Update README.md

* Poll RTC by trigger, set via ISR
* Change blink state by trigger, set via ISR
* Set time compensation trigger in ISR
* Refresh clock by timer
* Re-calculate displayed time only ater rtcsync or when time adjusted by buttons
* Simplify draw algo

README.md

@@ -12,8 +12,6 @@
 * usb phone charger as power supply
 * 2 push buttons
 * 1 on/off switch
-* 1 photoresistor
-* 1 resistor to make secund shoulder of photosensitive "bridge", 10 kOhms, 0.25 watts
 * Gainta G521G enclosure (92x66.5x28мм)
 * 5m power cord
 
@@ -26,3 +24,12 @@
 ### Additional Notes:
 
 My RTC module is not very accurate due to bad quartz chrystal calibration, looks like it is not exactly 32768 Hz and clock runs faster than it should be, giving about 5-8 seconds runaway per day. So i have to implement time correction in software (temperature changes during day/month/year is not very big - about 10 degrees Celsius, so we can use software compensation without thermal compensation).
+
+This project split into 2 branches:
+
+* **default** that contains generic clock without any additional elements
+* **photoresistor** that contains additional hardware - photocell bridge - and software algorithm that compensates ambient light sensed by photocell basing on LED display charachteristics.
+
+### Stable tags for branches:
+v1.6 - default
+v1.7 - photoresistor

simpleclock.ino

@@ -11,9 +11,6 @@
 #include <DS1307.h>
 #include <SevSeg.h>
 
-#define cbi(sfr, bit) (_SFR_BYTE(sfr) &= ~_BV(bit))
-#define sbi(sfr, bit) (_SFR_BYTE(sfr) |= _BV(bit))
-
 DS1307 clock;
 SevSeg Display;
 
@@ -35,13 +32,6 @@ volatile bool compflag2 = false;
 const uint8_t timeSkew = 8;          // assume that clock runs faster than should
 volatile bool timeSkewEven = false;  // comp. 1 additional second per 2 days
 
-/* ambient light compensation aka night mode */
-const int photoPin = A2;
-volatile bool measureAmbLight = true;
-unsigned int ambLight = 0;
-unsigned long previousLightTimer = 0;
-const long refresh_interval = 40;    // refresh rate 25Hz
-
 /* time vars */
 volatile uint8_t mysecond;
 volatile uint8_t myminute;
@@ -58,12 +48,7 @@ void setup()
 	byte digitPins[] = {9, 10, 11, 12};
 	byte segmentPins[] = {2, 3, 4, 5, 6, 7, 8, 13};
 	bool resistorsOnSegments = true; // 8 resistors, 330 Ohms each
-	/* updateWithDelays defaults to false and it is recommended value,
-	 * but i was unable to make my display to change brightness notably with
-	 * recommended value, so i have to use updateWithDelays=true,
-	 * in this case brightness gets changed.
-	 */
-	bool updateWithDelays = true;
+	bool updateWithDelays = false;   // Default. Recommended
 
 	/* without it there is visual bug at 0 o'clock, and in current version
 	 * of SevSeg' setChars() does not dots at all */
@@ -105,18 +90,6 @@ void setup()
 	TCCR1B |= (1 << CS12);    // 256 prescaler 
 	TIMSK1 |= (1 << TOIE1);   // enable timer overflow interrupt
 	interrupts();             // enable all interrupts
-
-/* increase sampling rate of analogRead()
- * by setting an ADC prescale from 128 to 16, so it takes less time to read
- * sensor
- */
-	sbi(ADCSRA, ADPS2);
-	cbi(ADCSRA, ADPS1);
-	cbi(ADCSRA, ADPS0);
-
-	// setup ambient brigtness sensor
-	pinMode(photoPin, INPUT);
-	ambLight = analogRead(photoPin);
 }
 
 ISR(TIMER1_OVF_vect)
@@ -213,53 +186,6 @@ void loop()
 		updateTimeStr(myhour, myminute);
 	}
 
-	if ((currentMillis - previousLightTimer >= refresh_interval) or
-	    (previousLightTimer > currentMillis)) { // millis() reset every ~49 days
-		previousLightTimer = currentMillis;
-		ambLight = analogRead(photoPin);
-
-/* Ambient light compensation
- * ambLight can be in range of 0..1023, if it 910+, it has point to use
- * fullbright.
- * Use table comparsion (not function of ambLight) because of non-linear
- * charachteristics of led indicator, that cannot be described via simple
- * formula.
- */
-		if (ambLight >= 910) {
-			Display.setBrightness(100);
-		} else if ((ambLight < 900) and (ambLight >= 860)) {
-			Display.setBrightness(75);
-		} else if ((ambLight < 850) and (ambLight >= 810)) { 
-			Display.setBrightness(45);
-		} else if ((ambLight < 800) and (ambLight >= 760)) {
-			Display.setBrightness(25);
-		} else if ((ambLight < 750) and (ambLight >= 710)) {
-			Display.setBrightness(18);
-		} else if ((ambLight < 700) and (ambLight >= 660)) {
-			Display.setBrightness(12);
-		} else if ((ambLight < 650) and (ambLight >= 610)) {
-			Display.setBrightness(10);
-		} else if ((ambLight < 600) and (ambLight >= 560)) {
-			Display.setBrightness(7);
-		} else if ((ambLight < 550) and (ambLight >= 410)) {
-			Display.setBrightness(4);
-		} else if ((ambLight < 400) and (ambLight >= 360)) {
-			Display.setBrightness(0);
-		} else if ((ambLight < 350) and (ambLight >= 310)) {
-			Display.setBrightness(-3);
-		} else if ((ambLight < 300) and (ambLight >= 260)) {
-			Display.setBrightness(-6);
-		} else if ((ambLight < 250) and (ambLight >= 210)) {
-			Display.setBrightness(-10);
-		} else if ((ambLight < 200) and (ambLight >= 160)) {
-			Display.setBrightness(-14);
-		} else if ((ambLight < 150) and (ambLight >= 110)) {
-			Display.setBrightness(-18);
-		} else if (ambLight < 100) {
-			Display.setBrightness(-22);
-		}
-	}
-
 	Display.refreshDisplay();
 }
 
@@ -275,4 +201,5 @@ void updateTimeStr(uint8_t h, uint8_t m)
 		Display.setChars(str);
 	}
 }
+
 /* vim: set filetype=cpp: */