Add support for fractional time zone offsets

Author: PaulZC

Firmware/OpenLog_Artemis/menuTimeStamp.ino

@@ -152,7 +152,7 @@ void menuTimeStamp()
       else if (incoming == 9)
       {
         SerialPrint(F("Enter the local hour offset from UTC (-12 to 14): "));
-        int offset = getNumber(menuTimeout); //Timeout after x seconds
+        float offset = (float)getDouble(menuTimeout); //Timeout after x seconds
         if (offset < -12 || offset > 14)
           SerialPrintln(F("Error: Offset is out of range"));
         else

Firmware/OpenLog_Artemis/settings.h

@@ -374,7 +374,7 @@ struct struct_settings {
   bool logA13 = false;
   bool logA32 = false;
   bool logAnalogVoltages = true;
-  int  localUTCOffset = 0; //Default to UTC because we should
+  float localUTCOffset = 0; // Default to UTC because we should. Support offsets in 15 minute increments.
   bool printDebugMessages = false;
 #if(HARDWARE_VERSION_MAJOR == 0)
   bool powerDownQwiicBusBetweenReads = false; // For the SparkX (black) board: default to leaving the Qwiic power enabled during sleep and powerDown to prevent a brown-out.

Firmware/OpenLog_Artemis/timeStamp.ino

@@ -49,7 +49,8 @@ void getTimeString(char timeStringBuffer[])
     char rtcMin[3];
     char rtcSec[3];
     char rtcHundredths[3];
-    char timeZone[4];
+    char timeZoneH[4];
+    char timeZoneM[4];
     if (adjustedHour < 10)
       sprintf(rtcHour, "0%d", adjustedHour);
     else
@@ -69,20 +70,27 @@ void getTimeString(char timeStringBuffer[])
     if (settings.localUTCOffset >= 0)
     {
       if (settings.localUTCOffset < 10)
-        sprintf(timeZone, "+0%d", settings.localUTCOffset);
+        sprintf(timeZoneH, "+0%d", (int)settings.localUTCOffset);
       else
-        sprintf(timeZone, "+%d", settings.localUTCOffset);
+        sprintf(timeZoneH, "+%d", (int)settings.localUTCOffset);
     }
     else
     {
       if (settings.localUTCOffset <= -10)
-        sprintf(timeZone, "-%d", 0 - settings.localUTCOffset);
+        sprintf(timeZoneH, "-%d", 0 - (int)settings.localUTCOffset);
       else
-        sprintf(timeZone, "-0%d", 0 - settings.localUTCOffset);
+        sprintf(timeZoneH, "-0%d", 0 - (int)settings.localUTCOffset);
     }
+    int tzMins = (int)((settings.localUTCOffset - (float)((int)settings.localUTCOffset)) * 60.0);
+    if (tzMins < 0)
+      tzMins = 0 - tzMins;
+    if (tzMins < 10)
+      sprintf(timeZoneM, ":0%d", tzMins);
+    else
+      sprintf(timeZoneM, ":%d", tzMins);
     if ((settings.logDate) && (settings.dateStyle == 3))
     {
-      sprintf(rtcTime, "%s:%s:%s%s:00,", rtcHour, rtcMin, rtcSec, timeZone);
+      sprintf(rtcTime, "%s:%s:%s%s%s,", rtcHour, rtcMin, rtcSec, timeZoneH, timeZoneM);
       strcat(timeStringBuffer, rtcTime);      
     }
     if (settings.logTime)
@@ -142,18 +150,32 @@ void getGPSDateTime(int &year, int &month, int &day, int &hour, int &minute, int
   //Do it twice - to make sure the data is fresh
   getUbloxDateTime(year, month, day, hour, minute, second, millisecond, dateValid, timeValid);
 
-  adjustToLocalDateTime(year, month, day, hour, settings.localUTCOffset);
+  adjustToLocalDateTime(year, month, day, hour, minute, settings.localUTCOffset);
 }
 
 //Given the date and hour, calculate local date/time
 //Adjust the hour by local hour offset
 //Adjust the hour by DST as necessary
 //Adjust the date as necessary
 //Leap year is taken into account but does not interact with DST (DST happens later in March)
-void adjustToLocalDateTime(int &year, int &month, int &day, int &hour, int localUTCOffset) {
+void adjustToLocalDateTime(int &year, int &month, int &day, int &hour, int &minute, float localUTCOffset) {
 
   //Apply any offset to UTC
-  hour += localUTCOffset;
+  hour += (int)localUTCOffset;
+
+  //Apply minutes offset
+  int tzMins = (int)((localUTCOffset - (float)((int)localUTCOffset)) * 60.0);
+  minute += tzMins;
+  if (minute >= 60)
+  {
+    hour += 1;
+    minute -= 60;
+  }
+  else if (minute < 0)
+  {
+    hour -= 1;
+    minute += 60;
+  }
 
   //If the adjusted hour is outside 0 to 23, then adjust date as necessary
   correctDate(year, month, day, hour);