forked from luon/wordclock
Implemented dimming based on amount of ambient light.
Requires a phototranistor (TEPT4400) and series resistor (I used 2.2 kOhm) on ADC0 (pin 23). Range is quite limited though, so will probably need to modify hardware a bit and do some more software tuning.
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4380334947
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@ -362,8 +362,11 @@ all: $(OBJDIR) $(TARGET_HEX)
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$(OBJDIR):
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mkdir $(OBJDIR)
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# need to add -lm to the end of CC line for ELF target due to compiler / linker
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# bug; see
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# http://stackoverflow.com/questions/8188849/avr-linker-error-relocation-truncated-to-fit
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$(TARGET_ELF): $(OBJS)
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$(CC) $(LDFLAGS) -o $@ $(OBJS) $(SYS_OBJS)
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$(CC) $(LDFLAGS) -o $@ $(OBJS) $(SYS_OBJS) -lm
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$(DEP_FILE): $(OBJDIR) $(DEPS)
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cat $(DEPS) > $(DEP_FILE)
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@ -0,0 +1,46 @@
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function lightlevelmapping()
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MINBRIGHTNESS = 2;
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MAXBRIGHTNESS = 20;
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LIGHTSENSOR_BOTTOM = 270;
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LIGHTSENSOR_TOP = 350;
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l = [LIGHTSENSOR_BOTTOM - 10:LIGHTSENSOR_TOP + 10];
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b = zeros(size(l));
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LIGHTSENSOR_SCALE = 1024;
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LIGHTSENSOR_BASE = 1.35;
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if (LIGHTSENSOR_BASE <= 1)
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error 'LIGHTSENSOR_BASE must be > 1';
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end
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brightness_per_unit_light = floor(floor( LIGHTSENSOR_SCALE * (MAXBRIGHTNESS - MINBRIGHTNESS)) / ...
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(LIGHTSENSOR_TOP - LIGHTSENSOR_BOTTOM))
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LIGHTSENSOR_BASE^(MAXBRIGHTNESS - MINBRIGHTNESS) * (MAXBRIGHTNESS - MINBRIGHTNESS) + MINBRIGHTNESS
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% b = floor(brightness_per_unit_light * (l - LIGHTSENSOR_BOTTOM) / LIGHTSENSOR_SCALE ) + MINBRIGHTNESS;
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b1 = (LIGHTSENSOR_BASE.^(brightness_per_unit_light * (l - LIGHTSENSOR_BOTTOM) / ...
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LIGHTSENSOR_SCALE)) / LIGHTSENSOR_BASE^(MAXBRIGHTNESS - MINBRIGHTNESS) * (MAXBRIGHTNESS - ...
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MINBRIGHTNESS) + MINBRIGHTNESS;
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b = floor( (LIGHTSENSOR_BASE.^floor(brightness_per_unit_light * (l - LIGHTSENSOR_BOTTOM) / ...
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LIGHTSENSOR_SCALE)) / LIGHTSENSOR_BASE^(MAXBRIGHTNESS - MINBRIGHTNESS) * (MAXBRIGHTNESS - ...
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MINBRIGHTNESS)) + MINBRIGHTNESS;
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[brightness_per_unit_light * (l - LIGHTSENSOR_BOTTOM) / LIGHTSENSOR_SCALE; l]
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b1(l <= LIGHTSENSOR_BOTTOM) = MINBRIGHTNESS;
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b1(l >= LIGHTSENSOR_TOP) = MAXBRIGHTNESS;
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b(l <= LIGHTSENSOR_BOTTOM) = MINBRIGHTNESS;
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b(l >= LIGHTSENSOR_TOP) = MAXBRIGHTNESS;
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b2 = round(b1);
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figure
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plot(l, b1, l, b, l, b2)
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A = axis;
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A(3) = -1;
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A(4) = MAXBRIGHTNESS + 1;
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axis(A);
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grid on
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@ -3,6 +3,7 @@
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#include <DS1302.h> // I use the library that Matt Sparks created
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#include <avr/interrupt.h>
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#include <avr/io.h>
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#include <math.h>
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// uncomment the following to speed up the timer for testing
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//#define TESTMODE
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@ -61,11 +62,30 @@ void SWversion(void);
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*/
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// set USELIGHTSENSOR to 1 to use ambient light sensor connected to ADC0 (pin
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// 23)
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#define USELIGHTSENSOR 1
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// analog input put to which ambiend light sensor is connected
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#define LIGHTSENSOR_INPUTPIN 0
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// bottom of light sensor (ambient light values at or lower than this level will
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// be mapped to MINBRIGHTNESS)
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#define LIGHTSENSOR_BOTTOM 270
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// top of light sensor (ambient light values at or higher than this level will
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// be mapped to MAXBRIGHTNESS)
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#define LIGHTSENSOR_TOP 300
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// weight for exponential decaying averaging (actual weigth is 2 ^ LIGHTSENSOR_WEIGHT)
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#define LIGHTSENSOR_WEIGHT 4
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// base of exponential mapping (must be > 1)
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#define LIGHTSENSOR_BASE 1.35
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// DAY Brightness setting 0 = off 20 = full
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#define DAYBRIGHTNESS 20
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#define MAXBRIGHTNESS 20
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// start MAXBRIGHTNESS at DAYLIGHTHOUR (7 am)
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#define DAYLIGHTHOUR 7
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// NIGHT Brightness setting 0 = off 20 = full
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#define NIGHTBRIGHTNESS 15
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#define MINBRIGHTNESS 2
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// start MINBRIGHTNESS at NIGHTLIGHTHOUR (7 pm)
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#define NIGHTLIGHTHOUR 19
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@ -79,8 +99,12 @@ void SWversion(void);
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#define INIT_TIMER_COUNT 6
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#define RESET_TIMER2 TCNT2 = INIT_TIMER_COUNT
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// there are only 20 brightness levels and 1024 lightsensor levels -> we need to
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// scale the brightness levels to something closer to avoid having to work with
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// floating point numbers
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#define LIGHTSENSOR_SCALE 10
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unsigned int brightness_per_unit_light = ((1 << LIGHTSENSOR_SCALE) * (MAXBRIGHTNESS -
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MINBRIGHTNESS)) / (LIGHTSENSOR_TOP - LIGHTSENSOR_BOTTOM);
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int hour=12, minute=0, second=00;
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static unsigned long msTick =0; // the number of Millisecond Ticks since we last
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@ -115,6 +139,8 @@ int LED4PIN=16; // Arduino analog 2
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int current_brightnes=0;
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char ambient_light_to_brightness[1024];
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// define the language to be used for this project:
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#include LANGUAGE // The language pack
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@ -146,6 +172,8 @@ void print_DS1302time()
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void setup()
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{
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int n;
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// initialise the hardware
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// initialize the appropriate pins as outputs:
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pinMode(LEDClockPin, OUTPUT);
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@ -165,7 +193,9 @@ void setup()
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pinMode(LED3PIN, OUTPUT);
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pinMode(LED4PIN, OUTPUT);
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current_brightnes=DAYBRIGHTNESS;
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analogReference(DEFAULT);
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current_brightnes=MAXBRIGHTNESS;
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Serial.begin(9600); // setup the serial port to 9600 baud
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@ -202,6 +232,28 @@ void setup()
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else Serial.println("absent");
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}
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// compute ambient light level to brightness level mapping
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for (n = 0; n < sizeof(ambient_light_to_brightness); n++)
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{
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if (n <= LIGHTSENSOR_BOTTOM)
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ambient_light_to_brightness[n] = MINBRIGHTNESS;
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else if (n >= LIGHTSENSOR_TOP)
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ambient_light_to_brightness[n] = MAXBRIGHTNESS;
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else
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{
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ambient_light_to_brightness[n] =
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round( pow((double) LIGHTSENSOR_BASE, (
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(double) brightness_per_unit_light * ((double) n - (double)
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LIGHTSENSOR_BOTTOM) / (double) (1 << LIGHTSENSOR_SCALE))) / pow((double)
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LIGHTSENSOR_BASE, (double) (MAXBRIGHTNESS - (double) MINBRIGHTNESS)) *
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((double) MAXBRIGHTNESS - (double) MINBRIGHTNESS) + (double) MINBRIGHTNESS );
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/* Serial.print(n);
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Serial.print(": ");
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Serial.println(ambient_light_to_brightness[n], DEC); */
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}
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}
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// determine whether we are running on old or new hardware
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// old hardware tied the push buttons to ground using 4k7 resistors
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// and relied on the buttons to pull them high
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@ -353,6 +405,10 @@ void SWversion(void) {
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void loop(void)
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{
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static unsigned long int lightlevel_avg;
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unsigned long int lightlevel_sample;
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static char n_lightlevel_samples = 0;
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static unsigned int counter = 0;
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#ifdef TESTMODE
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second=59;
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@ -373,13 +429,6 @@ void loop(void)
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digitalWrite(13,HIGH);
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delay(50);
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digitalWrite(13,LOW);
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#ifndef TESTMODE
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if (second%5==0) {
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Serial.print(second);
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Serial.print("..");
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}
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#endif
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}
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@ -401,10 +450,56 @@ void loop(void)
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// set the brightnes level based on the current hour - night=7pm - 6.59am
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//
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if ((hour <7) | (hour >=19))
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current_brightnes=NIGHTBRIGHTNESS;
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#if (USELIGHTSENSOR == 1)
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lightlevel_sample = analogRead(LIGHTSENSOR_INPUTPIN);
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// update average
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if (n_lightlevel_samples < (1 << LIGHTSENSOR_WEIGHT))
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{
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// add (1 << (LIGHTSENSOR_WEIGHT - 1)) to average before division so that
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// the average is round()-ed instead of floor()-ed
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lightlevel_avg = (n_lightlevel_samples * lightlevel_avg +
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lightlevel_sample + (1 << (LIGHTSENSOR_WEIGHT - 1))) /
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(n_lightlevel_samples + 1);
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n_lightlevel_samples++;
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}
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else
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{
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// do not update n_lightlevel_samples to prevent overflow
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// add (1 << (LIGHTSENSOR_WEIGHT - 1)) to average before division so that
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// the average is round()-ed instead of floor()-ed
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lightlevel_avg = ( ((1 << LIGHTSENSOR_WEIGHT) - 1) * lightlevel_avg +
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lightlevel_sample + (1 << (LIGHTSENSOR_WEIGHT - 1))) >> LIGHTSENSOR_WEIGHT;
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}
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// compute new brightness level
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/*
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// linear method
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if (lightlevel_avg <= LIGHTSENSOR_BOTTOM)
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current_brightnes = MINBRIGHTNESS;
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else if (lightlevel_avg >= LIGHTSENSOR_TOP)
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current_brightnes = MAXBRIGHTNESS;
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else
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{
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current_brightnes = (brightness_per_unit_light * (lightlevel_avg -
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LIGHTSENSOR_BOTTOM)) / (1 << LIGHTSENSOR_SCALE) + MINBRIGHTNESS;
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} */
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current_brightnes = ambient_light_to_brightness[lightlevel_avg];
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Serial.print("lightsensor: ");
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Serial.print(lightlevel_sample);
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Serial.print(" / ");
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Serial.print(lightlevel_avg);
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Serial.print(", brightness: ");
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Serial.println(current_brightnes);
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#else
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if ((hour < DAYLIGHTHOUR) | (hour >= NIGHTLIGHTHOUR))
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current_brightnes=MINBRIGHTNESS;
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else
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current_brightnes=DAYBRIGHTNESS;
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current_brightnes=MAXBRIGHTNESS;
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#endif
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// test to see if both buttons are being held down
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