lis3dh.c

#include <stddef.h> /* NULL */
#include <string.h> /* memset() */
#include "lis3dh.h"

/* initialise device struct and read WHO_AM_I register */
int lis3dh_init(lis3dh_t *lis3dh) {
    uint8_t result;
    int err = 0;

    if (!lis3dh) {
        return 1;
    }

    /* if init has been given, check it */
    if (lis3dh->dev.init != NULL) {
        if (lis3dh->dev.init() != 0) {
            return 1;
        }
    }

    /* check WHO_AM_I equal to 0x33 */
    err |= lis3dh->dev.read(REG_WHO_AM_I, &result, 1);
    if (result != 0x33) {
       return 1;
    }

    /* zero device struct */
    memset(&lis3dh->acc, 0, sizeof lis3dh->acc);
    memset(&lis3dh->cfg, 0, sizeof lis3dh->cfg);
    memset(&lis3dh->adc, 0, sizeof lis3dh->adc);
    memset(&lis3dh->src, 0, sizeof lis3dh->src);

    lis3dh->cfg.fifo.mode = 0xFF; /* in use if neq 0xFF */
    lis3dh->cfg.fifo.size = 32; /* default fifo size */

    lis3dh->cfg.filter.mode = 0xFF; /* in use if neq 0xFF */
    lis3dh->cfg.filter.fds = 1; /* bypass OFF by default */

    return err;
}

/* write configuration options to the device */
/* then sleep 100 ms to let it set itself up properly */
int lis3dh_configure(lis3dh_t *lis3dh) {
    uint8_t ctrl_reg1, ctrl_reg2, ctrl_reg3;
    uint8_t ctrl_reg4, ctrl_reg5, ctrl_reg6;
    uint8_t ctrl_reg0, temp_cfg_reg;
    uint8_t fifo_ctrl_reg, int1_cfg, int2_cfg;
    uint8_t int1_ths, int2_ths, int1_dur, int2_dur;
    uint8_t click_cfg, click_ths;
    uint8_t time_limit, act_ths;
    int err = 0;

    if (!lis3dh) {
        return 1;
    }

    /* the 0x07 enables Z, Y and X axis in that order */
    ctrl_reg1 = (lis3dh->cfg.rate << 4) | 0x07;
    ctrl_reg2 = 0;
    ctrl_reg3 = 0;
    ctrl_reg4 = (lis3dh->cfg.range << 4) | (lis3dh->cfg.spi3w & 1);
    ctrl_reg5 = 0;
    ctrl_reg6 = 0;
    fifo_ctrl_reg = 0;
    int1_cfg = 0;
    int2_cfg = 0;
    int1_ths = 0;
    int2_ths = 0;
    int1_dur = 0;
    int2_dur = 0;
    click_cfg = 0;
    click_ths = 0;
    time_limit = 0;
    act_ths = 0;
    ctrl_reg0 = 0;
    temp_cfg_reg = 0;

    /* set self-test bits */
    ctrl_reg4 |= (lis3dh->cfg.self_test & 0x03) << 1;

    /* determine whether to enable ADC or TEMP sensor */
    temp_cfg_reg |= (lis3dh->cfg.en_adc & 1) << 7;
    temp_cfg_reg |= (lis3dh->cfg.en_temp & 1) << 6;

    /* set time limit */
    time_limit |= (lis3dh->cfg.time_limit & 0x7F);

    act_ths |= (lis3dh->cfg.act_ths & 0x7F); 

    /* set click config register */
    click_cfg |= (lis3dh->cfg.click.xs & 1);
    click_cfg |= (lis3dh->cfg.click.xd & 1) << 1;
    click_cfg |= (lis3dh->cfg.click.ys & 1) << 2;
    click_cfg |= (lis3dh->cfg.click.yd & 1) << 3;
    click_cfg |= (lis3dh->cfg.click.zs & 1) << 4;
    click_cfg |= (lis3dh->cfg.click.zd & 1) << 5;

    /* CLICK threshold */
    click_ths |= (lis3dh->cfg.click_ths & 0x7F);
    click_ths |= (lis3dh->cfg.click.latch & 1) << 7;

    /* set interrupt registers */
    /* INT PIN 1 */
    ctrl_reg3 |= (lis3dh->cfg.pin1.click & 1) << 7;
    ctrl_reg3 |= (lis3dh->cfg.pin1.ia1 & 1) << 6;
    ctrl_reg3 |= (lis3dh->cfg.pin1.ia2 & 1) << 5;
    ctrl_reg3 |= (lis3dh->cfg.pin1.drdy_zyxda & 1) << 4;
    ctrl_reg3 |= (lis3dh->cfg.pin1.drdy_321 & 1) << 3;
    ctrl_reg3 |= (lis3dh->cfg.pin1.wtm & 1) << 2;
    ctrl_reg3 |= (lis3dh->cfg.pin1.overrun & 1) << 1;

    /* INT PIN 2 */
    ctrl_reg6 |= (lis3dh->cfg.pin2.click & 1) << 7;
    ctrl_reg6 |= (lis3dh->cfg.pin2.ia1 & 1) << 6;
    ctrl_reg6 |= (lis3dh->cfg.pin2.ia2 & 1) << 5;
    ctrl_reg6 |= (lis3dh->cfg.pin2.boot & 1) << 4;
    ctrl_reg6 |= (lis3dh->cfg.pin2.act & 1) << 3;
    ctrl_reg6 |= (lis3dh->cfg.pin2.polarity & 1) << 1;

    /* set some of CTRL_REG5 */
    ctrl_reg5 |= (lis3dh->cfg.int2.en_4d & 1);
    ctrl_reg5 |= (lis3dh->cfg.int2.latch & 1) << 1;
    ctrl_reg5 |= (lis3dh->cfg.int1.en_4d & 1) << 2;
    ctrl_reg5 |= (lis3dh->cfg.int1.latch & 1) << 3;

    /* set INT1_CFG and INT2_CFG */
    int1_cfg |= (lis3dh->cfg.int1.xl & 1);
    int1_cfg |= (lis3dh->cfg.int1.xh & 1) << 1;
    int1_cfg |= (lis3dh->cfg.int1.yl & 1) << 2;
    int1_cfg |= (lis3dh->cfg.int1.yh & 1) << 3;
    int1_cfg |= (lis3dh->cfg.int1.zl & 1) << 4;
    int1_cfg |= (lis3dh->cfg.int1.zh & 1) << 5;
    int1_cfg |= (lis3dh->cfg.int1.en_6d & 1) << 6;
    int1_cfg |= (lis3dh->cfg.int1.aoi & 1) << 7;

    int2_cfg |= (lis3dh->cfg.int2.xl & 1);
    int2_cfg |= (lis3dh->cfg.int2.xh & 1) << 1;
    int2_cfg |= (lis3dh->cfg.int2.yl & 1) << 2;
    int2_cfg |= (lis3dh->cfg.int2.yh & 1) << 3;
    int2_cfg |= (lis3dh->cfg.int2.zl & 1) << 4;
    int2_cfg |= (lis3dh->cfg.int2.zh & 1) << 5;
    int2_cfg |= (lis3dh->cfg.int2.en_6d & 1) << 6;
    int2_cfg |= (lis3dh->cfg.int2.aoi & 1) << 7;

    /* duration values */
    int1_dur = lis3dh->cfg.int1_dur & 0x7F; 
    int2_dur = lis3dh->cfg.int2_dur & 0x7F;

    /* threshold values */
    int1_ths = lis3dh->cfg.int1_ths & 0x7F; 
    int2_ths = lis3dh->cfg.int2_ths & 0x7F;

    /* set enable FIFO if a mode is set and size (watermark) is not 0 */
    if (lis3dh->cfg.fifo.mode != 0xFF && lis3dh->cfg.fifo.size != 0) {
        ctrl_reg5 |= 0x40; /* bit FIFO_EN */
        fifo_ctrl_reg |= ((lis3dh->cfg.fifo.size - 1) & 0x1F);
        fifo_ctrl_reg |= (lis3dh->cfg.fifo.mode << 6);
        fifo_ctrl_reg |= ((lis3dh->cfg.fifo.trig & 1) << 5);
    }

    /* set enable filter if mode is set */
    if (lis3dh->cfg.filter.mode != 0xFF) {
        ctrl_reg2 |= ((lis3dh->cfg.filter.mode & 0x03) << 6);
        ctrl_reg2 |= ((lis3dh->cfg.filter.cutoff & 0x03) << 4);
        ctrl_reg2 |= ((lis3dh->cfg.filter.fds & 1) << 3);
        ctrl_reg2 |= ((lis3dh->cfg.filter.click & 1) << 2);
        ctrl_reg2 |= ((lis3dh->cfg.filter.ia2 & 1) << 1);
        ctrl_reg2 |= (lis3dh->cfg.filter.ia1 & 1);
    }

    /* always set block update (BDU) */
    /* guarantees all bytes for one [x y z] set were sampled at the same time */
    ctrl_reg4 |= 0x80;

    /* set high resolution */
    if (lis3dh->cfg.mode == LIS3DH_MODE_HR) {
        ctrl_reg4 |= 0x08;
    }

    /* set LPen */
    if (lis3dh->cfg.mode == LIS3DH_MODE_LP) {
        ctrl_reg1 |= 0x08;
    }

    /* ctrl_reg0 is 0x10 | (SDO << 7) */
    ctrl_reg0 |= 0x10;
    ctrl_reg0 |= (lis3dh->cfg.sdo_pullup & 1) << 7;


    /* Registers have to be set in this order for SPI to function correctly, I think */
    err |= lis3dh->dev.write(REG_CTRL_REG4, ctrl_reg4);
    err |= lis3dh->dev.write(REG_CTRL_REG5, ctrl_reg5);
    err |= lis3dh->dev.write(REG_FIFO_CTRL_REG, fifo_ctrl_reg);
    err |= lis3dh->dev.write(REG_INT1_CFG, int1_cfg);
    err |= lis3dh->dev.write(REG_INT1_THS, int1_ths);
    err |= lis3dh->dev.write(REG_INT1_DURATION, int1_dur);
    err |= lis3dh->dev.write(REG_INT2_CFG, int2_cfg);
    err |= lis3dh->dev.write(REG_INT2_THS, int2_ths);
    err |= lis3dh->dev.write(REG_INT2_DURATION, int2_dur);
    err |= lis3dh->dev.write(REG_CLICK_CFG, click_cfg);
    err |= lis3dh->dev.write(REG_CLICK_THS, click_ths);
    err |= lis3dh->dev.write(REG_TIME_LIMIT, time_limit);
    err |= lis3dh->dev.write(REG_TIME_LATENCY, lis3dh->cfg.time_latency);
    err |= lis3dh->dev.write(REG_TIME_WINDOW, lis3dh->cfg.time_window);
    err |= lis3dh->dev.write(REG_ACT_THS, act_ths);
    err |= lis3dh->dev.write(REG_ACT_DUR, lis3dh->cfg.act_dur);
    err |= lis3dh->dev.write(REG_TEMP_CFG_REG, temp_cfg_reg);
    err |= lis3dh->dev.write(REG_REFERENCE, lis3dh->cfg.reference);
    err |= lis3dh->dev.write(REG_CTRL_REG6, ctrl_reg6);
    err |= lis3dh->dev.write(REG_CTRL_REG0, ctrl_reg0);
    err |= lis3dh->dev.write(REG_CTRL_REG2, ctrl_reg2);
    err |= lis3dh->dev.write(REG_CTRL_REG3, ctrl_reg3);
    err |= lis3dh->dev.write(REG_CTRL_REG1, ctrl_reg1);

    lis3dh->dev.sleep(100000); /* 100 ms */
    return err;
}

 
/* The "real size" of the i16 accelerometer axis reading depends on the power mode. */
/* shift down the 16 bit word by this amount: */
static uint8_t acc_shift(uint8_t mode) {
    switch (mode) {
        case LIS3DH_MODE_HR:     return 4;  /* i12 */
        case LIS3DH_MODE_NORMAL: return 6;  /* i10 */
        case LIS3DH_MODE_LP:     return 8;  /* i8 */
        default:                 return 0;
    }
}

/* returns a scalar that when multiplied with axis reading */
/* turns it to a multiple of mg (1/1000 g). */
static uint8_t acc_sensitivity(uint8_t mode, uint8_t range) {
    switch (range) {
        case LIS3DH_FS_2G:    return (mode == LIS3DH_MODE_LP) ? 16  : (mode == LIS3DH_MODE_NORMAL) ? 4  : 1;
        case LIS3DH_FS_4G:    return (mode == LIS3DH_MODE_LP) ? 32  : (mode == LIS3DH_MODE_NORMAL) ? 8  : 2;
        case LIS3DH_FS_8G:    return (mode == LIS3DH_MODE_LP) ? 64  : (mode == LIS3DH_MODE_NORMAL) ? 16 : 4;
        case LIS3DH_FS_16G:   return (mode == LIS3DH_MODE_LP) ? 192 : (mode == LIS3DH_MODE_NORMAL) ? 48 : 12;
        default:              return 0;
    }
}

/* read a single [x y z] set. */
int lis3dh_read(lis3dh_t *lis3dh) {
    uint8_t data[6];
    uint8_t shift, sens, status;
    int err = 0;

    if (!lis3dh) {
        return 1;
    }

    shift = acc_shift(lis3dh->cfg.mode);
    sens = acc_sensitivity(lis3dh->cfg.mode, lis3dh->cfg.range);

    /* poll STATUS_REG until new data is available */

    do {
        err |= lis3dh->dev.read(REG_STATUS_REG, &status, 1);
        lis3dh->dev.sleep(1000);
    } while ((!LIS3DH_STATUS_ZYXDA(status) || !LIS3DH_STATUS_ZYXOR(status)) && !err);

    err |= lis3dh->dev.read(REG_OUT_X_L, data, 6);
    lis3dh->acc.x = (int16_t)((int16_t)(data[1] | data[0] << 8) >> shift) * sens;
    lis3dh->acc.y = (int16_t)((int16_t)(data[3] | data[2] << 8) >> shift) * sens;
    lis3dh->acc.z = (int16_t)((int16_t)(data[5] | data[4] << 8) >> shift) * sens;

    return err;
}

/* assume fifo has been configured */
/* wait until FIFO is NOT empty, then */
/* read groups of the 6 OUT bytes until EMPTY flag in FIFO_SRC is set */
int lis3dh_read_fifo(lis3dh_t *lis3dh, struct lis3dh_fifo_data *fifo) {
    uint8_t data[6]; 
    uint8_t sens, fifo_src, idx = 0;
    int err = 0;

    if (!lis3dh || !fifo) {
        return 1;
    }

    /* wait until there is at least 1 unread sample in the FIFO */

    do {
        err |= lis3dh->dev.read(REG_FIFO_SRC_REG, &fifo_src, 1);
        lis3dh->dev.sleep(1000);
    } while (!LIS3DH_FIFO_SRC_UNREAD(fifo_src) && !err);

    /* FIFO is always 10-bit / normal mode */
    sens = acc_sensitivity(LIS3DH_MODE_NORMAL, lis3dh->cfg.range);

    do {
        err |= lis3dh->dev.read(REG_OUT_X_L, data, 6);
        err |= lis3dh->dev.read(REG_FIFO_SRC_REG, &fifo_src, 1);
        fifo->x[idx] = ((int16_t)(data[1] | data[0] << 8) >> 6) * sens;
        fifo->y[idx] = ((int16_t)(data[3] | data[2] << 8) >> 6) * sens;
        fifo->z[idx] = ((int16_t)(data[5] | data[4] << 8) >> 6) * sens;
    } while (idx++ < lis3dh->cfg.fifo.size - 1 && !LIS3DH_FIFO_SRC_EMPTY(fifo_src) && !err);

    /* the device stores FIFO offsets rather than `size' so a size-32 FIFO */
    /* has an offset of 31 ^ */
    fifo->size = idx;

    return err;
}

/* if NULL, this function doesn't have to be called */
int lis3dh_deinit(lis3dh_t *lis3dh) {
    
    if (!lis3dh) {
        return 1;
    }

    if (lis3dh->dev.deinit != NULL) {
        return lis3dh->dev.deinit();
    }

    return 0;
}

/* read INT1_SRC to clear interrupt active flag and get relevant data */
int lis3dh_read_int1(lis3dh_t *lis3dh) {
    if (!lis3dh) {
        return 1;
    }
    
    return lis3dh->dev.read(REG_INT1_SRC, &lis3dh->src.int1, 1);
}

/* read INT2_SRC to clear interrupt active flag and get relevant data */
int lis3dh_read_int2(lis3dh_t *lis3dh) {
    if (!lis3dh) {
        return 1;
    }
    
    return lis3dh->dev.read(REG_INT2_SRC, &lis3dh->src.int2, 1);
}

/* read CLICK_SRC to clear interrupt active flag and get relevant data */
int lis3dh_read_click(lis3dh_t *lis3dh) {
    if (!lis3dh) {
        return 1;
    }
    
    return lis3dh->dev.read(REG_CLICK_SRC, &lis3dh->src.click, 1);
}

/* read REFERENCE reg to reset HP filter in REFERENCE mode */
/* it then uses the --current-- acceleration as the base in the filter */
int lis3dh_reference(lis3dh_t *lis3dh) {
    uint8_t res;

    if (!lis3dh) {
        return 1;
    }

    return lis3dh->dev.read(REG_REFERENCE, &res, 1);
}

/* reset user regs and reload trim params */
int lis3dh_reset(lis3dh_t *lis3dh) {
    int err = 0;

    if (!lis3dh) {
        return 1;
    }

    /* set BOOT bit so device reloads internal trim parameters */
    err |= lis3dh->dev.write(REG_CTRL_REG5, 0x80);

    /* wait 30 ms */
    lis3dh->dev.sleep(30000);

    /* write default values to rw regs */
    err |= lis3dh->dev.write(REG_CTRL_REG0, 0x10);
    err |= lis3dh->dev.write(REG_CTRL_REG1, 0x07);
    err |= lis3dh->dev.write(REG_CTRL_REG2, 0x00);
    err |= lis3dh->dev.write(REG_CTRL_REG3, 0x00);
    err |= lis3dh->dev.write(REG_CTRL_REG4, 0x00);
    err |= lis3dh->dev.write(REG_CTRL_REG5, 0x00);
    err |= lis3dh->dev.write(REG_CTRL_REG6, 0x00);
    err |= lis3dh->dev.write(REG_FIFO_CTRL_REG, 0x00);
    err |= lis3dh->dev.write(REG_INT1_CFG, 0x00);
    err |= lis3dh->dev.write(REG_INT1_THS, 0x00);
    err |= lis3dh->dev.write(REG_INT1_DURATION, 0x00);
    err |= lis3dh->dev.write(REG_INT2_CFG, 0x00);
    err |= lis3dh->dev.write(REG_INT2_THS, 0x00);
    err |= lis3dh->dev.write(REG_INT2_DURATION, 0x00);
    err |= lis3dh->dev.write(REG_CLICK_CFG, 0x00);
    err |= lis3dh->dev.write(REG_CLICK_THS, 0x00);
    err |= lis3dh->dev.write(REG_TIME_LIMIT, 0x00);
    err |= lis3dh->dev.write(REG_TIME_LATENCY, 0x00);
    err |= lis3dh->dev.write(REG_TIME_WINDOW, 0x00);
    err |= lis3dh->dev.write(REG_ACT_THS, 0x00);
    err |= lis3dh->dev.write(REG_ACT_DUR, 0x00);

    /* set BOOT bit again so device reloads internal trim parameters */
    err |= lis3dh->dev.write(REG_CTRL_REG5, 0x80);

    /* wait 30 ms */
    lis3dh->dev.sleep(30000);
    
    return err;
}

/* read all 3 ADCs and convert data depending on power mode */
/* result: 1 lsb is equal to 1 millivolt */
int lis3dh_read_adc(lis3dh_t *lis3dh) {
    uint8_t data[6];
    uint8_t shift;
    int err = 0;

    if (!lis3dh) {
        return 1;
    }

    err |= lis3dh->dev.read(REG_OUT_ADC1_L, data, 6);

    shift = (lis3dh->cfg.mode == LIS3DH_MODE_LP) ? 8 : 6;

    lis3dh->adc.adc1 = (int16_t)(1200 + ((800 * ((int16_t)(data[1] | data[0] << 8) >> shift)) >> (16 - shift)));
    lis3dh->adc.adc2 = (int16_t)(1200 + ((800 * ((int16_t)(data[3] | data[2] << 8) >> shift)) >> (16 - shift))); 
    lis3dh->adc.adc3 = (int16_t)(1200 + ((800 * ((int16_t)(data[5] | data[4] << 8) >> shift)) >> (16 - shift))); 

    return err;
}

/* the temperature sensor only reports the difference between its current temp, */
/* and the factory calibrated temperature, 25 celsius. */
/* in increments of plus or negative 1 unit celsius. */
/* the reported temperature is stored inplace of adc3 */
/* temp sensing is always in 8-bit mode */
/* operating range: -40 to 85 celsius */
/* 1 lsb = 1 deg C */
int lis3dh_read_temp(lis3dh_t *lis3dh) {
    uint8_t data;
    int err = 0;

    if (!lis3dh) {
        return 1;
    }

    err |= lis3dh->dev.read(REG_OUT_ADC3_H, &data, 1);
    lis3dh->adc.adc3 = (int8_t)data + 25;
    return err;
}

/* This function is meant to be used to reset the FIFO in `FIFO' mode. */
int lis3dh_fifo_reset(lis3dh_t *lis3dh) {
    int err = 0;
    uint8_t fifo_ctrl_reg = 0;

    if (!lis3dh) {
        return 1;
    }

    /* create a FIFO_MODE_BYPASS config */
    fifo_ctrl_reg |= ((lis3dh->cfg.fifo.size - 1) & 0x1F);
    fifo_ctrl_reg |= (LIS3DH_FIFO_MODE_BYPASS << 6);
    fifo_ctrl_reg |= ((lis3dh->cfg.fifo.trig & 1) << 5);

    /* write it to the device */
    err |= lis3dh->dev.write(REG_FIFO_CTRL_REG, fifo_ctrl_reg);
    lis3dh->dev.sleep(1000);

    /* re-create original FIFO mode config */
    fifo_ctrl_reg |= (lis3dh->cfg.fifo.mode << 6);

    /* write to device to immediately start FIFO sampling process */
    err |= lis3dh->dev.write(REG_FIFO_CTRL_REG, fifo_ctrl_reg);

    return err;

}