User's Manual

GE/GC864-QUAD V2 and GE864-GPS Hardware User Guide
1vv0300915 Rev.2 – 2011-06-15
Reproduction forbidden without Telit Communications S.p.A. written authorization - All Rights
Reserved. Page 35 of 97
- Assert a pulse on the GPS_ON_OFF input every seconds
until GPS starts indicating a high on GPS_WAKEUP output
or generation of serial messages.
The GPS starts after asserting a rising edge pulse on
GPS_ON_OFF input and when high level persists for at least
three cycles of RTC clock. Before asserting another pulse to
GPS_ON_OFF input, the host controller must put it at low state
and hold it low for at least three cycles of the RTC clock.
The GPS_WAKEUP output goes high indicating the GPS is working.
As suggested in chapter 4.1.1 (Pin Out) do not leave the
GPS_ON_OFF (ball J4) input pin floating. It’ suggested to
connect it to a pull-down resistor (e.g.: 100k)
5.4.2. GPS Shutdown
When GPS is working, a pulse on the GPS_ON_OFF input origins
the GPS shutdown sequence.
As explained for power-up, a rising edge pulse followed by an
high level logic for at least three cycles of RTC clock is
recognized as an GPS_ON_OFF pulse. Before asserting another
pulse to GPS_ON_OFF input, the host controller must put it at
low state and hold it low for at least three cycles of the RTC
clock.
The shutdown sequence may take anywhere from 10ms to 900ms,
depending on operation in progress.
Avoid any abrupt, uncontrolled removal of power (VBATT) while
GPS is operating. Before removing the supply from the module,
perform the shutdown sequence. Performance degradation may be
the consequences of any uncontrolled removal of main power.