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

}