定义设备内容结构体
typedef struct
{

  /* Identity */
  uint8_t who_am_i;

  /* Configuration */
  uint8_t ifType;        /* 0 means I2C, 1 means SPI, etc. */
  uint8_t address;       /* Sensor I2C address (NOTE: Not a unique sensor ID). */
  uint8_t spiDevice;     /* Sensor Chip Select for SPI Bus */
  uint8_t instance;      /* Sensor instance (NOTE: Sensor ID unique only within its class). */
  uint8_t isInitialized; /* Sensor setup done. */
  uint8_t isEnabled;     /* Sensor ON. */
  uint8_t isCombo;       /* Combo sensor (component consists of more sensors). */

  /* Pointer to the Data */
  void *pData;
  /* Pointer to the Virtual Table */
  void *pVTable;
  /* Pointer to the Extended Virtual Table */
  void *pExtVTable;

} DrvContextTypeDef;



//定义驱动结构体
typedef struct
{
  void ( *Init            ) (DrvContextTypeDef *handle);
  void ( *DeInit          ) (DrvContextTypeDef *handle);
} ACCELERO_Drv_t;



extern ACCELERO_Drv_t LSM6DS0_X_Drv;



#endif // FUNC_H

ST IKS01A1 驱动程序分析

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