ATR0625-DK1 ATMEL [ATMEL Corporation], ATR0625-DK1 Datasheet - Page 12

• Manufacturer Part Number: ATR0625-DK1
• Description: GPS Baseband Processor SuperSense
• Manufacturer: ATMEL [ATMEL Corporation]

3.3.4
3.3.5
12
ATR0625 [Preliminary]
USB Power Mode
Active Antenna Supervisor
For correct response to the USB host queries, the device has to know its power mode. This is
configured via GPSMODE7. If set to bus powered, an upper current limit of 100 mA is reported
to the USB host; that is, the device classifies itself as a “low-power bus-powered function” with
no more than one USB power unit load.
Table 3-12.
The two pins P0/NANTSHORT and P15/ANTON plus one pin of P25/NAADET0/MISO or
P14/NAADET1 are always initialized as general purpose I/Os and used as follows:
Table 3-13.
Pin
P0/NANTSHORT
P25/NAADET0/
MISO or
P14/NAADET1
P15/ANTON
GPSMODE7 (Reset = PU) Description
• P15/ANTON is an output which can be used to switch on and off antenna power supply.
• Input P0/NANTSHORT will indicate an antenna short circuit, i.e. zero DC voltage at the
• Input P25/NAADET0/MISO or P14/NAADET1 will indicate a DC current into the antenna. In
antenna, to the firmware. If the antenna is switched off by output P15/ANTON, it is
assumed that also input P0/NANTSHORT will signal zero DC voltage, i.e. switch to its
active low state.
case of short circuit, both P0 and P25/P14 will be active, i.e. at low level. If the antenna is
switched off by output P15/ANTON, it is assumed that also input P25/NAADET0/MISO will
signal zero DC current, i.e. switch to its active low state. Which pin is used as NAADET
(P14 or P25) depends on the settings of GPSMODE11 and GPSMODE10 (see
on page
13).
0
1
USB Power Modes
Pin Usage of Active Antenna Supervisor
Usage
NANTSHORT
NAADET
ANTON
USB device is bus-powered (max. current limit 100 mA)
USB device is self-powered (Default ROM value)
Meaning
Active antenna short circuit detection
High = No antenna DC short circuit present
Low = Antenna DC short circuit present
Active antenna detection input
High = No active antenna present
Low = Active antenna is present
Active antenna power on output
High = Power supply to active antenna is switched on
Low = Power supply to active antenna is switched off
4925A–GPS–02/06
Table 3-14