GPS Receiver
A1037-A
10.4 1PPS pin (1 pulse per second pin)
The 1PPS pin is an output pin.
In addition to precise positioning, GPS also allows for accurate timing due to the
synchronized atomic clocks in the GPS satellites. While the current date and time is
transmitted in NMEA sentences, an exact and accurate timing signal is provided via
the 1PPS pin of the A1037 modules.
10.5 Reset Signal
The nRST pin is an input pin.
The nRST pin can be used to generate a reset on the A1037-A module. Resetting
the module will result in a restart of the complete firmware. All information stored in
SRAM will still be valid.
10.6 Battery Back-up
This application note describes on how to back-up the RTC and the SRAM of the
GPS receiver module. The basic of the first examples is to provide a back-up by a
separate battery or a “supercap”. Here it has to be considered that the RTC is only
backed as long as the voltage on the Vbak pin is higher than 2.9V.
While the “supercap” is charged thru the module during normal operation, the bat-
tery (primary cell) is decoupled thru a diode!
Figure 14: Application note: Module back-up
An alternative to this solution is to switch the supply voltage from the Vcc pin to
the Vbak pin. Care needs to be taken that the there is no voltage outage during
the switch-over phase!
V2.0 - 03/07
User’s Manual
Page 25 of 29
