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

.hgignore

@@ -1,6 +0,0 @@
-^\.vscode
-\.swp$
-\.bak$
-\.old$
-\.orig$
-\.clang-format

.hgtags

@@ -1,3 +0,0 @@
-ee4999ebdd2d1b54512facafdd03c8a530ea4bfa v1.0
-1167bd4b622768ed17e116a4cbac3db90031e6f8 v1.1
-109112211e454e608911949914eaa2722fbfed7d v1.2

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:
-v1.5 - default
-v1.4 - photoresistor

simpleclock.ino

@@ -1,90 +1,228 @@
-/*
- * 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
- * time keeping ability of Atmega 328p based Arduino Nano microcontroller and
- * 2 buttons for adjusting time.
- */
+ * It uses display module with common anode and DS1307/DS3231 RTC module to
+ * enhance time keeping ability of Atmega 328p based Arduino Nano 
+ * microcontroller and 2 buttons for adjusting time. */
 
-/* DS1307 lib by FrankieChu for Seeed RTC module, in my case
- * Grove___RTC_DS1307-1.0.0.zip */
-#include <DS1307.h>
+/* uRTCLib
+ * https://github.com/Naguissa/uRTCLib
+ * 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
 const int hrs_btn = A0;           // put hour adjusting button on A0 lane
 const int min_btn = A1;           // put minute adjusting button on A1 lane
-bool btn_pushed = false;          // is button pushed?
-unsigned long currentPushTimer;
+volatile bool btn_pushed = false; // is button pushed?
 unsigned long previousPushTimer = 0;
-uint8_t minutes;
-uint8_t hours;
 
-/* dot blinking stuff */
-unsigned long currentMillis;
-unsigned long previousMillis = 0;
-const long interval = 500;
-bool dot = true;
+// Dot blinking stuff.
+volatile bool dot = true;
 
-/* time inaccuracy compensation flag */
-bool compflag = true;
+#ifdef TIMECOMP
+// Time inaccuracy compensation flag.
+volatile bool compflag1 = true;
+volatile bool compflag2 = false;
+const uint8_t timeSkew = 9;          // Assume that clock runs faster than should.
+#ifdef OFIVECOMP
+volatile bool timeSkewEven = false;  // Comp. 1 additional second per 2 days.
+#endif
+#endif
+
+// 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.
+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
-	 * of SevSeg' setChars() does not dots at all */
+	/* Without it there is visual bug at 0 o'clock, and in current version
+	 * 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
-	clock.begin();
+	// Init i2c bus and setup clock address.
+	Wire.begin();
+	clock.set_rtc_address(0x68);
 
-	// if rtc returns incorrect time, reset it to some default value
-	clock.getTime();
+	// If rtc returns incorrect time, reset it to some default values.
+	clock.refresh();
 
-	if ((clock.hour > 23) || (clock.minute > 59)) {
-		clock.fillByYMD(2019, 2, 23); // 23 Feb 2019
-		clock.fillByHMS(15, 52, 30);  // 15:52:30"
-		clock.fillDayOfWeek(SAT);     // Saturday
-		clock.setTime();              // put date to rtc
+	if (clock.lostPower()) {
+		clock.set(30, 52, 15, 6, 23, 2, 19); // Saturday, 23 Feb 2019 15:52:30
+		clock.lostPowerClear();
 	}
 
-	// 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.
+	 * 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.
+	 * 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 */
+
+	// Initialize timer1.
+	noInterrupts();           // Disable all interrupts.
+	TCCR1A = 0;
+	TCCR1B = 0;
+
+	TCNT1 = 34286;            // Preload timer 65536-16MHz/256/2Hz
+	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)
+{
+	// Feed clock twice per second.
+	TCNT1 = 34286;            // Preload timer.
+	// Do not read rtc if time beng adjusted by buttons.
+	(btn_pushed) ? rtcsync : rtcsync = true;
+
+	// Also switch dot.
+	if (dot)
+		dot = false;
+	else
+		dot = true;
+
+#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()
 {
-	currentMillis = millis();
-	currentPushTimer = currentMillis;
-	char str[4];
-	float d;
+	unsigned long currentMillis = millis();
 
-	clock.getTime();
+#ifdef TIMECOMP
+	/* Let's implement time compensation for individual rtc module time
+	 * characteristics. In in my case quartz resonator as inaccurate as
+	 * about +9.5 seconds per 24 hours. */
+	if (compflag1 && compflag2) {
+#ifdef OFIVECOMP
+		if (timeSkewEven) {
+			clock.set(
+				(mysecond - timeSkew - 1),
+				clock.minute(),
+				clock.hour(),
+				clock.dayOfWeek(),
+				clock.day(),
+				clock.month(),
+				clock.year()
+			);
+		} else {
+#endif
+			clock.set(
+				(mysecond - timeSkew),
+				clock.minute(),
+				clock.hour(),
+				clock.dayOfWeek(),
+				clock.day(),
+				clock.month(),
+				clock.year()
+			);
+#ifdef OFIVECOMP
+		}
+#endif
 
-	// push button magic
+		compflag2 = false;
+	}
+#endif
+
+	if (rtcsync) {
+		clock.refresh();
+		mysecond = clock.second();
+		myminute = clock.minute();
+		myhour = clock.hour();
+		updateTimeStr(myhour, myminute);
+		rtcsync = false;
+	}
+
+	// Push button magic.
 	if ((!btn_pushed) and
 	    ((digitalRead(hrs_btn) == LOW) or (digitalRead(min_btn) == LOW))) {
-		if (currentPushTimer - previousPushTimer >= initial_delay) {
-			previousPushTimer = currentPushTimer;
+		if (currentMillis - previousPushTimer >= initial_delay) {
+			previousPushTimer = currentMillis;
 			btn_pushed = true;
 		}
 	}
@@ -92,79 +230,108 @@ void loop()
 	if (btn_pushed and
 	    (digitalRead(hrs_btn) != LOW) and (digitalRead(min_btn) != LOW)) {
 		// compensate possible contact bounce with delay
-		if (currentPushTimer - previousPushTimer >= bounce_delay) {
+		if (currentMillis - previousPushTimer >= bounce_delay) {
 			btn_pushed = false;
 		}
 	}
 
 	if (btn_pushed) {
-		if (currentPushTimer - previousPushTimer >= adjust_interval) {
-			previousPushTimer = currentPushTimer;
+		if (currentMillis - previousPushTimer >= adjust_interval) {
+			previousPushTimer = currentMillis;
 
 			if (digitalRead(hrs_btn) == LOW) {
-				hours = clock.hour + 1;
-				(hours > 23) ? hours = 0 : hours;
-				clock.fillByHMS(hours, clock.minute, 0);
-				clock.setTime();
+				myhour++;
+				(myhour > 23) ? myhour = 0 : myhour;
+				clock.set(
+					0,
+					myminute,
+					myhour,
+					clock.dayOfWeek(),
+					clock.day(),
+					clock.month(),
+					clock.year()
+				);
 			}
 
 			if (digitalRead(min_btn) == LOW) {
-				minutes = clock.minute + 1;
-				(minutes > 59) ? minutes = 0 : minutes;
-				clock.fillByHMS(clock.hour, minutes, 0);
-				clock.setTime();
+				myminute++;
+				(myminute > 59) ? myminute = 0 : myminute;
+				clock.set(
+					0,
+					myminute,
+					myhour,
+					clock.dayOfWeek(),
+					clock.day(),
+					clock.month(),
+					clock.year()
+				);
 			}
 		}
+
+		updateTimeStr(myhour, myminute);
 	}
 
-	if (currentMillis - previousMillis >= interval) {
-		previousMillis = currentMillis;
+	if ((currentMillis - previousLightTimer >= refresh_interval) or
+	    (previousLightTimer > currentMillis)) { // millis() reset every ~49 days
+		previousLightTimer = currentMillis;
+		ambLight = analogRead(photoPin);
 
-		if (dot)
-			dot = false;
-		else
-			dot = true;
-	}
-
-	/*
-	 * Let's implement time compenstion for individual rtc module time
-	 * charachteristics. In in my case quartz resonator as inaccurate as
-	 * +/- about 5-8 seconds per 24 hours, maybe its require more EMI
-	 * shielding?
-	 */
-
-	if ((clock.hour == 21) and (clock.minute == 21) and
-	    (clock.second == 21) and (compflag)) {
-		clock.fillByHMS(clock.hour, clock.minute, 14);
-		clock.setTime();
-		compflag = false;
-	}
-
-	if ((clock.hour == 21) and (clock.minute == 21) and
-	    (clock.second == 23) and (!compflag)) {
-		compflag = true;
-	}
-
-	// make blinking dot
-	if (clock.hour > 0) {
-		if (dot) {
-			Display.setNumber((clock.hour * 100 + clock.minute), 2);
-		} else {
-			Display.setNumber((clock.hour * 100 + clock.minute));
-		}
-	} else {
-		/* 0 o'clock is an exception, we don't want to see "00.00", we
-		   want see "0.00" or "0 00", so we have to use this "hack" */
-		if (dot) {
-			d = float(clock.minute) / 100;
-			Display.setNumber(d, 2);
-		} else {
-			sprintf(str, "%2d%02d", clock.hour, clock.minute);
-			Display.setChars(str);
+		/* 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();
 }
 
+void updateTimeStr(uint8_t h, uint8_t m)
+{
+	if (dot) {
+		char str[5];
+		sprintf(str, "%2d.%02d", h, m);
+		Display.setChars(str);
+	} else {
+		char str[4];
+		sprintf(str, "%2d%02d", h, m);
+		Display.setChars(str);
+	}
+}
+
+
 /* vim: set filetype=cpp: */