Add constructor for time zones that do not observe daylight time.

Update example sketch.

README.md

@@ -67,15 +67,15 @@ TimeChangeRule usEDT = {"EDT", Second, Sun, Mar, 2, -240};  //UTC - 4 hours
 TimeChangeRule usEST = {"EST", First, Sun, Nov, 2, -300};   //UTC - 5 hours
 ```
 
-For a time zone that does not change to daylight/summer time, pass the same rule twice to the constructor, for example:  
-`Timezone usAZ(usMST, usMST);`
-
 ## Coding Timezone objects
-There are two ways to define **Timezone** objects.
+There are three ways to define **Timezone** objects.
 
 By first defining **TimeChangeRule**s (as above) and giving the daylight time rule and the standard time rule (assuming usEDT and usEST defined as above):  
 `Timezone usEastern(usEDT, usEST);`
 
+For a time zone that does not change to daylight/summer time, pass a single rule to the constructor. For example:  
+`Timezone usAZ(usMST, usMST);`
+
 By reading rules previously stored in EEPROM.  This reads both the daylight and standard time rules previously stored at EEPROM address 100:  
 `Timezone usPacific(100);`
 

examples/WorldClock/WorldClock.ino

@@ -15,6 +15,10 @@ 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
@@ -27,42 +31,47 @@ Timezone UK(BST, GMT);
 
 // UTC
 TimeChangeRule utcRule = {"UTC", Last, Sun, Mar, 1, 0};     // UTC
-Timezone UTC(utcRule, utcRule);
+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, dowSunday, Mar, 2, -300};
-TimeChangeRule usCST = {"CST", First, dowSunday, Nov, 2, -360};
+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, dowSunday, Mar, 2, -360};
-TimeChangeRule usMST = {"MST", First, dowSunday, Nov, 2, -420};
+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, usMST);
+Timezone usAZ(usMST);
 
 // US Pacific Time Zone (Las Vegas, Los Angeles)
-TimeChangeRule usPDT = {"PDT", Second, dowSunday, Mar, 2, -420};
-TimeChangeRule usPST = {"PST", First, dowSunday, Nov, 2, -480};
+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);
-    setTime(usET.toUTC(compileTime()));
+
+    // 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");

library.properties

@@ -1,5 +1,5 @@
 name=Timezone
-version=1.1.3
+version=1.2.0
 author=Jack Christensen <[email protected]>
 maintainer=Jack Christensen <[email protected]>
 sentence=Arduino library to facilitate time zone conversions and automatic daylight saving (summer) time adjustments.

src/Timezone.cpp

@@ -21,6 +21,16 @@ Timezone::Timezone(TimeChangeRule dstStart, TimeChangeRule stdStart)
     m_std = stdStart;
 }
 
+/*----------------------------------------------------------------------*
+ * Create a Timezone object for a zone that does not observe            *
+ * daylight time.                                                       *
+ *----------------------------------------------------------------------*/
+Timezone::Timezone(TimeChangeRule stdTime)
+{
+    m_dst = stdTime;
+    m_std = stdTime;
+}
+
 #ifdef __AVR__
 /*----------------------------------------------------------------------*
  * Create a Timezone object from time change rules stored in EEPROM     *

src/Timezone.h

@@ -36,6 +36,7 @@ class Timezone
 {
     public:
         Timezone(TimeChangeRule dstStart, TimeChangeRule stdStart);
+        Timezone(TimeChangeRule stdTime);
         Timezone(int address);
         time_t toLocal(time_t utc);
         time_t toLocal(time_t utc, TimeChangeRule **tcr);