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Copernicus GPS Receiver 45
INTERFACE CHARACTERISTICS 3
Table 3.2 Antenna Status Truth Table
When using a passive antenna with the SHORT and OPEN pins floating, the receiver
will report an open condition. If a normal condition from the receiver is desired when
using a passive antenna, set the logic levels of the SHORT pin High and the OPEN
pin Low.
XRESET
This logic-level, active low input is used to issue hardware or power-on reset to the
module. It may be connected to external logic or to a processor to issue reset. To reset
the module, take this pin low for at least 100 microseconds. This pin must be tied to
VCC with a resistance of less than 10 K Ohms if not used.
The hardware reset deletes all the information saved in SRAM (position time,
almanac, ephemeris and customers' user set configurations if not previously saved in
non-volatile Flash memory) and restarts the Copernicus receiver. See Absolute
Minimum and Maximum Limits, page 37 for pin threshold values.
VCC
This is the primary voltage supply pin for the module. This pin also provides power
during Standby Mode (Backup Mode). To setup separate power supplies for main
power and Standby Mode (Backup Mode) power, an external diode-pair must be
provided.
XSTANDBY
This logic level input is used to control the RUN/STANDBY state of the module. If
this signal is High, the unit will run normally. If this signal is Low, the unit will go to
“STANDBY” mode. See Absolute Minimum and Maximum Limits, page 37 for pin
threshold values.
PPS
Pulse-per-second. This logic level output provides a 1 Hz timing signal to external
devices. The positive going 4.2 usec pulse width is controllable by TSIP packet 0x8E-
4F. The cable delay and polarity is controllable by TSIP packet 0x8E-4A. The PPS
mode is set by TSIP packet 0x35. This output meets the input/output pin threshold
specifications (see Absolute Minimum and Maximum Limits, page 37.)
Condition of logic signals
ANTENNA REPORTS SHORT OPEN
Antenna Open Reported 1 1
Antenna Normal Reported 1 0
Antenna Shorted Reported 0 0
Undefined 0 1