Contiki 2.6

light.c

00001 /*
00002  * Copyright (c) 2011, Zolertia(TM) is a trademark of Advancare,SL
00003  * All rights reserved. 
00004  *
00005  * Redistribution and use in source and binary forms, with or without 
00006  * modification, are permitted provided that the following conditions 
00007  * are met: 
00008  * 1. Redistributions of source code must retain the above copyright 
00009  *    notice, this list of conditions and the following disclaimer. 
00010  * 2. Redistributions in binary form must reproduce the above copyright 
00011  *    notice, this list of conditions and the following disclaimer in the 
00012  *    documentation and/or other materials provided with the distribution. 
00013  * 3. Neither the name of the Institute nor the names of its contributors 
00014  *    may be used to endorse or promote products derived from this software 
00015  *    without specific prior written permission. 
00016  *
00017  * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND 
00018  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 
00019  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 
00020  * ARE DISCLAIMED.  IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE 
00021  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 
00022  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 
00023  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 
00024  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 
00025  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 
00026  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 
00027  * SUCH DAMAGE. 
00028  *
00029  * This file is part of the Contiki operating system.
00030  *
00031  *
00032  * \file
00033  *      Dummy light-sensor to allow as many programs for sky to compile for Z1
00034  *
00035  * \author
00036  *      Enric M. Calvo <ecalvo@zolertia.com>, adapted from previous work 
00037  *
00038  * @(#)$Id: light.c,v 1.0 2011/02/27 ecalvo $
00039  */
00040 
00041 #include <stdlib.h>
00042 #include "contiki.h"
00043 #include "dev/light.h"
00044 
00045 /*
00046  * Initialize periodic readings from the 2 photo diodes. The most
00047  * recent readings will be stored in ADC internal registers/memory.
00048  */
00049 void
00050 sensors_light_init(void)
00051 {
00052 }
00053 
00054 /* Photosynthetically Active Radiation. */
00055 unsigned
00056 sensors_light1(void)
00057 {
00058   return 0;
00059 }
00060 
00061 /* Total Solar Radiation. */
00062 unsigned
00063 sensors_light2(void)
00064 {
00065   return 0;
00066 }
00067 
00068 /*
00069  * Most of this information taken from
00070  * http://www.moteiv.com/community/Getting_Data_from_Tmote_Sky%27s_Sensors
00071  *
00072  * The Photosynthetically Active Radiation (PAR) sensor as well as the
00073  * Total Solar Radiation (TSR) sensor uses the 2.5V reference voltage
00074  * to produce the raw ADC value.
00075 
00076  * The voltage across each sensor is:
00077  *
00078  * VsensorPAR = ADCValuePAR/4096 * Vref       (1a)
00079  * VsensorTSR = ADCValueTSR/4096 * Vref       (1b)
00080  * where Vref = 2.5V
00081  *
00082  * This voltage creates a current through a resistor R=100KOhm and this
00083  * current has a linear relationship with the light intensity in Lux.
00084  * IPAR = VsensorPAR / 100,000             (2a) 
00085  * ITSR = VsensorTSR / 100,000             (2b) 
00086  *
00087  * S1087    (PAR) lx = 1e6 * IPAR * 1000   (3a)  
00088  * S1087-01 (TSR) lx = 1e5 * ITSR * 1000   (3b)
00089  *
00090  * lxPAR = 10e9 * ADCValuePAR *(1/4096)* Vref * 10e-5  or
00091  * lxPAR = 3125* ADCvaluePAR / 512  
00092  * and 
00093  * lxTSR = 10e8 * ADCValueTSR *(1/4096)* Vref * 10e-5  or
00094  * lxTSR = 625* ADCvalueTSR / 1024  
00095 */
00096 
00097 #if 0
00098 /* Photosynthetically Active Radiation in Lux units. */
00099 unsigned
00100 sensors_light1_lux(void)
00101 {
00102   unsigned temp;
00103   temp = (uint32_t)ADC12MEM0;
00104 
00105   temp = (temp*3125)>> 9; 
00106   return (uint16_t)(temp & 0xFFFF); 
00107 }
00108 
00109 /* Total Solar Radiation in Lux units. */
00110 unsigned
00111 sensors_light2_lux(void)
00112 {
00113   unsigned temp;
00114   temp = (uint32_t)ADC12MEM1;
00115 
00116   temp = (temp*625)>> 10; 
00117   return (uint16_t)(temp & 0xFFFF); 
00118 }
00119 #endif