Accelerometer sensor Grove kit

accel.c

#include "accel.h"

void AccelSetup(int bus) {
  uint8_t modeReg;

  I2cOpen(bus);
  I2cSetSlave(bus, 0x4c);

  I2cReadByte(bus, MMA7660_REG_MODE, &modeReg);
  
  modeReg &= ~MMA7660_MODE_TON;
  modeReg &= ~MMA7660_MODE_MODE;

  I2cWriteByte(bus, MMA7660_REG_MODE, modeReg);

  I2cWriteByte(bus, MMA7660_REG_SR, MMA7660_AUTOSLEEP_64);

  I2cReadByte(bus, MMA7660_REG_MODE, &modeReg);
  
  modeReg &= ~MMA7660_MODE_TON;
  modeReg |= MMA7660_MODE_MODE;
  
  I2cWriteByte(bus, MMA7660_REG_MODE, modeReg);
  
}


void AccelGetValue(int bus, float* x, float* y, float* z) {

  uint8_t valueX = 0;
  uint8_t valueY = 0;
  uint8_t valueZ = 0;
  int valueRaw;
  
  do {
    I2cReadByte(bus, MMA7660_REG_XOUT, &valueX);
  } while (valueX & 0x40); // check alert bit
  
  do {
    I2cReadByte(bus, MMA7660_REG_YOUT, &valueY);
  } while (valueY & 0x40); // check alert bit
  
  do {
    I2cReadByte(bus, MMA7660_REG_ZOUT, &valueZ);
  } while (valueZ & 0x40); // check alert bit
  
  
  // shift the sign bit over, and compensate
  // 21.33, typical counts/g
  valueRaw = ((int8_t)(valueX << 2) / 4);
  *x = valueRaw / 21.33;

  valueRaw = ((int8_t)(valueY << 2) / 4);
  *y = valueRaw / 21.33;

  valueRaw = ((int8_t)(valueZ << 2) / 4);
  *z = valueRaw / 21.33;
}

accel.h

#ifndef __HARDWARE_ACCEL_H_
#define __HARDWARE_ACCEL_H_

#include "i2c.h"
#include <unistd.h>
#include <stdint.h>

#define MMA7660_DEFAULT_I2C_BUS 1
#define MMA7660_DEFAULT_I2C_ADDR 0x4c

// MMA7660 registers
typedef enum {
  MMA7660_REG_XOUT       = 0x00,
  MMA7660_REG_YOUT       = 0x01,
  MMA7660_REG_ZOUT       = 0x02,
  MMA7660_REG_TILT       = 0x03,
  MMA7660_REG_SRST       = 0x04, // Sampling Rate Status
  MMA7660_REG_SPCNT      = 0x05, // sleep count
  MMA7660_REG_INTSU      = 0x06, // Interrupt setup
  MMA7660_REG_MODE       = 0x07, // operating mode
  MMA7660_REG_SR         = 0x08, // auto-wake/sleep, SPS, and debounce
  MMA7660_REG_PDET       = 0x09, // tap detection
  MMA7660_REG_PD         = 0x0a  // tap debounce count
  // 0x0b-0x1f reserved
} MMA7660_REG_T;

// interrupt enable register bits
typedef enum {
  MMA7660_INTR_NONE          = 0x00, // disabled
  MMA7660_INTR_FBINT         = 0x01, // front/back
  MMA7660_INTR_PLINT         = 0x02, // up/down/right/left
  MMA7660_INTR_PDINT         = 0x04, // tap detection
  MMA7660_INTR_ASINT         = 0x08, // exit auto-sleep
  MMA7660_INTR_GINT          = 0x10, // measurement intr
  MMA7660_INTR_SHINTZ        = 0x20, // shake on Z
  MMA7660_INTR_SHINTY        = 0x40, // shake on Y
  MMA7660_INTR_SHINTX        = 0x80  // shake on X
} MMA7660_INTR_T;

// operating mode register bits
typedef enum {
  MMA7660_MODE_MODE          = 0x01, // determines mode with MODE_TON
  // 0x02 reserved
  MMA7660_MODE_TON           = 0x04, // determines mode with MODE_MODE
  MMA7660_MODE_AWE           = 0x08, // auto-wake
  MMA7660_MODE_ASE           = 0x10, // auto-sleep
  MMA7660_MODE_SCPS          = 0x20, // sleep count prescale
  MMA7660_MODE_IPP           = 0x40, // intr out push-pull/open drain
  MMA7660_MODE_IAH           = 0x80  // intr active low/high
} MMA7660_MODE_T;

// tilt BackFront (BF) bits
typedef enum {
  MMA7660_BF_UNKNOWN          = 0x00,
  MMA7660_BF_LYING_FRONT      = 0x01,
  MMA7660_BF_LYING_BACK       = 0x02
} MMA7660_TILT_BF_T;

// tilt LandscapePortrait (LP) bits
typedef enum {
  MMA7660_LP_UNKNOWN          = 0x00,
  MMA7660_LP_LANDSCAPE_LEFT   = 0x01,
  MMA7660_LP_LANDSCAPE_RIGHT  = 0x02,
  MMA7660_LP_VERT_DOWN        = 0x05,
  MMA7660_LP_VERT_UP          = 0x06
} MMA7660_TILT_LP_T;

// sample rate (auto-sleep) values
typedef enum {
  MMA7660_AUTOSLEEP_120   = 0x00,
  MMA7660_AUTOSLEEP_64    = 0x01,
  MMA7660_AUTOSLEEP_32    = 0x02,
  MMA7660_AUTOSLEEP_16    = 0x03,
  MMA7660_AUTOSLEEP_8     = 0x04,
  MMA7660_AUTOSLEEP_4     = 0x05,
  MMA7660_AUTOSLEEP_2     = 0x06,
  MMA7660_AUTOSLEEP_1     = 0x07
} MMA7660_AUTOSLEEP_T;

void AccelSetup(int bus);

void AccelGetValue(int bus, float* x, float* y, float* z);

#endif