WiFi1500CF Plug-In Hardware User Guide JA03-UM-WiFi
Page 11 Rev: P00 Date: 03/13/14
© Copyright 2014 Janus Remote Communications
Specifications subject to change without notice
All Rights Reserved See website for latest revision. Not intended for life support applications.
4. GPS Module (Optional)
The Telit JN3 GPS receiver provides position and timing information using standard NMEA (National Marine
Electronics Association) strings over a UART interface. In addition, a 1PPS signal is available to provide an accurate
timing mark when a high quality fix is available. A complete description of this module is beyond the scope of this
document. Detailed hardware and operational information can be found in the JN3 GPS receiver documentation
listed in the Applicable Documents section.
4.1 GPS Module Connections
The connections between the JN3 module and the WiFi1500CF pins are shown in the table below.
JN3
WiFi1500CF JN3
WiFi1500CF
Pin
Name
Interface
Pin
Name
Pin Name
Interface
Pin Name
1
NC
N/C
13
GND
GND
2
NC
N/C
14
NC
N/C
3
1PPS
Level Shifter
8
1PPS
15
NC
N/C
4
EXT_INT
N/C
16
NC
N/C
5
NC
N/C
17
NC
N/C
6
NC
N/C
18
SDA2
N/C
7
BOOT
Internal
1
19
SCL2
N/C
8
NC
N/C
20
TX
Level Shifter
34
GPS_X
9
VCC_IN
3.3V
21
RX
Level Shifter
33
GPS_RX
10
GND
GND
22
VBATT
N/C
11
RF_IN
u.FL Connector
23
VCC_IN
3.3V
12
GND
GND
24
GND
GND
N/C – Not Connected
1 The GS1500M VOUT_1V8 pin can be jumpered to the JN3 module’s BOOT pin. See the Configuration Option section.
Antenna
A u.FL connector is provided for connecting a GPS antenna. This connector is located on the top surface of the
WiFi1500CF board at the pin 25 corner. This connector also provides a 3.3 volt bias at the antenna connector for
powering remote amplifiers that are often built in to GPS antennas.
Do not short the antenna output
UART interface
The UART on the JN3 GPS module is brought out through a level shifter and support is provided for the TX and
RX signals. The default setting for the JN3 GPS UART interface is 4800 baud, 8 bit characters with no parity bits
and one stop bit (8N1).
The JN3 GPS module provides a NMEA interface on the UART; more information can be found in the ‘JN3
Product Description’ document listed in the Applicable Documents section.
1PPS output
A 1PPS (one pulse-per-second) output is available from the GPS receiver when a high quality (3D) position fix is
obtained. The pulse width is 200 ms and the leading edge of the pulse is synchronous with one second timing.
The 1PPS signal appears on the WiFi1500CF pin that is designated as the GS1500M UART0 DCD pin. The DCD
pin is a standard 1PPS interface on serial connections to hosts running NTP (network timing protocol) applications.
For a full implementation, the JN3 UART TX and RX signals should also appear on the UART0 interface. This can be
accomplished by changes to the configuration jumpers. See the Configuration Options section.
