accelerometer.c

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//////////////////////////////////////////////////////////////////////////////////
/// \file accelerometer.c
/// \brief ARMEBS4 accelerometer access functions
/// \author Pascal Sartoretti (sap at hevs dot ch)
//////////////////////////////////////////////////////////////////////////////////
#include "heivs/accelerometer.h"
#include "heivs/stm32_i2c.h"

// address of ACCELEROMETER MMA7660FC mounted on ARMEBS4
#define ADDR_MMA7660        0x4C

#define ACC_XOUT    0x00        // 6-bit output value X - Alert XOUT[5] XOUT[4] XOUT[3] XOUT[2] XOUT[1] XOUT[0]
#define ACC_YOUT    0x01        // 6-bit output value Y - Alert YOUT[5] YOUT[4] YOUT[3] YOUT[2] YOUT[1] YOUT[0]
#define ACC_ZOUT    0x02        // 6-bit output value Z - Alert ZOUT[5] ZOUT[4] ZOUT[3] ZOUT[2] ZOUT[1] ZOUT[0]
#define ACC_TILT    0x03        // Tilt Status Shake Alert Tap PoLa[2] PoLa[1] PoLa[0] BaFro[1] BaFro[0]
#define ACC_SRST    0x04        // Sampling Rate Status 0 0 0 0 0 0 AWSRS AMSRS
#define ACC_SPCNT   0x05        // Sleep Count SC[7] SC[6] SC[5] SC[4] SC[3] SC[2] SC[1] SC[0]
#define ACC_INTSU   0x06        // Interrupt Setup SHINTX SHINTY SHINTZ GINT ASINT PDINT PLINT FBINT
#define ACC_MODE    0x07        // Mode IAH IPP SCPS ASE AWE TON - MODE
#define ACC_SR      0x08        // Auto-Wake/Sleep and Portrait/Landscape samples per seconds and Debounce Filter
                                // FILT[2] FILT[1] FILT[0] AWSR[1] AWSR[0] AMSR[2] AMSR[1] AMSR[0]
#define ACC_PDET    0x09        // Tap Detection ZDA YDA XDA PDTH[4] PDTH[3] PDTH[2] PDTH[1] PDTH[0]
#define ACC_PD      0x0A        // Tap Debounce Count PD[7] PD[6] PD[5] PD[4] PD[3] PD[2] PD[1] PD[0]

#define SIGN_BIT    0x20        // sign bit in data register
#define MASK_ERROR  0x40        // mask status read bit in data register

#define STDBY_MODE  0x00        // stanby mode for configuration
#define ACTIVE_MODE 0x01        // active mode for measure
static const struct heivs_bus_t *bus = &bus_i2c[0];

status_e Accel_Init(void)
{
    status_e status;

    status = bus_init(bus);
    if(status != NO_ERROR)
        return status;
    status = Accel_WriteCfg(ACC_MODE,STDBY_MODE);
    if(status != NO_ERROR)
        return status;
    status = Accel_WriteCfg(ACC_SR,0);
    if(status != NO_ERROR)
        return status;
    status = Accel_WriteCfg(ACC_MODE,ACTIVE_MODE);
    if(status != NO_ERROR)
        return status;
    return NO_ERROR;
}

status_e Accel_Read(struct accelerometer_data_t * accelData)
{
    status_e status;
    uint8_t regAddress = ACC_XOUT;
    uint8_t readData[3];
    uint8_t i;

    status = bus_get(bus);
    if (status != NO_ERROR) return status;

    while (1)
    {
        status = bus_writeread(bus,ADDR_MMA7660,&regAddress,1,readData,3,NULL);
        if(status != NO_ERROR) return status;

        // The measure is good when there is no alert bit set
        if (!(readData[0] & MASK_ERROR) && !(readData[1] & MASK_ERROR) && !(readData[2] & MASK_ERROR))
        {
            break;
        }
    }

    status = bus_release(bus);
    if (status != NO_ERROR) return status;

    for (i = 0 ; i < ARRAY_SIZE(readData); i++)
    {
        if (readData[i] & SIGN_BIT)
        {
            readData[i] |= 0xc0;
        }
    }
    accelData->x = readData[0];
    accelData->y = readData[1];
    accelData->z = readData[2];

    return NO_ERROR;
}

status_e Accel_WriteCfg(uint8_t reg, uint8_t data )
{
    status_e status;
    uint8_t dta[2];

    dta[0] = reg;
    dta[1] = data;
    status = bus_get(bus);
    if(status != NO_ERROR) return status;
    status = bus_write(bus,ADDR_MMA7660,&dta,2);
    if(status != NO_ERROR) return status;
    status = bus_release(bus);
    if(status != NO_ERROR) return status;

    return NO_ERROR;
}