rstephan/timezoneinfo

Arduino library to convert utc to local time (timezone) using tzdata from linux.

TimeZoneInfo

With the use of the tzdata your project can now run in local time. Getting UTC time is easy, (GPS, NTP, ..) but local time is not. GMT plus x works mostly only for half of a year. (Daylight-Saving-Time) DST is evil! You can't calculate it! This is why linux uses a database to make DST work. So, why not using it for your Arduino? It is a bit "heavy", prox. 4kB for the database of one location + the code to make it work.

This is a 32-Bit version! Year 2038 will come fast!

Example

UtcToLocal

TimeZoneInfo-Test

Berlin
UTC=00:59:57 27.03.2016
LOC=01:59:57 27.03.2016 CET

UTC=00:59:58 27.03.2016
LOC=01:59:58 27.03.2016 CET

UTC=00:59:59 27.03.2016
LOC=01:59:59 27.03.2016 CET

UTC=01:00:00 27.03.2016
LOC=03:00:00 27.03.2016 DST CEST

UTC=01:00:01 27.03.2016
LOC=03:00:01 27.03.2016 DST CEST

UTC=01:00:02 27.03.2016
LOC=03:00:02 27.03.2016 DST CEST


Los_Angeles
UTC=08:59:57 06.11.2016
LOC=01:59:57 06.11.2016 DST PDT

UTC=08:59:58 06.11.2016
LOC=01:59:58 06.11.2016 DST PDT

UTC=08:59:59 06.11.2016
LOC=01:59:59 06.11.2016 DST PDT

UTC=09:00:00 06.11.2016
LOC=01:00:00 06.11.2016 PST

UTC=09:00:01 06.11.2016
LOC=01:00:01 06.11.2016 PST

UTC=09:00:02 06.11.2016
LOC=01:00:02 06.11.2016 PST

Done.

Database

Getting the tzfile-database is easy in linux.

Usualy these files are in /usr/share/zoneinfo.

Converting to a C-header file:

1. With the "build-in" xxd-tool

   cd /usr/share/zoneinfo/Europe
   # Add PROGMEM, if not your are running out of RAM.
   xxd -i Berlin | sed -e 's/unsigned char/unsigned char PROGMEM/' > ~/Arduino/MyProject/Berlin.h
   

2. With my binhex-Tool

   ./binhex -f /usr/share/zoneinfo/America/Los_Angeles -p ZI_LA > ~/Arduino/MyProject/America_Los_Angeles.h
   

License

GPLv2