Init battery for ds3231 explicitly, code style fixes

* move Time Compensation feature under define
* translte last few eol to unix style
* make correction: in my case with bad chrystal rtc runs faster about
  9.5 seconds per day

.gitignore

@@ -1,6 +0,0 @@
-.vscode/*
-*.swp
-*.bak
-*.old
-*.orig
-*.clang-format

README.md

@@ -12,6 +12,8 @@
 * 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
 
@@ -24,12 +26,3 @@
 ### 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

@@ -1,20 +1,35 @@
-/*
+/* 7 Segment 4 Digits clock with digit point separator.
- * 7 Segment 4 Digits clock with digit point separator
  *
- * It uses display module with common anode and DS1307 RTC module to enhance
+ * It uses display module with common anode and DS1307/DS3231 RTC module to
- * time keeping ability of Atmega 328p based Arduino Nano microcontroller and
+ * enhance time keeping ability of Atmega 328p based Arduino Nano 
- * 2 buttons for adjusting time.
+ * microcontroller and 2 buttons for adjusting time. */
- */
 
-/* DS1307 lib by FrankieChu for Seeed RTC module, in my case
+/* uRTCLib
- * Grove___RTC_DS1307-1.0.0.zip */
+ * https://github.com/Naguissa/uRTCLib
-#include <DS1307.h>
+ * it has support for both DS1307 and DS3231, that I have.
+ * It is more fat than ds1307-dedicated or ds3231-dedicated lib, but I do not
+ * want to re-invent wheel if I have one. */
+#include <uRTCLib.h>
+
+/* SevSeg
+ * https://github.com/DeanIsMe/SevSeg
+ * it has simple api and ideally works in my case.  */
 #include <SevSeg.h>
 
-DS1307 clock;
+/* Disable time compensation.
+ * At last we borrow more accurate chrystal and solder it to rtc breakboard.
+ */
+//#define TIMECOMP
+// 0.5 second/day compensation flag.
+//#define OFIVECOMP
+
+#define cbi(sfr, bit) (_SFR_BYTE(sfr) &= ~_BV(bit))
+#define sbi(sfr, bit) (_SFR_BYTE(sfr) |= _BV(bit))
+
+uRTCLib clock;
 SevSeg Display;
 
-/* push button stuff */
+// Push button stuff.
 const long initial_delay = 600;   // wait a bit before spin numbers
 const long adjust_interval = 200; // delay between consecutive number increments
 const long bounce_delay = 20;     // contact bounce compensation
@@ -23,131 +38,187 @@ const int min_btn = A1;           // put minute adjusting button on A1 lane
 volatile bool btn_pushed = false; // is button pushed?
 unsigned long previousPushTimer = 0;
 
-/* dot blinking stuff */
+// Dot blinking stuff.
 volatile bool dot = true;
 
-/* time inaccuracy compensation flag */
+#ifdef TIMECOMP
+// Time inaccuracy compensation flag.
 volatile bool compflag1 = true;
 volatile bool compflag2 = false;
-const uint8_t timeSkew = 8;          // assume that clock runs faster than should
+const uint8_t timeSkew = 9;          // Assume that clock runs faster than should.
-volatile bool timeSkewEven = false;  // comp. 1 additional second per 2 days
+#ifdef OFIVECOMP
+volatile bool timeSkewEven = false;  // Comp. 1 additional second per 2 days.
+#endif
+#endif
 
-/* time vars */
+// Ambient light compensation aka night mode.
+const int photoPin = A2;
+volatile bool measureAmbLight = true;
+unsigned int ambLight = 0;           // Actual value.
+unsigned long previousLightTimer = 0;
+const long refresh_interval = 40;    // Refresh rate 25Hz.
+
+// Time vars.
 volatile uint8_t mysecond;
 volatile uint8_t myminute;
 volatile uint8_t myhour;
 
-/* rtc sync flag */
+// RTC sync flag.
 volatile bool rtcsync = true;
 
 void setup()
 {
-	// setup display
+	// Setup display.
 	byte hardwareConfig = COMMON_ANODE;
 	byte numDigits = 4;
 	byte digitPins[] = {9, 10, 11, 12};
 	byte segmentPins[] = {2, 3, 4, 5, 6, 7, 8, 13};
 	bool resistorsOnSegments = true; // 8 resistors, 330 Ohms each
-	bool updateWithDelays = false;   // Default. Recommended
+	/* 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;
 
-	/* without it there is visual bug at 0 o'clock, and in current version
+	/* Without it there is visual bug at 0 o'clock, and in current version
-	 * of SevSeg' setChars() does not dots at all */
+	 * of SevSeg' setChars() does not dots at all. */
 	bool leadingZeros = false;
 
 	Display.begin(hardwareConfig, numDigits, digitPins, segmentPins,
 	              resistorsOnSegments, updateWithDelays, leadingZeros);
 	Display.setBrightness(100);
 
-	// setup clock
+	// Init i2c bus and setup clock address.
-	clock.begin();
+	Wire.begin();
+	clock.set_rtc_address(0x68);
 
-	// if rtc returns incorrect time, reset it to some default value
+	// If rtc returns incorrect time, reset it to some default values.
-	clock.getTime();
+	clock.refresh();
 
-	if ((clock.hour > 23) || (clock.minute > 59)) {
+	if (clock.lostPower()) {
-		clock.fillByYMD(2019, 2, 23); // 23 Feb 2019
+		clock.set(30, 52, 15, 6, 23, 2, 19); // Saturday, 23 Feb 2019 15:52:30
-		clock.fillByHMS(15, 52, 30);  // 15:52:30"
+		clock.lostPowerClear();
-		clock.fillDayOfWeek(SAT);     // Saturday
-		clock.setTime();              // put date to rtc
 	}
 
-	// setup control buttons
+	if ((clock.hour() > 23) || (clock.minute() > 59)) {
+		clock.set(30, 52, 15, 6, 23, 2, 19); // Saturday, 23 Feb 2019 15:52:30
+	}
+
+	/* In case of ds1307 this will be noop, but ds3231/ds3232 sometimes does
+	 * not enable battery by default. */
+	clock.enableBattery();
+
+	// Setup control buttons.
 	pinMode(hrs_btn, INPUT_PULLUP);
 	pinMode(min_btn, INPUT_PULLUP);
 
-/* Timer stuff
+	/* Timer stuff.
- * timer0 being used in millis() micros() delay() etc, it has 8 bit resolution
+	 * timer0 being used in millis() micros() delay() etc, it has 8 bit resolution.
- * timer2 being used in analogWrite() tone() notone(), it has 8 bit resolution
+	 * timer2 being used in analogWrite() tone() notone(), it has 8 bit resolution.
- * timer1 being used in servo lib has 16 bit resolution
+	 * timer1 being used in servo lib has 16 bit resolution.
- * We'll use timer1, since we have no mechanical parts and don't need servo lib
+	 * We'll use timer1, since we have no mechanical parts and don't need servo lib */
- */
+
-	// initialize timer1
+	// Initialize timer1.
-	noInterrupts();           // disable all interrupts
+	noInterrupts();           // Disable all interrupts.
 	TCCR1A = 0;
 	TCCR1B = 0;
 
-	TCNT1 = 34286;            // preload timer 65536-16MHz/256/2Hz
+	TCNT1 = 34286;            // Preload timer 65536-16MHz/256/2Hz
 	TCCR1B |= (1 << CS12);    // 256 prescaler 
-	TIMSK1 |= (1 << TOIE1);   // enable timer overflow interrupt
+	TIMSK1 |= (1 << TOIE1);   // Enable timer overflow interrupt.
-	interrupts();             // enable all interrupts
+	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)
 {
-/* Feed clock twice per second */
+	// Feed clock twice per second.
-	TCNT1 = 34286;            // preload timer
+	TCNT1 = 34286;            // Preload timer.
-	// do not read rtc if time beng adjusted by buttons
+	// Do not read rtc if time beng adjusted by buttons.
 	(btn_pushed) ? rtcsync : rtcsync = true;
 
-/* Also switch dot */
+	// Also switch dot.
 	if (dot)
 		dot = false;
 	else
 		dot = true;
 
-/* time compensation magic */
+#ifdef TIMECOMP
+	// Time compensation magic.
 	if ((myhour == 21) and (myminute == 21) and (mysecond == 21)
 	    and (compflag2)) {
 		compflag1 = true;
+#ifdef OFIVECOMP
 		(timeSkewEven) ? timeSkewEven = false : timeSkewEven;
+#endif
 	}
 
 	if ((myhour == 21) and (myminute == 21) and (mysecond == 23)) {
 		compflag1 = false;
 		compflag2 = true;
 	}
+#endif
 }
 
 void loop()
 {
 	unsigned long currentMillis = millis();
 
-/*
+#ifdef TIMECOMP
- * Let's implement time compenstion for individual rtc module time
+	/* Let's implement time compensation for individual rtc module time
- * charachteristics. In in my case quartz resonator as inaccurate as
+	 * characteristics. In in my case quartz resonator as inaccurate as
- * about +8.5 seconds per 24 hours
+	 * about +9.5 seconds per 24 hours. */
- */
 	if (compflag1 && compflag2) {
+#ifdef OFIVECOMP
 		if (timeSkewEven) {
-			clock.fillByHMS(myhour, myminute, (mysecond - timeSkew - 1));
+			clock.set(
+				(mysecond - timeSkew - 1),
+				clock.minute(),
+				clock.hour(),
+				clock.dayOfWeek(),
+				clock.day(),
+				clock.month(),
+				clock.year()
+			);
 		} else {
-			clock.fillByHMS(myhour, myminute, (mysecond - timeSkew));
+#endif
+			clock.set(
+				(mysecond - timeSkew),
+				clock.minute(),
+				clock.hour(),
+				clock.dayOfWeek(),
+				clock.day(),
+				clock.month(),
+				clock.year()
+			);
+#ifdef OFIVECOMP
 		}
+#endif
 
-		clock.setTime();
 		compflag2 = false;
 	}
+#endif
 
 	if (rtcsync) {
-		clock.getTime();
+		clock.refresh();
-		mysecond = clock.second;
+		mysecond = clock.second();
-		myminute = clock.minute;
+		myminute = clock.minute();
-		myhour = clock.hour;
+		myhour = clock.hour();
 		updateTimeStr(myhour, myminute);
 		rtcsync = false;
 	}
 
-	// push button magic
+	// Push button magic.
 	if ((!btn_pushed) and
 	    ((digitalRead(hrs_btn) == LOW) or (digitalRead(min_btn) == LOW))) {
 		if (currentMillis - previousPushTimer >= initial_delay) {
@@ -171,21 +242,81 @@ void loop()
 			if (digitalRead(hrs_btn) == LOW) {
 				myhour++;
 				(myhour > 23) ? myhour = 0 : myhour;
-				clock.fillByHMS(myhour, myminute, 0);
+				clock.set(
-				clock.setTime();
+					0,
+					myminute,
+					myhour,
+					clock.dayOfWeek(),
+					clock.day(),
+					clock.month(),
+					clock.year()
+				);
 			}
 
 			if (digitalRead(min_btn) == LOW) {
 				myminute++;
 				(myminute > 59) ? myminute = 0 : myminute;
-				clock.fillByHMS(myhour, myminute, 0);
+				clock.set(
-				clock.setTime();
+					0,
+					myminute,
+					myhour,
+					clock.dayOfWeek(),
+					clock.day(),
+					clock.month(),
+					clock.year()
+				);
 			}
 		}
 
 		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
+		 * characteristics 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();
 }
 
@@ -202,4 +333,5 @@ void updateTimeStr(uint8_t h, uint8_t m)
 	}
 }
 
+
 /* vim: set filetype=cpp: */