1 #include "adxl345.h"

     2 

     3 #include "spi.h"

     4 

     5 #include <util/delay.h>

     6 

     7 /*

     8  * SPI format

     9  */

    10 enum adxl345_header_bits {

    11     ADXL345_READ        = 0b10000000,

    12     ADXL345_WRITE       = 0b00000000,

    13 

    14     ADXL345_MULTI       = 0b01000000,

    15 };

    16 

    17 enum adxl345_reg {

    18     ADXL345_DEVID       = 0x00,

    19 

    20     ADXL345_POWER_CTL   = 0x2D,

    21 

    22     ADXL345_DATA_FORMAT = 0x31,

    23     ADXL345_DATAX0      = 0x32,

    24     ADXL345_DATAX1      = 0x33,

    25     ADXL345_DATAY0      = 0x34,

    26     ADXL345_DATAY1      = 0x35,

    27     ADXL345_DATAZ0      = 0x36,

    28     ADXL345_DATAZ1      = 0x37,

    29 };

    30 

    31 enum adxl345_power_ctl {

    32     ADXL345_POWER_CTL_LINK          = 0b00100000,

    33     ADXL345_POWER_CTL_AUTO_SLEEP    = 0b00010000,

    34     ADXL345_POWER_CTL_MEASURE       = 0b00001000,

    35     ADXL345_POWER_CTL_SLEEP         = 0b00000100,

    36     ADXL345_POWER_CTL_WAKEUP        = 0b00000011,

    37 };

    38 

    39 enum adxl345_power_ctl_wakeup {

    40     ADXL345_POWER_CTL_WAKEUP_8      = 0b00000011,

    41     ADXL345_POWER_CTL_WAKEUP_4      = 0b00000001,

    42     ADXL345_POWER_CTL_WAKEUP_2      = 0b00000010,

    43     ADXL345_POWER_CTL_WAKEUP_1      = 0b00000000,

    44 };

    45 

    46 enum adxl345_data_format {

    47     ADXL345_DATA_FORMAT_SELF_TEST   = 0b10000000,

    48     ADXL345_DATA_FORMAT_SPI         = 0b01000000,

    49     ADXL345_DATA_FORMAT_INT_INVERT  = 0b00100000,

    50     ADXL345_DATA_FORMAT_FULL_RES    = 0b00001000,

    51     ADXL345_DATA_FORMAT_JUSTIFY     = 0b00000100,

    52     ADXL345_DATA_FORMAT_RANGE       = 0b00000011,

    53 };

    54 

    55 enum adxl345_data_format_range {

    56     ADXL345_DATA_FORMAT_RANGE_2G    = 0b00000000,

    57     ADXL345_DATA_FORMAT_RANGE_4G    = 0b00000001,

    58     ADXL345_DATA_FORMAT_RANGE_8G    = 0b00000010,

    59     ADXL345_DATA_FORMAT_RANGE_16G   = 0b00000011,

    60 };

    61 

    62 #define ADXL345_DDR DDRB

    63 #define ADXL345_PORT PORTB

    64 #define ADXL345_CS PORTB2

    65 

    66 void adxl345_init ()

    67 {

    68     // set CS pin

    69     sbi(&ADXL345_DDR,    ADXL345_CS);   // out

    70     sbi(&ADXL345_PORT,   ADXL345_CS);   // high (off)

    71 }

    72 

    73 static inline void adxl345_start ()

    74 {

    75     cbi(&ADXL345_PORT,   ADXL345_CS);    // low (on)

    76     _delay_us(1);

    77 }

    78 

    79 static inline void adxl345_stop ()

    80 {

    81     sbi(&ADXL345_PORT,   ADXL345_CS);    // high (off)

    82     _delay_us(100);

    83 }

    84 

    85 static void adxl345_write (enum adxl345_reg reg, byte value)

    86 {

    87     adxl345_start();

    88 

    89     spi_readwrite(ADXL345_WRITE | reg);

    90     spi_readwrite(value);

    91 

    92     adxl345_stop();

    93 }

    94 

    95 static byte adxl345_read (enum adxl345_reg reg)

    96 {

    97     byte value;

    98 

    99     adxl345_start();

   100 

   101     spi_readwrite(ADXL345_READ | reg);

   102     value = spi_readwrite(0);

   103 

   104     adxl345_stop();

   105 

   106     return value;

   107 }

   108 

   109 static int8_t adxl345_read_s8 (enum adxl345_reg reg)

   110 {

   111     int8_t value = 0;

   112 

   113     adxl345_start();

   114 

   115     spi_readwrite(ADXL345_READ | ADXL345_MULTI | reg);

   116     value = spi_readwrite(0);

   117 

   118     adxl345_stop();

   119 

   120     return value;

   121 }

   122 

   123 static int16_t adxl345_read_s16 (enum adxl345_reg reg)

   124 {

   125     char v0, v1;

   126 

   127     adxl345_start();

   128 

   129     spi_readwrite(ADXL345_READ | ADXL345_MULTI | reg);

   130     v0 = spi_readwrite(0);

   131     v1 = spi_readwrite(0);

   132     adxl345_stop();

   133 

   134     return ((int) v1 << 8) | (int) v0;

   135 }

   136 

   137 byte adxl345_read_devid ()

   138 {

   139     return adxl345_read(ADXL345_DEVID);

   140 }

   141 

   142 void adxl345_setup ()

   143 {

   144     adxl345_write(ADXL345_POWER_CTL,

   145             // enable measrurement mode

   146             ADXL345_POWER_CTL_MEASURE

   147     );

   148 

   149     /*

   150     adxl345_write(ADXL345_DATA_FORMAT,

   151             // self-test

   152             ADXL345_DATA_FORMAT_SELF_TEST

   153     );

   154     */

   155 }

   156 

   157 int16_t adxl345_read_x ()

   158 {

   159     return adxl345_read_s16(ADXL345_DATAX0);

   160 }

   161 

   162 int16_t adxl345_read_y ()

   163 {

   164     return adxl345_read_s16(ADXL345_DATAY0);

   165 }

   166 

   167 int16_t adxl345_read_z ()

   168 {

   169     return adxl345_read_s16(ADXL345_DATAZ0);

   170 }