File content as of revision 0:3bffc1862262:

#include "ENGO333_MMA7660.h"

const float GRAVITY = 9.8086;

ENGO333_MMA7660::ENGO333_MMA7660() : i2c(p28, p27)
{
    SetActiveMode();
    SetSamplingRateAM(MMA7660_AMSR8);
    measAccel[0] = measAccel[1] = measAccel[2] = 0;
}

bool ENGO333_MMA7660::TestConnection() 
{
    char data[3] = {128, 128, 128};
    bool alert;

    // Check data validity
    alert = false;
    i2c.readBytes(MMA7660_ADDRESS, MMA7660_XOUT_REG, data, 3);
    for (int i = 0; i < 3; ++i) {
        if (data[i] > 63)
            alert = true;
    }
    
    if (alert == false) {
        return true;
    } else {
        return false;
    }
}

void ENGO333_MMA7660::SetActiveMode()
{
    i2c.writeOneByte(MMA7660_ADDRESS, MMA7660_MODE_REG, 0x01);
}

void ENGO333_MMA7660::SetSamplingRateAM(MMA7660_AMSR_t samplingRate)
{
    char oldValue, newValue;
    oldValue = i2c.readOneByte(MMA7660_ADDRESS, MMA7660_SR_REG);
    oldValue = oldValue & 0x07;
    newValue = oldValue | samplingRate;
    i2c.writeOneByte(MMA7660_ADDRESS, MMA7660_SR_REG, newValue);
}

void ENGO333_MMA7660::ReadAccelerometers()
{
    char data[3];
    bool alert;

    // Check data validity
    do {
        alert = false;
        i2c.readBytes(MMA7660_ADDRESS, MMA7660_XOUT_REG, data, 3);
        for (int i = 0; i < 3; ++i) {
            if (data[i] > 63)
                alert = true;
            if (data[i] > 31)
                data[i] += 128 + 64;
        }
    } while (alert);
    
    measAccel[0] = (signed char)(data[0]) / MMA7660_SCALE * GRAVITY;
    measAccel[1] = (signed char)(data[1]) / MMA7660_SCALE * GRAVITY;
    measAccel[2] = (signed char)(data[2]) / MMA7660_SCALE * GRAVITY;
}

float ENGO333_MMA7660::GetAccelX() const
{
    return measAccel[0];
}

float ENGO333_MMA7660::GetAccelY() const
{
    return measAccel[1];
}

float ENGO333_MMA7660::GetAccelZ() const
{
    return measAccel[2];
}