127 lines
3.9 KiB
C
127 lines
3.9 KiB
C
/*
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* Copyright (c) 2005, Swedish Institute of Computer Science
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. Neither the name of the Institute nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* This file is part of the Contiki operating system.
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*
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* @(#)$Id: light.c,v 1.1 2006/08/02 14:44:46 bg- Exp $
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*/
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#include "contiki.h"
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#include "dev/light.h"
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#include <stdlib.h>
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/*
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* Initialize periodic readings from the 2 photo diodes. The most
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* recent readings will be stored in ADC internal registers/memory.
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*/
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void
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sensors_light_init(void)
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{
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P6SEL |= 0x30;
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P6DIR = 0xff;
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P6OUT = 0x00;
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/* Set up the ADC. */
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ADC12CTL0 = REF2_5V + SHT0_6 + SHT1_6 + MSC; // Setup ADC12, ref., sampling time
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ADC12CTL1 = SHP + CONSEQ_3 + CSTARTADD_0; // Use sampling timer, repeat-sequenc-of-channels
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ADC12MCTL0 = (INCH_4 + SREF_0); // photodiode 1 (P64)
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ADC12MCTL1 = (INCH_5 + SREF_0); // photodiode 2 (P65)
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ADC12CTL0 |= ADC12ON + REFON;
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ADC12CTL0 |= ENC; // enable conversion
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ADC12CTL0 |= ADC12SC; // sample & convert
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}
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/* Photosynthetically Active Radiation. */
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unsigned
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sensors_light1(void)
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{
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return ADC12MEM0;
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}
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/* Total Solar Radiation. */
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unsigned
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sensors_light2(void)
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{
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return ADC12MEM1;
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}
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/*
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* Most of this information taken from
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* http://www.moteiv.com/community/Getting_Data_from_Tmote_Sky%27s_Sensors
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*
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* The Photosynthetically Active Radiation (PAR) sensor as well as the
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* Total Solar Radiation (TSR) sensor uses the 2.5V reference voltage
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* to produce the raw ADC value.
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* The voltage across each sensor is:
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*
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* VsensorPAR = ADCValuePAR/4096 * Vref (1a)
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* VsensorTSR = ADCValueTSR/4096 * Vref (1b)
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* where Vref = 2.5V
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*
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* This voltage creates a current through a resistor R=100KOhm and this
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* current has a linear relationship with the light intensity in Lux.
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* IPAR = VsensorPAR / 100,000 (2a)
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* ITSR = VsensorTSR / 100,000 (2b)
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*
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* S1087 (PAR) lx = 1e6 * IPAR * 1000 (3a)
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* S1087-01 (TSR) lx = 1e5 * ITSR * 1000 (3b)
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*
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* lxPAR = 10e9 * ADCValuePAR *(1/4096)* Vref * 10e-5 or
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* lxPAR = 3125* ADCvaluePAR / 512
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* and
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* lxTSR = 10e8 * ADCValueTSR *(1/4096)* Vref * 10e-5 or
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* lxTSR = 625* ADCvalueTSR / 1024
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*/
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#if 0
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/* Photosynthetically Active Radiation in Lux units. */
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unsigned
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sensors_light1_lux(void)
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{
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unsigned temp;
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temp = (uint32_t)ADC12MEM0;
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temp = (temp*3125)>> 9;
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return (uint16_t)(temp & 0xFFFF);
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}
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/* Total Solar Radiation in Lux units. */
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unsigned
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sensors_light2_lux(void)
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{
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unsigned temp;
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temp = (uint32_t)ADC12MEM1;
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temp = (temp*625)>> 10;
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return (uint16_t)(temp & 0xFFFF);
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}
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#endif
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