Добавлен переход на летнее/зимнее время; Добавлен эффект Белый огонь; Исправлены ошибки

2025-08-11 10:40:41 +03:00 · 2019-11-02 19:30:10 +02:00
parent 08d5d6022a
commit 0413e435db
24 changed files with 1917 additions and 67 deletions
--- a/libraries/Timezone/examples/Change_TZ_1/Change_TZ_1.ino
+++ b/libraries/Timezone/examples/Change_TZ_1/Change_TZ_1.ino
@@ -0,0 +1,119 @@
+// Arduino Timezone Library Copyright (C) 2018 by Jack Christensen and
+// licensed under GNU GPL v3.0, https://www.gnu.org/licenses/gpl.html
+//
+// Arduino Timezone Library example sketch.
+// Demonstrates changing timezone "on the fly".
+// Uses a pushbutton switch to change between the four continental US time zones.
+// The current timezone setting is saved in EEPROM so it is remembered if
+// the power is cycled.
+// Tested with Arduino 1.8.5 and an Arduino Uno.
+//
+// Jack Christensen 02Jan2018
+
+#include <avr/eeprom.h>
+#include <JC_Button.h>          // http://github.com/JChristensen/JC_Button
+#include <Streaming.h>          // http://arduiniana.org/libraries/streaming/
+#include <Timezone.h>           // http://github.com/JChristensen/Timezone
+
+const uint8_t BUTTON_PIN(8);    // connect a button from this pin to ground
+Button btn(BUTTON_PIN);
+
+uint8_t tzIndex;            //index to the arrays below
+EEMEM uint8_t ee_tzIndex;   //copy of tzIndex persisted in EEPROM
+const char* dstNames[] = {"EDT", "CDT", "MDT", "PDT"};
+const char* stdNames[] = {"EST", "CST", "MST", "PST"};
+const int dstOffsets[] = {-240, -300, -360, -420};
+const int stdOffsets[] = {-300, -360, -420, -480};
+
+TimeChangeRule dstRule = {"EDT", Second, Sun, Mar, 2, -240};
+TimeChangeRule stdRule = {"EST", First, Sun, Nov, 2, -300};
+Timezone tz(dstRule, stdRule);
+
+void setup()
+{
+    // set the system time to UTC
+    // warning: assumes that compileTime() returns US EST
+    // adjust the following line accordingly if you're in another time zone
+    setTime(compileTime() + 300 * 60);
+
+    // get tzIndex from eeprom and ensure that it's valid
+    tzIndex = eeprom_read_byte( &ee_tzIndex );
+    if ( tzIndex >= sizeof(stdOffsets) / sizeof(stdOffsets[0]) )
+    {
+        tzIndex = 0;
+        eeprom_write_byte( &ee_tzIndex, tzIndex);
+    }
+
+    btn.begin();
+    Serial.begin(115200);
+    changeTZ();
+}
+
+void loop()
+{
+    // print the time if it's changed
+    static time_t tLast;
+    time_t t = now();
+    if (t != tLast)
+    {
+        tLast = t;
+        printDateTime(t);
+        Serial << " UTC  ";
+        TimeChangeRule* tcr;    //pointer to current time change rule, used to get TZ abbrev
+        printDateTime(tz.toLocal(t, &tcr));
+        Serial << " " << tcr -> abbrev;
+        Serial << endl;
+    }
+
+    // change the time zone if button pressed
+    btn.read();
+    if (btn.wasPressed())
+    {
+        if ( ++tzIndex >= sizeof(stdOffsets) / sizeof(stdOffsets[0]) ) tzIndex = 0;
+        changeTZ();
+    }
+}
+
+void changeTZ()
+{
+    Serial << "tzIndex " << tzIndex << endl;
+    eeprom_update_byte( &ee_tzIndex, tzIndex );
+    dstRule.offset = dstOffsets[tzIndex];
+    stdRule.offset = stdOffsets[tzIndex];
+    strcpy(dstRule.abbrev, dstNames[tzIndex]);
+    strcpy(stdRule.abbrev, stdNames[tzIndex]);
+    tz.setRules(dstRule, stdRule);
+}
+
+void printDateTime(time_t t)
+{
+    Serial << ((day(t)<10) ? "0" : "") << _DEC(day(t));
+    Serial << monthShortStr(month(t)) << _DEC(year(t)) << ' ';
+    Serial << ((hour(t)<10) ? "0" : "") << _DEC(hour(t)) << ':';
+    Serial << ((minute(t)<10) ? "0" : "") << _DEC(minute(t)) << ':';
+    Serial << ((second(t)<10) ? "0" : "") << _DEC(second(t));
+}
+
+// function to return the compile date and time as a time_t value
+time_t compileTime()
+{
+    const time_t FUDGE(10);    //fudge factor to allow for upload time, etc. (seconds, YMMV)
+    const char *compDate = __DATE__, *compTime = __TIME__, *months = "JanFebMarAprMayJunJulAugSepOctNovDec";
+    char compMon[3], *m;
+
+    strncpy(compMon, compDate, 3);
+    compMon[3] = '\0';
+    m = strstr(months, compMon);
+
+    tmElements_t tm;
+    tm.Month = ((m - months) / 3 + 1);
+    tm.Day = atoi(compDate + 4);
+    tm.Year = atoi(compDate + 7) - 1970;
+    tm.Hour = atoi(compTime);
+    tm.Minute = atoi(compTime + 3);
+    tm.Second = atoi(compTime + 6);
+
+    time_t t = makeTime(tm);
+    return t + FUDGE;        //add fudge factor to allow for compile time
+}
+
--- a/libraries/Timezone/examples/Change_TZ_2/Change_TZ_2.ino
+++ b/libraries/Timezone/examples/Change_TZ_2/Change_TZ_2.ino
@@ -0,0 +1,105 @@
+// Arduino Timezone Library Copyright (C) 2018 by Jack Christensen and
+// licensed under GNU GPL v3.0, https://www.gnu.org/licenses/gpl.html
+//
+// Arduino Timezone Library example sketch.
+// Demonstrates changing time zones using an array of Timezone objects.
+// Uses a pushbutton switch to change between the four US continental time zones.
+// Tested with Arduino 1.8.5 and an Arduino Uno.
+//
+// Jack Christensen 02Jan2018
+
+#include <JC_Button.h>          // http://github.com/JChristensen/JC_Button
+#include <Streaming.h>          // http://arduiniana.org/libraries/streaming/
+#include <Timezone.h>           // http://github.com/JChristensen/Timezone
+
+const uint8_t BUTTON_PIN(8);    // connect a button from this pin to ground
+Button btn(BUTTON_PIN);
+
+//Continental US Time Zones
+TimeChangeRule EDT = { "EDT", Second, Sun, Mar, 2, -240 };    //Daylight time = UTC - 4 hours
+TimeChangeRule EST = { "EST", First, Sun, Nov, 2, -300 };     //Standard time = UTC - 5 hours
+Timezone Eastern(EDT, EST);
+TimeChangeRule CDT = { "CDT", Second, Sun, Mar, 2, -300 };    //Daylight time = UTC - 5 hours
+TimeChangeRule CST = { "CST", First, Sun, Nov, 2, -360 };     //Standard time = UTC - 6 hours
+Timezone Central(CDT, CST);
+TimeChangeRule MDT = { "MDT", Second, Sun, Mar, 2, -360 };    //Daylight time = UTC - 6 hours
+TimeChangeRule MST = { "MST", First, Sun, Nov, 2, -420 };     //Standard time = UTC - 7 hours
+Timezone Mountain(MDT, MST);
+TimeChangeRule PDT = { "PDT", Second, Sun, Mar, 2, -420 };    //Daylight time = UTC - 7 hours
+TimeChangeRule PST = { "PST", First, Sun, Nov, 2, -480 };     //Standard time = UTC - 8 hours
+Timezone Pacific(PDT, PST);
+Timezone* timezones[] = { &Eastern, &Central, &Mountain, &Pacific };
+Timezone* tz;                   //pointer to the time zone
+uint8_t tzIndex;                //indexes the timezones[] array
+TimeChangeRule* tcr;            //pointer to the time change rule, use to get TZ abbrev
+
+void setup()
+{
+    // set the system time to UTC
+    // warning: assumes that compileTime() returns US EST
+    // adjust the following line accordingly if you're in another time zone
+    setTime(compileTime() + 300 * 60);
+
+    btn.begin();
+    Serial.begin(115200);
+    tz = timezones[tzIndex];
+}
+
+void loop()
+{
+    // print the time if it's changed
+    static time_t tLast;
+    time_t t = now();
+    if (t != tLast)
+    {
+        tLast = t;
+        printDateTime(t);
+        Serial << " UTC  ";
+        TimeChangeRule* tcr;    //pointer to current time change rule, used to get TZ abbrev
+        printDateTime((*tz).toLocal(t, &tcr));
+        Serial << " " << tcr -> abbrev;
+        Serial << endl;
+    }
+
+    // change the time zone if button pressed
+    btn.read();
+    if (btn.wasPressed())
+    {
+        if ( ++tzIndex >= sizeof(timezones) / sizeof(timezones[0]) ) tzIndex = 0;
+        Serial << "tzIndex " << tzIndex << endl;
+        tz = timezones[tzIndex];
+    }
+}
+
+void printDateTime(time_t t)
+{
+    Serial << ((day(t)<10) ? "0" : "") << _DEC(day(t));
+    Serial << monthShortStr(month(t)) << _DEC(year(t)) << ' ';
+    Serial << ((hour(t)<10) ? "0" : "") << _DEC(hour(t)) << ':';
+    Serial << ((minute(t)<10) ? "0" : "") << _DEC(minute(t)) << ':';
+    Serial << ((second(t)<10) ? "0" : "") << _DEC(second(t));
+}
+
+// function to return the compile date and time as a time_t value
+time_t compileTime()
+{
+    const time_t FUDGE(10);    //fudge factor to allow for upload time, etc. (seconds, YMMV)
+    const char *compDate = __DATE__, *compTime = __TIME__, *months = "JanFebMarAprMayJunJulAugSepOctNovDec";
+    char compMon[3], *m;
+
+    strncpy(compMon, compDate, 3);
+    compMon[3] = '\0';
+    m = strstr(months, compMon);
+
+    tmElements_t tm;
+    tm.Month = ((m - months) / 3 + 1);
+    tm.Day = atoi(compDate + 4);
+    tm.Year = atoi(compDate + 7) - 1970;
+    tm.Hour = atoi(compTime);
+    tm.Minute = atoi(compTime + 3);
+    tm.Second = atoi(compTime + 6);
+
+    time_t t = makeTime(tm);
+    return t + FUDGE;        //add fudge factor to allow for compile time
+}
+
--- a/libraries/Timezone/examples/Clock/Clock.ino
+++ b/libraries/Timezone/examples/Clock/Clock.ino
@@ -0,0 +1,71 @@
+// Arduino Timezone Library Copyright (C) 2018 by Jack Christensen and
+// licensed under GNU GPL v3.0, https://www.gnu.org/licenses/gpl.html
+//
+// Arduino Timezone Library example sketch.
+// Self-adjusting clock for one time zone.
+// TimeChangeRules can be hard-coded or read from EEPROM, see comments.
+// Jack Christensen Mar 2012
+
+#include <Timezone.h>   // https://github.com/JChristensen/Timezone
+
+// US Eastern Time Zone (New York, Detroit)
+TimeChangeRule myDST = {"EDT", Second, Sun, Mar, 2, -240};    // Daylight time = UTC - 4 hours
+TimeChangeRule mySTD = {"EST", First, Sun, Nov, 2, -300};     // Standard time = UTC - 5 hours
+Timezone myTZ(myDST, mySTD);
+
+// If TimeChangeRules are already stored in EEPROM, comment out the three
+// lines above and uncomment the line below.
+//Timezone myTZ(100);       // assumes rules stored at EEPROM address 100
+
+TimeChangeRule *tcr;        // pointer to the time change rule, use to get TZ abbrev
+
+void setup()
+{
+    Serial.begin(115200);
+    setTime(myTZ.toUTC(compileTime()));
+    //setTime(01, 55, 00, 11, 3, 2012);        //another way to set the time (hr,min,sec,day,mnth,yr)
+}
+
+void loop()
+{
+    time_t utc = now();
+    time_t local = myTZ.toLocal(utc, &tcr);
+    Serial.println();
+    printDateTime(utc, "UTC");
+    printDateTime(local, tcr -> abbrev);
+    delay(10000);
+}
+
+// Function to return the compile date and time as a time_t value
+time_t compileTime()
+{
+    const time_t FUDGE(10);     // fudge factor to allow for compile time (seconds, YMMV)
+    const char *compDate = __DATE__, *compTime = __TIME__, *months = "JanFebMarAprMayJunJulAugSepOctNovDec";
+    char chMon[3], *m;
+    tmElements_t tm;
+
+    strncpy(chMon, compDate, 3);
+    chMon[3] = '\0';
+    m = strstr(months, chMon);
+    tm.Month = ((m - months) / 3 + 1);
+
+    tm.Day = atoi(compDate + 4);
+    tm.Year = atoi(compDate + 7) - 1970;
+    tm.Hour = atoi(compTime);
+    tm.Minute = atoi(compTime + 3);
+    tm.Second = atoi(compTime + 6);
+    time_t t = makeTime(tm);
+    return t + FUDGE;           // add fudge factor to allow for compile time
+}
+
+// format and print a time_t value, with a time zone appended.
+void printDateTime(time_t t, const char *tz)
+{
+    char buf[32];
+    char m[4];    // temporary storage for month string (DateStrings.cpp uses shared buffer)
+    strcpy(m, monthShortStr(month(t)));
+    sprintf(buf, "%.2d:%.2d:%.2d %s %.2d %s %d %s",
+        hour(t), minute(t), second(t), dayShortStr(weekday(t)), day(t), m, year(t), tz);
+    Serial.println(buf);
+}
+
--- a/libraries/Timezone/examples/HardwareRTC/HardwareRTC.ino
+++ b/libraries/Timezone/examples/HardwareRTC/HardwareRTC.ino
@@ -0,0 +1,57 @@
+// Arduino Timezone Library Copyright (C) 2018 by Jack Christensen and
+// licensed under GNU GPL v3.0, https://www.gnu.org/licenses/gpl.html
+//
+// Arduino Timezone Library example sketch.
+// Self-adjusting clock for one time zone using an external real-time
+// clock, either a DS1307 or DS3231 (e.g. Chronodot).
+// Assumes the RTC is set to UTC.
+// TimeChangeRules can be hard-coded or read from EEPROM, see comments.
+// Check out the Chronodot at http://www.macetech.com/store/
+//
+// Jack Christensen Aug 2012
+
+#include <DS1307RTC.h>   // https://github.com/PaulStoffregen/DS1307RTC
+#include <Timezone.h>    // https://github.com/JChristensen/Timezone
+
+// US Eastern Time Zone (New York, Detroit)
+TimeChangeRule myDST = {"EDT", Second, Sun, Mar, 2, -240};    //Daylight time = UTC - 4 hours
+TimeChangeRule mySTD = {"EST", First, Sun, Nov, 2, -300};     //Standard time = UTC - 5 hours
+Timezone myTZ(myDST, mySTD);
+
+// If TimeChangeRules are already stored in EEPROM, comment out the three
+// lines above and uncomment the line below.
+//Timezone myTZ(100);       //assumes rules stored at EEPROM address 100
+
+TimeChangeRule *tcr;        //pointer to the time change rule, use to get TZ abbrev
+
+void setup()
+{
+    Serial.begin(115200);
+    setSyncProvider(RTC.get);   // the function to get the time from the RTC
+    if(timeStatus()!= timeSet)
+        Serial.println("Unable to sync with the RTC");
+    else
+        Serial.println("RTC has set the system time");
+}
+
+void loop()
+{
+    time_t utc = now();
+    time_t local = myTZ.toLocal(utc, &tcr);
+    Serial.println();
+    printDateTime(utc, "UTC");
+    printDateTime(local, tcr -> abbrev);
+    delay(10000);
+}
+
+// format and print a time_t value, with a time zone appended.
+void printDateTime(time_t t, const char *tz)
+{
+    char buf[32];
+    char m[4];    // temporary storage for month string (DateStrings.cpp uses shared buffer)
+    strcpy(m, monthShortStr(month(t)));
+    sprintf(buf, "%.2d:%.2d:%.2d %s %.2d %s %d %s",
+        hour(t), minute(t), second(t), dayShortStr(weekday(t)), day(t), m, year(t), tz);
+    Serial.println(buf);
+}
+
--- a/libraries/Timezone/examples/WorldClock/WorldClock.ino
+++ b/libraries/Timezone/examples/WorldClock/WorldClock.ino
@@ -0,0 +1,123 @@
+// Arduino Timezone Library Copyright (C) 2018 by Jack Christensen and
+// licensed under GNU GPL v3.0, https://www.gnu.org/licenses/gpl.html
+//
+// Arduino Timezone Library example sketch.
+// Self-adjusting clock for multiple time zones.
+// Jack Christensen Mar 2012
+//
+// For time zone information:
+// http://www.timeanddate.com/worldclock/
+
+#include <Timezone.h>    // https://github.com/JChristensen/Timezone
+
+// Australia Eastern Time Zone (Sydney, Melbourne)
+TimeChangeRule aEDT = {"AEDT", First, Sun, Oct, 2, 660};    // UTC + 11 hours
+TimeChangeRule aEST = {"AEST", First, Sun, Apr, 3, 600};    // UTC + 10 hours
+Timezone ausET(aEDT, aEST);
+
+// Moscow Standard Time (MSK, does not observe DST)
+TimeChangeRule msk = {"MSK", Last, Sun, Mar, 1, 180};
+Timezone tzMSK(msk);
+
+// Central European Time (Frankfurt, Paris)
+TimeChangeRule CEST = {"CEST", Last, Sun, Mar, 2, 120};     // Central European Summer Time
+TimeChangeRule CET = {"CET ", Last, Sun, Oct, 3, 60};       // Central European Standard Time
+Timezone CE(CEST, CET);
+
+// United Kingdom (London, Belfast)
+TimeChangeRule BST = {"BST", Last, Sun, Mar, 1, 60};        // British Summer Time
+TimeChangeRule GMT = {"GMT", Last, Sun, Oct, 2, 0};         // Standard Time
+Timezone UK(BST, GMT);
+
+// UTC
+TimeChangeRule utcRule = {"UTC", Last, Sun, Mar, 1, 0};     // UTC
+Timezone UTC(utcRule);
+
+// US Eastern Time Zone (New York, Detroit)
+TimeChangeRule usEDT = {"EDT", Second, Sun, Mar, 2, -240};  // Eastern Daylight Time = UTC - 4 hours
+TimeChangeRule usEST = {"EST", First, Sun, Nov, 2, -300};   // Eastern Standard Time = UTC - 5 hours
+Timezone usET(usEDT, usEST);
+
+// US Central Time Zone (Chicago, Houston)
+TimeChangeRule usCDT = {"CDT", Second, Sun, Mar, 2, -300};
+TimeChangeRule usCST = {"CST", First, Sun, Nov, 2, -360};
+Timezone usCT(usCDT, usCST);
+
+// US Mountain Time Zone (Denver, Salt Lake City)
+TimeChangeRule usMDT = {"MDT", Second, Sun, Mar, 2, -360};
+TimeChangeRule usMST = {"MST", First, Sun, Nov, 2, -420};
+Timezone usMT(usMDT, usMST);
+
+// Arizona is US Mountain Time Zone but does not use DST
+Timezone usAZ(usMST);
+
+// US Pacific Time Zone (Las Vegas, Los Angeles)
+TimeChangeRule usPDT = {"PDT", Second, Sun, Mar, 2, -420};
+TimeChangeRule usPST = {"PST", First, Sun, Nov, 2, -480};
+Timezone usPT(usPDT, usPST);
+
+void setup()
+{
+    Serial.begin(115200);
+    
+    // set the system time to UTC
+    // warning: assumes that compileTime() returns US EDT
+    // adjust the following line accordingly if you're in another time zone
+    setTime(compileTime() + 240 * 60);
+}
+
+void loop()
+{
+    time_t utc = now();
+    Serial.println();
+    printDateTime(ausET, utc, "Sydney");
+    printDateTime(tzMSK, utc, " Moscow");
+    printDateTime(CE, utc, "Paris");
+    printDateTime(UK, utc, " London");
+    printDateTime(UTC, utc, " Universal Coordinated Time");
+    printDateTime(usET, utc, " New York");
+    printDateTime(usCT, utc, " Chicago");
+    printDateTime(usMT, utc, " Denver");
+    printDateTime(usAZ, utc, " Phoenix");
+    printDateTime(usPT, utc, " Los Angeles");
+    delay(10000);
+}
+
+// Function to return the compile date and time as a time_t value
+time_t compileTime()
+{
+    const time_t FUDGE(10);     // fudge factor to allow for compile time (seconds, YMMV)
+    const char *compDate = __DATE__, *compTime = __TIME__, *months = "JanFebMarAprMayJunJulAugSepOctNovDec";
+    char chMon[3], *m;
+    tmElements_t tm;
+
+    strncpy(chMon, compDate, 3);
+    chMon[3] = '\0';
+    m = strstr(months, chMon);
+    tm.Month = ((m - months) / 3 + 1);
+
+    tm.Day = atoi(compDate + 4);
+    tm.Year = atoi(compDate + 7) - 1970;
+    tm.Hour = atoi(compTime);
+    tm.Minute = atoi(compTime + 3);
+    tm.Second = atoi(compTime + 6);
+    time_t t = makeTime(tm);
+    return t + FUDGE;           // add fudge factor to allow for compile time
+}
+
+// given a Timezone object, UTC and a string description, convert and print local time with time zone
+void printDateTime(Timezone tz, time_t utc, const char *descr)
+{
+    char buf[40];
+    char m[4];    // temporary storage for month string (DateStrings.cpp uses shared buffer)
+    TimeChangeRule *tcr;        // pointer to the time change rule, use to get the TZ abbrev
+
+    time_t t = tz.toLocal(utc, &tcr);
+    strcpy(m, monthShortStr(month(t)));
+    sprintf(buf, "%.2d:%.2d:%.2d %s %.2d %s %d %s",
+        hour(t), minute(t), second(t), dayShortStr(weekday(t)), day(t), m, year(t), tcr -> abbrev);
+    Serial.print(buf);
+    Serial.print(' ');
+    Serial.println(descr);
+}
+
--- a/libraries/Timezone/examples/WriteRules/WriteRules.ino
+++ b/libraries/Timezone/examples/WriteRules/WriteRules.ino
@@ -0,0 +1,29 @@
+// Arduino Timezone Library Copyright (C) 2018 by Jack Christensen and
+// licensed under GNU GPL v3.0, https://www.gnu.org/licenses/gpl.html
+//
+// Arduino Timezone Library example sketch.
+// Write TimeChangeRules to EEPROM.
+// Jack Christensen Mar 2012
+
+#include <Timezone.h>   // https://github.com/JChristensen/Timezone
+
+// US Eastern Time Zone (New York, Detroit)
+TimeChangeRule usEdt = {"EDT", Second, Sun, Mar, 2, -240};    // UTC - 4 hours
+TimeChangeRule usEst = {"EST", First, Sun, Nov, 2, -300};     // UTC - 5 hours
+Timezone usEastern(usEdt, usEst);
+
+void setup()
+{
+    pinMode(13, OUTPUT);
+    usEastern.writeRules(100);    // write rules to EEPROM address 100
+}
+
+void loop()
+{
+    // fast blink to indicate EEPROM write is complete
+    digitalWrite(13, HIGH);
+    delay(100);
+    digitalWrite(13, LOW);
+    delay(100);
+}
+
--- a/libraries/Timezone/examples/tzTest/tzTest.ino
+++ b/libraries/Timezone/examples/tzTest/tzTest.ino
@@ -0,0 +1,85 @@
+// Arduino Timezone Library Copyright (C) 2018 by Jack Christensen and
+// licensed under GNU GPL v3.0, https://www.gnu.org/licenses/gpl.html
+//
+// Arduino Timezone Library example sketch.
+// Sketch to verify operation of Timezone library.
+// Jack Christensen 14Nov2018
+
+#include <Timezone.h>   // https://github.com/JChristensen/Timezone
+#include <TimeLib.h>    // https://github.com/PaulStoffregen/Time
+
+// New Zealand Time Zone
+TimeChangeRule nzSTD = {"NZST", First, Sun, Apr, 3, 720};   // UTC + 12 hours
+TimeChangeRule nzDST = {"NZDT", Last, Sun, Sep, 2, 780};    // UTC + 13 hours
+Timezone nz(nzDST, nzSTD);
+
+// US Eastern Time Zone (New York, Detroit)
+TimeChangeRule etDST = {"EDT", Second, Sun, Mar, 2, -240};  // Daylight time = UTC - 4 hours
+TimeChangeRule etSTD = {"EST", First, Sun, Nov, 2, -300};   // Standard time = UTC - 5 hours
+Timezone et(etDST, etSTD);
+
+void setup()
+{
+    Serial.begin(115200);
+
+    // New Zealand
+    printTimes( 1,  4, 2018, nzSTD.hour, nzDST.offset, nz); // day, month, year, hour, offset, tz
+    printTimes(30,  9, 2018, nzDST.hour, nzSTD.offset, nz);
+    printTimes( 7,  4, 2019, nzSTD.hour, nzDST.offset, nz);
+    printTimes(29,  9, 2019, nzDST.hour, nzSTD.offset, nz);
+    printTimes( 5,  4, 2020, nzSTD.hour, nzDST.offset, nz);
+    printTimes(27,  9, 2020, nzDST.hour, nzSTD.offset, nz);
+
+    // US Eastern
+    printTimes(11,  3, 2018, etDST.hour, etSTD.offset, et); // day, month, year, hour, offset, tz
+    printTimes( 4, 11, 2018, etSTD.hour, etDST.offset, et);
+    printTimes(10,  3, 2019, etDST.hour, etSTD.offset, et);
+    printTimes( 3, 11, 2019, etSTD.hour, etDST.offset, et);
+    printTimes( 8,  3, 2020, etDST.hour, etSTD.offset, et);
+    printTimes( 1, 11, 2020, etSTD.hour, etDST.offset, et);
+}
+
+void loop() {}
+
+// print corresponding UTC and local times "n" seconds before and after the time change.
+// h is the hour to change the clock using the *current* time (i.e. before the change).
+// offset is the utc offset in minutes for the time *after* the change.
+void printTimes(uint8_t d, uint8_t m, int y, uint8_t h, int offset, Timezone tz)
+{
+    const time_t n(3);      // number of times to print before and after the time change
+    tmElements_t tm;
+    tm.Hour = h;
+    tm.Minute = 0;
+    tm.Second = 0;
+    tm.Day = d;
+    tm.Month = m;
+    tm.Year = y - 1970;     // offset from 1970
+    time_t utc = makeTime(tm) - offset * SECS_PER_MIN - n;
+
+    Serial.print(F("\n-------- "));
+    Serial.print(monthShortStr(m));
+    Serial.print('-');
+    Serial.print(y);
+    Serial.print(F(" time change --------\n"));
+
+    for (uint16_t i=0; i<n*2; i++)
+    {
+        TimeChangeRule *tcr;    // pointer to the time change rule, use to get TZ abbrev
+        time_t local = tz.toLocal(utc, &tcr);
+        printDateTime(utc, "UTC = ");
+        printDateTime(local, tcr -> abbrev);
+        Serial.println();
+        ++utc;
+    }
+}
+
+// format and print a time_t value, with a time zone appended.
+void printDateTime(time_t t, const char *tz)
+{
+    char buf[32];
+    char m[4];    // temporary storage for month string (DateStrings.cpp uses shared buffer)
+    strcpy(m, monthShortStr(month(t)));
+    sprintf(buf, "%.2d:%.2d:%.2d %s %.2d %s %d %s",
+        hour(t), minute(t), second(t), dayShortStr(weekday(t)), day(t), m, year(t), tz);
+    Serial.print(buf);
+}