osd-contiki/platform/sky/dev/light.c

127 lines
3.9 KiB
C

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