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Show/hide line numbers MAX44009.cpp Source File

MAX44009.cpp

00001 /*******************************************************************************
00002 * Copyright (C) 2016 Maxim Integrated Products, Inc., All Rights Reserved.
00003 *
00004 * Permission is hereby granted, free of charge, to any person obtaining a
00005 * copy of this software and associated documentation files (the "Software"),
00006 * to deal in the Software without restriction, including without limitation
00007 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
00008 * and/or sell copies of the Software, and to permit persons to whom the
00009 * Software is furnished to do so, subject to the following conditions:
00010 *
00011 * The above copyright notice and this permission notice shall be included
00012 * in all copies or substantial portions of the Software.
00013 *
00014 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
00015 * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
00016 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
00017 * IN NO EVENT SHALL MAXIM INTEGRATED BE LIABLE FOR ANY CLAIM, DAMAGES
00018 * OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
00019 * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
00020 * OTHER DEALINGS IN THE SOFTWARE.
00021 *
00022 * Except as contained in this notice, the name of Maxim Integrated
00023 * Products, Inc. shall not be used except as stated in the Maxim Integrated
00024 * Products, Inc. Branding Policy.
00025 *
00026 * The mere transfer of this software does not imply any licenses
00027 * of trade secrets, proprietary technology, copyrights, patents,
00028 * trademarks, maskwork rights, or any other form of intellectual
00029 * property whatsoever. Maxim Integrated Products, Inc. retains all
00030 * ownership rights.
00031 *******************************************************************************/
00032 
00033 #include <I2C.h>
00034 #include "MAX44009.hpp"
00035 
00036 static const int I2C_OK = 0;
00037 
00038 MAX44009::MAX44009 (mbed::I2C & I2C_interface, uint8_t I2C_address)
00039     : m_I2C_interface(I2C_interface), m_I2C_address(I2C_address) {}
00040 
00041 MAX44009::Result MAX44009::read_current_lux(double & lux) const {
00042   uint8_t I2C_data, mantissa, exponent;
00043 
00044   I2C_data = Lux_High_Byte_Reg;
00045   if (m_I2C_interface.write(m_I2C_address, reinterpret_cast<char *>(&I2C_data),
00046                             1, true) != I2C_OK) {
00047     m_I2C_interface.stop();
00048     return Hardware_Failure;
00049   }
00050   if (m_I2C_interface.read(m_I2C_address, reinterpret_cast<char *>(&I2C_data),
00051                            1, true) != I2C_OK) {
00052     m_I2C_interface.stop();
00053     return Hardware_Failure;
00054   }
00055   mantissa = (I2C_data << 4);
00056   exponent = (I2C_data >> 4);
00057 
00058   I2C_data = Lux_Low_Byte_Reg;
00059   if (m_I2C_interface.write(m_I2C_address, reinterpret_cast<char *>(&I2C_data),
00060                             1, true) != I2C_OK) {
00061     m_I2C_interface.stop();
00062     return Hardware_Failure;
00063   }
00064   if (m_I2C_interface.read(m_I2C_address, reinterpret_cast<char *>(&I2C_data),
00065                            1, false) != I2C_OK) {
00066     m_I2C_interface.stop();
00067     return Hardware_Failure;
00068   }
00069   mantissa |= (I2C_data & 0x0F);
00070 
00071   unsigned long calc_result = 1;
00072   if (exponent > 0) {
00073     calc_result <<= exponent;
00074   }
00075   calc_result *= mantissa;
00076   lux = calc_result * 0.045;
00077 
00078   return Success;
00079 }