From 825c3096f2ebf839593877529e6d48247d350e6d Mon Sep 17 00:00:00 2001
From: eleksir <eleksir@exs-elm.ru>
Date: Sat, 20 Apr 2019 12:04:05 +0300
Subject: [PATCH] Implement software time inaccuracy compensation hack

32768 Hz quartz chrystal resonator tends to be a bit inaccurate giving
about 5-10 seconds per day time skew
---
 simpleclock.ino | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/simpleclock.ino b/simpleclock.ino
index 49a12f8..f3ee3c9 100644
--- a/simpleclock.ino
+++ b/simpleclock.ino
@@ -48,6 +48,8 @@ const int min_btn = A1;
 bool dot = true;
 uint8_t minutes;
 uint8_t hours;
+/* time inaccuracy compensation flag */
+uint8_t compflag = 0;
 
 void setup()
 {
@@ -125,6 +127,23 @@ void loop()
 	}
 
 	clock.getTime();
+  /*
+   * 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
+   * sheilding?
+   */
+
+	if ((clock.hour == 21) and (clock.minute == 21) and (clock.second == 21) and (compflag == 0)) {
+		clock.second = 14;
+		clock.fillByHMS(clock.hour,clock.minute,clock.second);
+		clock.setTime();
+		compflag = 1;
+	}
+
+	if ((clock.hour == 21) and (clock.minute == 21) and (clock.second == 23) and (compflag == 1)) {
+		compflag = 0;
+	}
 
 	// make blinking dot
 	if (clock.hour > 0)