RIOT/drivers/tcs37727/tcs37727.c

/*
 * Copyright (C) 2015 PHYTEC Messtechnik GmbH
 *
 * This file is subject to the terms and conditions of the GNU Lesser
 * General Public License v2.1. See the file LICENSE in the top level
 * directory for more details.
 *
 */

/**
 * @ingroup     drivers_tcs37727
 * @{
 *
 * @file
 * @brief       Driver for the AMS TCS37727 Color Light-To-Digital Converter
 *
 * @author      Felix Siebel <f.siebel@phytec.de>
 * @author      Johann Fischer <j.fischer@phytec.de>
 *
 * @}
 */

#include <stdint.h>
#include <stdbool.h>
#include "periph/i2c.h"
#include "tcs37727.h"
#include "tcs37727-internal.h"

#define ENABLE_DEBUG   (0)
#include "debug.h"

#define I2C_SPEED      I2C_SPEED_FAST

static int tcs37727_test(tcs37727_t *dev)
{
    char id;

    i2c_acquire(dev->i2c);

    if (i2c_read_reg(dev->i2c, dev->addr, TCS37727_ID, &id) != 1) {
        i2c_release(dev->i2c);
        return -1;
    }

    i2c_release(dev->i2c);

    if (id != TCS37727_ID_VALUE) {
        return -1;
    }

    return 0;
}

int tcs37727_init(tcs37727_t *dev, i2c_t i2c, uint8_t address, int atime_us)
{
    /* write device descriptor */
    dev->i2c = i2c;
    dev->addr = address;
    dev->initialized = false;

    i2c_acquire(dev->i2c);

    /* initialize the I2C bus */
    if (i2c_init_master(i2c, I2C_SPEED) < 0) {
        i2c_release(dev->i2c);
        return -1;
    }

    i2c_release(dev->i2c);

    if (tcs37727_test(dev)) {
        return -2;
    }

    i2c_acquire(dev->i2c);

    if (i2c_write_reg(dev->i2c, dev->addr, TCS37727_CONTROL,
                      TCS37727_CONTROL_AGAIN_4) != 1) {
        i2c_release(dev->i2c);
        return -3;
    }
    dev->again = 4;

    if (i2c_write_reg(dev->i2c, dev->addr, TCS37727_ATIME,
                      TCS37727_ATIME_TO_REG(atime_us)) != 1) {
        i2c_release(dev->i2c);
        return -3;
    }
    dev->atime_us = atime_us;

    dev->initialized = true;

    i2c_release(dev->i2c);
    return 0;
}

int tcs37727_set_rgbc_active(tcs37727_t *dev)
{
    uint8_t reg;

    if (dev->initialized == false) {
        return -1;
    }

    i2c_acquire(dev->i2c);
    if (i2c_read_regs(dev->i2c, dev->addr, TCS37727_ENABLE, (char *)&reg, 1) != 1) {
        i2c_release(dev->i2c);
        return -1;
    }

    reg |= (TCS37727_ENABLE_AEN | TCS37727_ENABLE_PON);

    if (i2c_write_reg(dev->i2c, dev->addr, TCS37727_ENABLE, reg) != 1) {
        i2c_release(dev->i2c);
        return -1;
    }

    i2c_release(dev->i2c);
    return 0;
}

int tcs37727_set_rgbc_standby(tcs37727_t *dev)
{
    uint8_t reg;

    if (dev->initialized == false) {
        return -1;
    }

    i2c_acquire(dev->i2c);
    if (i2c_read_regs(dev->i2c, dev->addr, TCS37727_ENABLE, (char *)&reg, 1) != 1) {
        i2c_release(dev->i2c);
        return -1;
    }

    reg &= ~TCS37727_ENABLE_AEN;
    if (!(reg & TCS37727_ENABLE_PEN)) {
        reg &= ~TCS37727_ENABLE_PON;
    }

    if (i2c_write_reg(dev->i2c, dev->addr, TCS37727_ENABLE, reg) != 1) {
        i2c_release(dev->i2c);
        return -1;
    }

    i2c_release(dev->i2c);
    return 0;
}

static uint8_t tcs37727_trim_gain(tcs37727_t *dev, int rawc)
{
    uint8_t reg_again = 0;
    int val_again = dev->again;

    if (dev->initialized == false) {
        return -1;
    }

    if (rawc < TCS37727_AG_THRESHOLD_LOW) {
        switch (val_again) {
            case 1:
                reg_again = TCS37727_CONTROL_AGAIN_4;
                val_again = 4;
                break;

            case 4:
                reg_again = TCS37727_CONTROL_AGAIN_16;
                val_again = 16;
                break;

            case 16:
                reg_again = TCS37727_CONTROL_AGAIN_60;
                val_again = 60;
                break;

            case 60:
            default:
                return -1;
        }
    }
    else if (rawc > TCS37727_AG_THRESHOLD_HIGH) {
        switch (val_again) {
            case 60:
                reg_again = TCS37727_CONTROL_AGAIN_16;
                val_again = 16;
                break;

            case 16:
                reg_again = TCS37727_CONTROL_AGAIN_4;
                val_again = 4;
                break;

            case 4:
                reg_again = TCS37727_CONTROL_AGAIN_1;
                val_again = 1;
                break;

            case 1:
            default:
                return -1;
        }
    }
    else {
        return 0;
    }

    i2c_acquire(dev->i2c);
    uint8_t reg = 0;
    if (i2c_read_reg(dev->i2c, dev->addr, TCS37727_CONTROL, (char *)&reg) != 1) {
        i2c_release(dev->i2c);
        return -2;
    }
    reg &= ~TCS37727_CONTROL_AGAIN_MASK;
    reg |= reg_again;
    if (i2c_write_reg(dev->i2c, dev->addr, TCS37727_CONTROL, reg) != 1) {
        i2c_release(dev->i2c);
        return -2;
    }
    i2c_release(dev->i2c);
    dev->again = val_again;

    return 0;
}

int tcs37727_read(tcs37727_t *dev, tcs37727_data_t *data)
{
    char buf[8];

    if (dev->initialized == false) {
        return -1;
    }

    i2c_acquire(dev->i2c);

    if (i2c_read_regs(dev->i2c, dev->addr,
                      (TCS37727_INC_TRANS | TCS37727_CDATA), buf, 8) != 8) {
        i2c_release(dev->i2c);
        return -1;
    }

    i2c_release(dev->i2c);

    int32_t tmpc = ((uint16_t)buf[1] << 8) | buf[0];
    int32_t tmpr = ((uint16_t)buf[3] << 8) | buf[2];
    int32_t tmpg = ((uint16_t)buf[5] << 8) | buf[4];
    int32_t tmpb = ((uint16_t)buf[7] << 8) | buf[6];
    DEBUG("rawr: %"PRIi32" rawg %"PRIi32" rawb %"PRIi32" rawc %"PRIi32"\n",
          tmpr, tmpg, tmpb, tmpc);

    /* Remove IR component as described in the DN40.  */
    int32_t ir = (tmpr + tmpg + tmpb - tmpc) >> 1;
    tmpr -= ir;
    tmpg -= ir;
    tmpb -= ir;

    /* Color temperature calculation as described in the DN40. */
    int32_t ct = (CT_COEF_IF * tmpb) / tmpr + CT_OFFSET_IF;

    /* Lux calculation as described in the DN40.  */
    int32_t gi = R_COEF_IF * tmpr + G_COEF_IF * tmpg + B_COEF_IF * tmpb;
    /* TODO: add Glass Attenuation Factor GA compensation */
    int32_t cpl = (dev->atime_us * dev->again) / DGF_IF;
    int32_t lux = gi / cpl;

    /* Autogain */
    tcs37727_trim_gain(dev, tmpc);

    data->red = (tmpr < 0) ? 0 : (tmpr * 1000) / cpl;
    data->green = (tmpg < 0) ? 0 : (tmpg * 1000) / cpl;
    data->blue = (tmpb < 0) ? 0 : (tmpb * 1000) / cpl;
    data->clear = (tmpb < 0) ? 0 : (tmpc * 1000) / cpl;
    data->lux = (lux < 0) ? 0 : lux;
    data->ct = (ct < 0) ? 0 : ct;

    return 0;
}