Reading Accelerometer and Gyroscope data from STM32F3 discovery board

I've made some experiments using the STM32F3 discovery board, which is amazing by the way, and the mems(Micro ElectroMechnical Systems) in the board.

For more information about the board check this link where you will find all the technical hardware and software examples made with many IDEs.
The main idea of this article is to make a standalone IMU (Inertial Measurement Unit) using only the STM32F3 board, because it has all the necessary hardware for making a complete 9 DOF IMU.

To do so I need to read both of the Gyroscope and the accelerometer data collected in a way so I can send later to the PC using VCP (USB CDC).

I started with the VCP example for the STM32303c eval board, you can find here
And then I add both of stm32f3_discovery_lsm303dlhc.c and stm32f3_discovery_l3gd20.c, this two file could be found in the utitli folder of the firmware support for the STM32F3 board can be found here.

Then later I found this great files to give more abstract function to deal with the mems.

The complete project from here

Accelerometer.c

#ifndef _ACC_C_
#define _ACC_C_

#define LSM_Acc_Sensitivity_2g     (float)     1.0f            /*!< accelerometer sensitivity with 2 g full scale [LSB/mg] */
#define LSM_Acc_Sensitivity_4g     (float)     0.5f            /*!< accelerometer sensitivity with 4 g full scale [LSB/mg] */
#define LSM_Acc_Sensitivity_8g     (float)     0.25f           /*!< accelerometer sensitivity with 8 g full scale [LSB/mg] */
#define LSM_Acc_Sensitivity_16g    (float)     0.0834f         /*!< accelerometer sensitivity with 12 g full scale [LSB/mg] */

#include "Accelerometer.h"
#include "stm32f3_discovery_lsm303dlhc.h"
/**
  * @brief  Configure the Mems to Accelerometer MEMS.
  * @param  None
  * @retval None
  */
void Acc_Config(void)
{
  LSM303DLHCAcc_InitTypeDef LSM303DLHCAcc_InitStructure;
  LSM303DLHCAcc_FilterConfigTypeDef LSM303DLHCFilter_InitStructure;
    
   /* Fill the accelerometer structure */
  LSM303DLHCAcc_InitStructure.Power_Mode = LSM303DLHC_NORMAL_MODE;
  LSM303DLHCAcc_InitStructure.AccOutput_DataRate = LSM303DLHC_ODR_50_HZ;
  LSM303DLHCAcc_InitStructure.Axes_Enable= LSM303DLHC_AXES_ENABLE;
  LSM303DLHCAcc_InitStructure.AccFull_Scale = LSM303DLHC_FULLSCALE_2G;
  LSM303DLHCAcc_InitStructure.BlockData_Update = LSM303DLHC_BlockUpdate_Continous;
  LSM303DLHCAcc_InitStructure.Endianness=LSM303DLHC_BLE_LSB;
  LSM303DLHCAcc_InitStructure.High_Resolution=LSM303DLHC_HR_ENABLE;
  /* Configure the accelerometer main parameters */
  LSM303DLHC_AccInit(&LSM303DLHCAcc_InitStructure);
  
  /* Fill the accelerometer LPF structure */
  LSM303DLHCFilter_InitStructure.HighPassFilter_Mode_Selection =LSM303DLHC_HPM_NORMAL_MODE;
  LSM303DLHCFilter_InitStructure.HighPassFilter_CutOff_Frequency = LSM303DLHC_HPFCF_16;
  LSM303DLHCFilter_InitStructure.HighPassFilter_AOI1 = LSM303DLHC_HPF_AOI1_DISABLE;
  LSM303DLHCFilter_InitStructure.HighPassFilter_AOI2 = LSM303DLHC_HPF_AOI2_DISABLE;

  /* Configure the accelerometer LPF main parameters */
  LSM303DLHC_AccFilterConfig(&LSM303DLHCFilter_InitStructure);
}

/**
* @brief Read LSM303DLHC output register, and calculate the acceleration ACC=(1/SENSITIVITY)* (out_h*256+out_l)/16 (12 bit rappresentation)
* @param pnData: pointer to float buffer where to store data
* @retval None
*/
void Acc_ReadData(float* pfData)
{
  int16_t pnRawData[3];
  uint8_t ctrlx[2];
  float LSM_Acc_Sensitivity = LSM_Acc_Sensitivity_2g;
  uint8_t buffer[6], cDivider;
  uint8_t i = 0;
  
  /* Read the register content */
  LSM303DLHC_Read(ACC_I2C_ADDRESS, LSM303DLHC_CTRL_REG4_A, ctrlx,2);
  LSM303DLHC_Read(ACC_I2C_ADDRESS, LSM303DLHC_OUT_X_L_A, buffer, 6);
 
  
  if(ctrlx[1]&0x40)
    cDivider=64;
  else
    cDivider=16;

  /* check in the control register4 the data alignment*/
  if(!(ctrlx[0] & 0x40) || (ctrlx[1] & 0x40)) /* Little Endian Mode or FIFO mode */
  {
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Gyro.c



#ifndef _GYRO_C_
#define _GYRO_C_

#define L3G_Sensitivity_250dps     (float)   114.285f         /*!< gyroscope sensitivity with 250 dps full scale [LSB/dps] */
#define L3G_Sensitivity_500dps     (float)    57.1429f        /*!< gyroscope sensitivity with 500 dps full scale [LSB/dps] */
#define L3G_Sensitivity_2000dps    (float)    14.285f       /*!< gyroscope sensitivity with 2000 dps full scale [LSB/dps] */

#include "Gyro.h"
#include "stm32f3_discovery_l3gd20.h"

/**
  * @brief  Configure the Mems to gyroscope application.
  * @param  None
  * @retval None
  */
void GyroConfig(void)
{
  L3GD20_InitTypeDef L3GD20_InitStructure;
  L3GD20_FilterConfigTypeDef L3GD20_FilterStructure;
  
  /* Configure Mems L3GD20 */
  L3GD20_InitStructure.Power_Mode = L3GD20_MODE_ACTIVE;
  L3GD20_InitStructure.Output_DataRate = L3GD20_OUTPUT_DATARATE_1;
  L3GD20_InitStructure.Axes_Enable = L3GD20_AXES_ENABLE;
  L3GD20_InitStructure.Band_Width = L3GD20_BANDWIDTH_4;
  L3GD20_InitStructure.BlockData_Update = L3GD20_BlockDataUpdate_Continous;
  L3GD20_InitStructure.Endianness = L3GD20_BLE_LSB;
  L3GD20_InitStructure.Full_Scale = L3GD20_FULLSCALE_500; 
  L3GD20_Init(&L3GD20_InitStructure);
   
  L3GD20_FilterStructure.HighPassFilter_Mode_Selection =L3GD20_HPM_NORMAL_MODE_RES;
  L3GD20_FilterStructure.HighPassFilter_CutOff_Frequency = L3GD20_HPFCF_0;
  L3GD20_FilterConfig(&L3GD20_FilterStructure) ;
  
  L3GD20_FilterCmd(L3GD20_HIGHPASSFILTER_ENABLE);
}

/**
  * @brief  Calculate the angular Data rate Gyroscope.
  * @param  pfData : Data out pointer
  * @retval None
  */
void GyroReadAngRate (float* pfData)
{
  uint8_t tmpbuffer[6] ={0};
  int16_t RawData[3] = {0};
  uint8_t tmpreg = 0;
  float sensitivity = 0;
  int i =0;

  L3GD20_Read(&tmpreg,L3GD20_CTRL_REG4_ADDR,1);
  
  L3GD20_Read(tmpbuffer,L3GD20_OUT_X_L_ADDR,6);
  
  /* check in the control register 4 the data alignment (Big Endian or Little Endian)*/
  if(!(tmpreg & 0x40))
  {
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main.c





/**
  ******************************************************************************
  * @file    main.c
  * @author  MCD Application Team
  * @version V4.0.0
  * @date    21-January-2013
  * @brief   Virtual Com Port Demo main file
  ******************************************************************************
  * @attention
  *
  **
  * Licensed under MCD-ST Liberty SW License Agreement V2, (the "License");
  * You may not use this file except in compliance with the License.
  * You may obtain a copy of the License at:
  *
  *        http://www.st.com/software_license_agreement_liberty_v2
  *
  * Unless required by applicable law or agreed to in writing, software 
  * distributed under the License is distributed on an "AS IS" BASIS, 
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  *
  ******************************************************************************
  */


/* Includes ------------------------------------------------------------------*/
#include "hw_config.h"
#include "usb_lib.h"
#include "usb_desc.h"
#include "usb_pwr.h"
#include "Accelerometer.h"
#include "Gyro.h"
#include 
/* Private typedef -----------------------------------------------------------*/
/* Private define ------------------------------------------------------------*/
/* Private macro -------------------------------------------------------------*/
/* Private variables ---------------------------------------------------------*/
float AccData[3];
float GyroData[3];
char data[9];
 int i =0;
/* Extern variables ----------------------------------------------------------*/
/* Private function prototypes -----------------------------------------------*/
/* Private functions ---------------------------------------------------------*/

/*******************************************************************************
* Function Name  : main.
* Description    : Main routine.
* Input          : None.
* Output         : None.
* Return         : None.
*******************************************************************************/
int main(void)
{
// data[0] = 'K';

  Set_System();
  Set_USBClock();
  USB_Interrupts_Config();
  USB_Init();
  Acc_Config();
  GyroConfig();
  while (1)
  {
   Acc_ReadData(AccData);
   GyroReadAngRate(GyroData);
   sprintf(data,"%F",AccData[0]);
   sprintf(data+3,"%F",AccData[1]);
   sprintf(data+6,"%F",AccData[2]);
    UserToPMABufferCopy((uint8_t*)data,ENDP1_TXADDR,9);
      SetEPTxCount(ENDP1, 9);
      SetEPTxValid(ENDP1); 
   sprintf(data,"%F",GyroData[0]);
   sprintf(data+3,"%F",GyroData[1]);
   sprintf(data+6,"%F",GyroData[2]);
    UserToPMABufferCopy((uint8_t*)data,ENDP1_TXADDR,9);
      SetEPTxCount(ENDP1, 9);
      SetEPTxValid(ENDP1);
   
  // printf("%s\n",AccData);
  }
}
#ifdef USE_FULL_ASSERT
/*******************************************************************************
* Function Name  : assert_failed
* Description    : Reports the name of the source file and the source line number
*                  where the assert_param error has occurred.
* Input          : - file: pointer to the source file name
*                  - line: assert_param error line source number
* Output         : None
* Return         : None
*******************************************************************************/
void assert_failed(uint8_t* file, uint32_t line)
{
  /* User can add his own implementation to report the file name and line number,
     ex: printf("Wrong parameters value: file %s on line %d\r\n", file, line) */

  /* Infinite loop */
  while (1)
  {}
}
#endif

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