File content as of revision 1:4a02a8fbf021:

/*
 * mbed library program
 *  light intensity sensor module with built-in a 16 bit AD converter generating digital signal.
 *  BH1750 by ROHM Co.,Ltd.
 *
 * Copyright (c) 2015,'17 Kenji Arai / JH1PJL
 *  http://www.page.sannet.ne.jp/kenjia/index.html
 *  http://mbed.org/users/kenjiArai/
 *      Created: March       7th, 2015
 *      Revised: August     23rd, 2017
 */

#include "BH1750.h"

BH1750::BH1750 (PinName p_sda, PinName p_scl)
 : _i2c_p(new I2C(p_sda, p_scl)), _i2c(*_i2c_p)
{
    BH1750_addr = BH1750_G_CHIP_ADDR;
    init();
}

BH1750::BH1750 (PinName p_sda, PinName p_scl, uint8_t addr)
 : _i2c_p(new I2C(p_sda, p_scl)), _i2c(*_i2c_p)
{
    BH1750_addr = addr;
    init();
}

BH1750::BH1750 (I2C& p_i2c)
 : _i2c(p_i2c)
{
    BH1750_addr = BH1750_G_CHIP_ADDR;
    init();
}

BH1750::BH1750 (I2C& p_i2c, uint8_t addr)
 : _i2c(p_i2c)
{
    BH1750_addr = addr;
    init();
}

/////////////// Read Lux from sensor //////////////////////
float BH1750::lux()
{
    float lux;

    _i2c.read(BH1750_addr, (char *)dt, 2, false);
    lux = (float)(dt[0] << 8 | dt[1]);
    lux = lux / 1.2f * ((float)sensitivity/69);
    return lux;
}

/////////////// Initialize ////////////////////////////////
void BH1750::init()
{
    _i2c.frequency(100000);
    power_up();
    sensitivity = SENS_1R00;
    set_sensitivity(sensitivity);
}

/////////////// Timing Register ///////////////////////////
void BH1750::set_sensitivity(uint8_t parameter)
{
    if (parameter > SENS_3R68){
        parameter = SENS_3R68;
    } else if (parameter < SENS_0R45){
        parameter = SENS_0R45;
    }
    dt[0] = CMD_M_TIME_H | (parameter >> 5);    // Set High byte
    _i2c.write((int)BH1750_addr, (char *)dt, 1, false);
    dt[0] = CMD_M_TIME_L | (parameter & 0x1f);  // Set Low byte
    _i2c.write((int)BH1750_addr, (char *)dt, 1, false);
    dt[0] = CMD_C_H_RES_M;      // Measurement mode: High Resolution
    _i2c.write((int)BH1750_addr, (char *)dt, 1, false);
    wait_ms(240);   // need normal conversion time(120mS) x 2
}

/////////////// Power ON/OFF //////////////////////////////
void BH1750::power_up()
{
    dt[0] = CMD_PWR_UP;
    _i2c.write((int)BH1750_addr, (char *)dt, 1, false);
}

void BH1750::power_down()
{
    dt[0] = CMD_PWR_DWN;
    _i2c.write((int)BH1750_addr, (char *)dt, 1, false);
}

/////////////// I2C Freq. /////////////////////////////////
void BH1750::frequency(int hz)
{
    _i2c.frequency(hz);
}