www.hamgadgets.com
2014-01-17
ID-O-Matic III
33
Adding GPS Timing
Your ID-O-Matic III has an internal time of day clock that can be used to synchronize beacon
transmissions to the real time. However, there is no backup for this clock in the event of a power
failure, and the long term accuracy is not guaranteed. Timing drift of several seconds or even a
few minutes per month or more can be expected, especially with large variations in temperature.
If you want long term timing accuracy, a GPS time source may be connected to the ID-O-Matic
III. Standard NMEA serial data is used to set the real-time clock according to GPS time. If the
GPS is installed, the real-time clock will always be set to UTC (Zulu) time. There is no
provision for setting the time zone or handling DST changes.
Once the GPS is attached there is no further configuration needed. The ID-O-Matic will
automatically listen for GPS data/time messages and set the internal real-time clock according to
GPS time. In order to reduce CPU workload, once the GPS time is set the clock is only
synchronized periodically. This is still far more often than would be required to keep the time
set even under the worst conditions.
The three pin header marked “AUX” near U1 can be used to connect to the GPS receiver.
Caution:
The GPS data connection must be TTL, not RS-232.
Make sure the GPS data signal
does not exceed 5V. Failure to do so will cause permanent damage to the ID-O-Matic III
processor!
Summary of Contents for ID-O-Matic III
Page 1: ...www hamgadgets com 2014 01 17 HamGadgets ID O Matic III Assembly Setup and Use Guide ...
Page 26: ...www hamgadgets com 2014 01 17 ID O Matic III 26 PCB Layout Schematic Rev C ...
Page 27: ...www hamgadgets com 2014 01 17 ID O Matic III 27 PCB Layout Schematic Rev D ...
Page 32: ...www hamgadgets com 2014 01 17 ID O Matic III 32 ...
