drivers/sensors/adxl345/adxl345.c

   1 /**************************************************************************/
   2 /*!
   3     @file     adxl345.c
   4     @author   K. Townsend (microBuilder.eu)
   5
   6     @brief    Drivers for Analog Devices ADXL345 Accelerometer
   7
   8     @section DESCRIPTION
   9
  10     The ADXL345 is a digital accelerometer with 13-bit resolution, capable
  11     of measuring up to +/-16g.  This driver communicate using I2C.
  12
  13     @section LICENSE
  14
  15     Software License Agreement (BSD License)
  16
  17     Copyright (c) 2012, K. Townsend
  18     All rights reserved.
  19
  20     Redistribution and use in source and binary forms, with or without
  21     modification, are permitted provided that the following conditions are met:
  22     1. Redistributions of source code must retain the above copyright
  23     notice, this list of conditions and the following disclaimer.
  24     2. Redistributions in binary form must reproduce the above copyright
  25     notice, this list of conditions and the following disclaimer in the
  26     documentation and/or other materials provided with the distribution.
  27     3. Neither the name of the copyright holders nor the
  28     names of its contributors may be used to endorse or promote products
  29     derived from this software without specific prior written permission.
  30
  31     THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS ''AS IS'' AND ANY
  32     EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
  33     WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
  34     DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE FOR ANY
  35     DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
  36     (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  37     LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
  38     ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  39     (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
  40     SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  41 */
  42 /**************************************************************************/
  43 #include "adxl345.h"
  44 #include "core/systick/systick.h"
  45
  46 extern volatile uint8_t   I2CMasterBuffer[I2C_BUFSIZE];
  47 extern volatile uint8_t   I2CSlaveBuffer[I2C_BUFSIZE];
  48 extern volatile uint32_t  I2CReadLength, I2CWriteLength;
  49
  50 static bool _adxl345Initialised = false;
  51
  52 /**************************************************************************/
  53 /*!
  54     @brief  Sends a single command byte over I2C
  55 */
  56 /**************************************************************************/
  57 static adxl345Error_t adxl345Write8 (uint8_t reg, uint8_t value)
  58 {
  59   adxl345Error_t error = ADXL345_ERROR_OK;
  60
  61   // Clear write buffers
  62   uint32_t i;
  63   for ( i = 0; i < I2C_BUFSIZE; i++ )
  64   {
  65     I2CMasterBuffer[i] = 0x00;
  66   }
  67
  68   I2CWriteLength = 3;
  69   I2CReadLength = 0;
  70   I2CMasterBuffer[0] = ADXL345_ADDRESS;       // I2C device address
  71   I2CMasterBuffer[1] = reg;                   // Register
  72   I2CMasterBuffer[2] = value;
  73   i2cEngine();
  74
  75   // ToDo: Add in proper I2C error-checking
  76   return error;
  77 }
  78
  79 /**************************************************************************/
  80 /*!
  81     @brief  Reads a 16 bit values over I2C
  82 */
  83 /**************************************************************************/
  84 static adxl345Error_t adxl345Read8(uint8_t reg, uint8_t *value)
  85 {
  86   adxl345Error_t error = ADXL345_ERROR_OK;
  87
  88   // Clear write buffers
  89   uint32_t i;
  90   for ( i = 0; i < I2C_BUFSIZE; i++ )
  91   {
  92     I2CMasterBuffer[i] = 0x00;
  93   }
  94
  95   I2CWriteLength = 2;
  96   I2CReadLength = 1;
  97   I2CMasterBuffer[0] = ADXL345_ADDRESS;         // I2C device address
  98   I2CMasterBuffer[1] = reg;                     // Command register
  99   // Append address w/read bit
 100   I2CMasterBuffer[2] = ADXL345_ADDRESS | ADXL345_READBIT;
 101   i2cEngine();
 102
 103   // Shift values to create properly formed integer
 104   *value = I2CSlaveBuffer[0];
 105
 106   // ToDo: Add in proper I2C error-checking
 107   return error;
 108 }
 109
 110 /**************************************************************************/
 111 /*!
 112     @brief  Read the device ID (can be used to check connection)
 113 */
 114 /**************************************************************************/
 115 adxl345Error_t adxl345GetDeviceID(uint8_t *id)
 116 {
 117   adxl345Error_t error = ADXL345_ERROR_OK;
 118
 119   // Check device ID register
 120   error = adxl345Read8(ADXL345_REG_DEVID, id);
 121   return error;
 122 }
 123
 124 /**************************************************************************/
 125 /*!
 126     @brief  Initialises the I2C block
 127 */
 128 /**************************************************************************/
 129 adxl345Error_t adxl345Init(void)
 130 {
 131   uint8_t devid = 0x00;
 132   adxl345Error_t error = ADXL345_ERROR_OK;
 133
 134   // Initialise I2C
 135   if (i2cInit(I2CMASTER) == false)
 136   {
 137     return ADXL345_ERROR_I2CINIT;    /* Fatal error */
 138   }
 139
 140   // Check device ID register to see if everything is properly connected
 141   error = adxl345Read8(ADXL345_REG_DEVID, &devid);
 142   if (error)
 143   {
 144     return error;
 145   }
 146   else if (devid != 0xE5)
 147   {
 148     return ADXL345_ERROR_NOCONNECTION;
 149   }
 150
 151   // Enable measurements
 152   error = adxl345Write8(ADXL345_REG_POWER_CTL, 0x08);
 153   if (error)
 154   {
 155     return error;
 156   }
 157
 158   _adxl345Initialised = true;
 159   return error;
 160 }
 161
 162 /**************************************************************************/
 163 /*!
 164     @brief  Gets the latest X/Y/Z values
 165 */
 166 /**************************************************************************/
 167 adxl345Error_t adxl345GetXYZ(int16_t *x, int16_t *y, int16_t *z)
 168 {
 169   adxl345Error_t error = ADXL345_ERROR_OK;
 170
 171   // Clear write buffers
 172   uint32_t i;
 173   for ( i = 0; i < I2C_BUFSIZE; i++ )
 174   {
 175     I2CMasterBuffer[i] = 0x00;
 176   }
 177
 178   I2CWriteLength = 2;
 179   I2CReadLength = 6;
 180   I2CMasterBuffer[0] = ADXL345_ADDRESS;         // I2C device address
 181   I2CMasterBuffer[1] = ADXL345_REG_DATAX0;
 182   // Append address w/read bit
 183   I2CMasterBuffer[2] = ADXL345_ADDRESS | ADXL345_READBIT;
 184   i2cEngine();
 185
 186   // Shift values to create properly formed integer
 187   *x = (I2CSlaveBuffer[1] << 8) | (I2CSlaveBuffer[0]);
 188   *y = (I2CSlaveBuffer[3] << 8) | (I2CSlaveBuffer[2]);
 189   *z = (I2CSlaveBuffer[5] << 8) | (I2CSlaveBuffer[4]);
 190
 191   // ToDo: Add in proper I2C error-checking
 192   return error;
 193 }
 194