Update display text only by interrupt or on button press

* Re-calculate displayed time only ater rtcsync or when time adjusted by
  buttons

.gitignore

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

.hgtags

@@ -1 +0,0 @@
-ee4999ebdd2d1b54512facafdd03c8a530ea4bfa v1.0

README.md

@@ -4,13 +4,25 @@
 
 ### Component base is very simple:
 
-* Arduino NANO v3 chinese replica
+* Arduino NANO v3 chinese replica (on Atmega-168 chip)
-* 7 segment 4 digit LED indicator with common anode, FYQ-5641BG-21
+* 7 segment 4 digit LED indicator with common anode, FYQ-5641BD-21 (red LEDs)
 * 8 resistors that limiting current on LED segments, 330 Ohms, 0.25 watts
-* RTC Module GEEGROW with DS1307 chip
+* RTC Module GEEGROW with DS1307 chip (very basic, only RTC chip, quartz resonator, button battery, no additional memory chip)
 * 5x7 cm single side prototyping board
 * 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
+
+### Optionally you may need:
+
+* Capasitor with well capacity if your charger has small capasitor on output
+* Fuse, to protect your device
+* DC/DC transformer if you have power supply that gives more than 5 volts or less than 4.5 volts (this will give additional surge protection if your power supply dies, this can happen after 3-5 years of uninterrupted work)
+
+### 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).

simpleclock.ino

@@ -1,53 +1,54 @@
 /*
- *           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
+ * It uses display module with common anode and DS1307 RTC module to enhance
- *           RTC module to enhance time keeping ability of
+ * time keeping ability of Atmega 328p based Arduino Nano microcontroller and
- *           Atmega 328p based Arduino nano microcontroller and
+ * 2 buttons for adjusting time.
- *           2 buttons for adjusting time.
  */
 
-/* This software distributed under BSD 2 Clause License
+/* DS1307 lib by FrankieChu for Seeed RTC module, in my case
-
+ * Grove___RTC_DS1307-1.0.0.zip */
-Copyright (c) Sergei Fedosoff, All rights reserved.
-
-Redistribution and use in source and binary forms, with or without modification,
-are permitted provided that the following conditions are met:
-
-Redistributions of source code must retain the above copyright notice, this list
-of conditions and the following disclaimer. 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. THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS 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 COPYRIGHT HOLDER 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.
-*/
-
-#include <SevSeg.h>
-#include <Wire.h>
-#include <TimeLib.h>
-// DS1307 lib by FrankieChu for Seeed RTC module
 #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;
 
-unsigned long currentMillis;
+/* push button stuff */
-unsigned long previousMillis = 0;
+const long initial_delay = 600;   // wait a bit before spin numbers
-const long interval = 500;
+const long adjust_interval = 200; // delay between consecutive number increments
-const int hrs_btn = A0;
+const long bounce_delay = 20;     // contact bounce compensation
-const int min_btn = A1;
+const int hrs_btn = A0;           // put hour adjusting button on A0 lane
-bool dot = true;
+const int min_btn = A1;           // put minute adjusting button on A1 lane
-uint8_t minutes;
+volatile bool btn_pushed = false; // is button pushed?
-uint8_t hours;
+unsigned long previousPushTimer = 0;
+
+/* dot blinking stuff */
+volatile bool dot = true;
+
+/* time inaccuracy compensation flag */
+volatile bool compflag1 = true;
+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;
+volatile uint8_t myhour;
+
+/* rtc sync flag */
+volatile bool rtcsync = true;
 
 void setup()
 {
@@ -56,15 +57,21 @@ void setup()
 	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 resistorsOnSegments = true; // 8 resistors, 330 Ohms each
-	bool updateWithDelays = false;     // Default. Recommended
+	/* updateWithDelays defaults to false and it is recommended value,
-	/* without it there is visual bug at 0 o'clock, and in current version of
+	 * but i was unable to make my display to change brightness notably with
-	 * SevSeg' setChars() does not dots at all */
+	 * 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 */
 	bool leadingZeros = false;
 
 	Display.begin(hardwareConfig, numDigits, digitPins, segmentPins,
-                      resistorsOnSegments, updateWithDelays, leadingZeros);
+	              resistorsOnSegments, updateWithDelays, leadingZeros);
-	Display.setBrightness(90);
+	Display.setBrightness(100);
 
 	// setup clock
 	clock.begin();
@@ -72,89 +79,213 @@ void setup()
 	// if rtc returns incorrect time, reset it to some default value
 	clock.getTime();
 
-	if (( clock.hour > 23 ) || (clock.minute > 59))
+	if ((clock.hour > 23) || (clock.minute > 59)) {
-	{
+		clock.fillByYMD(2019, 2, 23); // 23 Feb 2019
-		clock.fillByYMD(2019,2,23);  // 23 Feb 2013
+		clock.fillByHMS(15, 52, 30);  // 15:52:30"
-		clock.fillByHMS(15,52,30);   // 15:52 30"
+		clock.fillDayOfWeek(SAT);     // Saturday
-		clock.fillDayOfWeek(SAT);    // Saturday
+		clock.setTime();              // put date to rtc
-		clock.setTime();             // put date to rtc
 	}
 
 	// 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;
+
+/* time compensation magic */
+	if ((myhour == 21) and (myminute == 21) and (mysecond == 21)
+	    and (compflag2)) {
+		compflag1 = true;
+		(timeSkewEven) ? timeSkewEven = false : timeSkewEven;
+	}
+
+	if ((myhour == 21) and (myminute == 21) and (mysecond == 23)) {
+		compflag1 = false;
+		compflag2 = true;
+	}
+}
 
 void loop()
 {
 	unsigned long currentMillis = millis();
-	char str[4];
-	float d;
 
-	if (currentMillis - previousMillis >= interval)
+/*
-	{
+ * Let's implement time compenstion for individual rtc module time
-		previousMillis = currentMillis;
+ * charachteristics. In in my case quartz resonator as inaccurate as
-
+ * about +8.5 seconds per 24 hours
-		if (dot == false)
+ */
-		{
+	if (compflag1 && compflag2) {
-			dot = true;
+		if (timeSkewEven) {
-
+			clock.fillByHMS(myhour, myminute, (mysecond - timeSkew - 1));
-			if (digitalRead(hrs_btn) == LOW)
+		} else {
-			{
+			clock.fillByHMS(myhour, myminute, (mysecond - timeSkew));
-				clock.getTime();
-				hours = clock.hour + 1;
-				(hours > 23)? hours = 0: hours;
-				clock.fillByHMS(hours, clock.minute, 0);
-				clock.setTime();
-			}
-
-			if (digitalRead(min_btn) == LOW)
-			{
-				clock.getTime();
-				minutes = clock.minute + 1;
-				(minutes > 59)? minutes = 0: minutes;
-				clock.fillByHMS(clock.hour, minutes, 0);
-				clock.setTime();
-			}
 		}
-		else
+
-		{
+		clock.setTime();
-			dot = false;
+		compflag2 = false;
+	}
+
+	if (rtcsync) {
+		clock.getTime();
+		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 (currentMillis - previousPushTimer >= initial_delay) {
+			previousPushTimer = currentMillis;
+			btn_pushed = true;
 		}
 	}
 
-	clock.getTime();
+	if (btn_pushed and
-
+	    (digitalRead(hrs_btn) != LOW) and (digitalRead(min_btn) != LOW)) {
-	// make blinking dot
+		// compensate possible contact bounce with delay
-	if (clock.hour > 0)
+		if (currentMillis - previousPushTimer >= bounce_delay) {
-	{
+			btn_pushed = false;
-		if (dot == true) 
-		{
-			Display.setNumber((clock.hour * 100 + clock.minute), 2);
-		}
-		else
-		{
-			Display.setNumber((clock.hour * 100 + clock.minute));
 		}
 	}
-	else
+
-	{
+	if (btn_pushed) {
-		/* 0 o'clock is an exception, we dont want to see "00.00", we want see
+		if (currentMillis - previousPushTimer >= adjust_interval) {
-		 * "0.00" or "0 00", so we have to use this "hack" */
+			previousPushTimer = currentMillis;
-		if (dot == true)
+
-		{
+			if (digitalRead(hrs_btn) == LOW) {
-			d = float(clock.minute) / 100;
+				myhour++;
-			Display.setNumber(d, 2);
+				(myhour > 23) ? myhour = 0 : myhour;
+				clock.fillByHMS(myhour, myminute, 0);
+				clock.setTime();
+			}
+
+			if (digitalRead(min_btn) == LOW) {
+				myminute++;
+				(myminute > 59) ? myminute = 0 : myminute;
+				clock.fillByHMS(myhour, myminute, 0);
+				clock.setTime();
+			}
 		}
-		else
+
-		{
+		updateTimeStr(myhour, myminute);
-			sprintf(str, "%2d%02d", clock.hour, clock.minute);
+	}
-			Display.setChars(str);
+
+	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(-5);
+		} else if ((ambLight < 250) and (ambLight >= 210)) {
+			Display.setBrightness(-7);
+		} else if ((ambLight < 200) and (ambLight >= 160)) {
+			Display.setBrightness(-9);
+		} else if ((ambLight < 150) and (ambLight >= 110)) {
+			Display.setBrightness(-12);
+		} else if (ambLight < 100) {
+			Display.setBrightness(-15);
 		}
 	}
 
 	Display.refreshDisplay();
 }
 
+void updateTimeStr(uint8_t h, uint8_t m)
+{
+	char str[4];
+	float d;
+
+	// make blinking dot
+	if (h > 0) {
+		if (dot) {
+			Display.setNumber((h * 100 + m), 2);
+		} else {
+			Display.setNumber((h * 100 + m));
+		}
+	} 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(m) / 100;
+			Display.setNumber(d, 2);
+		} else {
+			sprintf(str, "%2d%02d", h, m);
+			Display.setChars(str);
+		}
+	}
+	
+}
 /* vim: set filetype=cpp: */