Global Sat ET-314 User manual

ET-314
Page1of19
Version 1.2
GPS Engine Board ET-314
Version 1.2
06/22/2007
Globalsat Technology Corporation Headquarters (Far East Century Park)
16F., No. 186, Jian-Yi Road, Chung-Ho City, Taipei Hsien 235, Taiwan
Tel: [phone]/ Fax: [phone]
E-mail : [e-mail]
Website: www.globalsat.com.tw

ET-314
The Specifications are subject to be changed without notice. Copyright ©2007, GlobalSat Technology.
Page 2 of 19
Version 1.2
1. Product Information
Product Name: ET-314
Product Description:
ET-314 is a compact, high performance, and low power consumption GPS engine board. It uses SiRF
Star III chipset which can track up to 20 satellites at a time and perform fast TTFF in weak signal
environments. ET-314 is suitable for the following applications:
‧ Automotive navigation
‧ Personal positioning
‧ Fleet management
‧ Marine navigation
Product Features:
SiRF star III high performance GPS Chipset
Very high sensitivity (Tracking Sensitivity: -159 dBm)
Extremely fast TTFF (Time To First Fix) at low signal level
Two serial ports
4Mb flash
Compact size (25.4mm * 25.4 mm * 3.3mm) suitable for space-sensitive application
One size component, easy to mount on another PCB board
Support NMEA 0183 and SiRF binary protocol
Product Specifications
GPS Receiver
Chipset SiRF StarⅢ
Frequency L1, 1575.42 MHz
Code C/A Code
Protocol NMEA 0183 v2.2
Default:GGA,GSA,GSV,RMC
Support:VTG,GLL,ZDA)
SiRF binary and NMEA Command
Available Baud Rate 4,800 to 57,600 bps adjustable
Channels 20
Flash 4Mbit

ET-314
The Specifications are subject to be changed without notice. Copyright ©2007, GlobalSat Technology.
Page 3 of 19
Version 1.2
Sensitivity Tracking:-159dBm
Cold Start 42 seconds, average
Warm Start 38 seconds, average
Hot Start 1 second, average
Reacquisition 0.1 second, average
Accuracy Position: 10 meters, 2D RMS
5 meters, 2D RMS, WAAS enabled
Velocity: 0.1 m/s
Time: 1us synchronized to GPS time
Maximum Altitude ＜18,000 meter
Maximum Velocity ＜515 meter/second
Maximum Acceleration ＜4G
Update Rate 1 Hz
DGPS WAAS, EGNOS, MSAS
Datum WGS-84
Interface
I/O Pins 2 serial ports
Physical Characteristic
Type 30-pin stamp holes
Dimensions 25.4 mm * 25.4 mm * 3.3 mm
DC Characteristics
Power Supply 3.3Vdc ± 5%
Backup Voltage 2.0 ~ 3.6Vdc ± 10%
Power Consumption Acquisition: 42mA
Tracking: 25mA
Environmental Range
Humidity Range 5% to 95% non-condensing
Operation Temperature -40℃ to 85℃
Storage Temperature -40℃ to 125℃

ET-314
The Specifications are subject to be changed without notice. Copyright ©2007, GlobalSat Technology.
Page 4 of 19
Version 1.2
2. Technical Information
Block Diagram
Module Pin Assignment:

ET-314
The Specifications are subject to be changed without notice. Copyright ©2007, GlobalSat Technology.
Page 5 of 19
Version 1.2
Pin Signal Name I/O Description
1 VCC I DC Supply Voltage input
2 GND G Ground
3 Boot select I Boot mode
4 RXA I Serial port A
5 TXA O Serial portA
6 TXB O Serial port B
7 RXB I Serial port B
8 GPIO14 I/O General –purpose I/O
9 RF_ON
10 GND G Digital Ground
11
16 GND_A G Analog Ground
17 RF_IN I GPS Signal input
18 GND_A G Analog Ground
19 V_ANT_IN I Active Antenna Bias voltage
20 VCC_RF O Supply Antenna Bias voltage
21 V_BAT I Backup voltage supply
22 Reset I Reset (Active low)
23 GPIO10 I/O General purpose I/O
24 GPIO1 I/O General purpose I/O
25 GPIO5 I/O General purpose I/O
26 GPIO0 I/O General purpose I/O
(support continuous power mode only)
27 GPIO13 I/O General purpose I/O
28 GPIO15 I/O General purpose I/O
29 PPS O One pulse per second
30 GND G Digital Ground
Definition of Pin assignment
VCC
This is the main DC supply for a 3.3V +- 5% DC input power module board.
GND
GND provides the ground for digital pa rt.

ET-314
The Specifications are subject to be changed without notice. Copyright ©2007, GlobalSat Technology.
Page 6 of 19
Version 1.2
Boot select
Set this pin t o high for programming f lash.
RXA
This is t he main receiver channel and is used t o receive so ft ware commands to the board from
SIRFdemo sof t ware or from user written sof t ware.
PS:
Pull up if not used.
RXB
This is t he auxiliary receiving channel and is used to input di ff erential corrections t o the board to
enable DGPS navigation.
PS:
Pull up if not used.
TXA
This is the main transmitting channel and is used to output navigation and
measuremen
t data to SiRFdemo or user written software.
TXB
For user’s application (not currently used).
RF_ON
This pin indicates state of RF voltage.
RF_IN
This pin receiver signal of GPS analog .due to the RF characteristics of the signal the design has
to certain criteria. The line on the PCB from the antenna(or antenna connector) has to be a
controlled microstrip line at 50 Ω
V_ANT_IN
This pin is reserved an external DC power supply for active antenna.
If
using 3.3V active antenna, pin 19 has to be connected to pin 20.
If the bias voltage of active isn’t 3.3V
,you can input bias voltage of you need to this pin.
VCC_RF
This pin provides DC voltage 3.3 for active antenna. Reset

ET-314
The Specifications are subject to be changed without notice. Copyright ©2007, GlobalSat Technology.
Page 7 of 19
Version 1.2
This pin provides an active-low rese t input to the board. It causes the board to reset and start
searching for satellites. If not utilized, it may be left open.
PPS
This pin provides one pulse-per-second output from the board, which is
synchronized
to GPS time. This is not available in Trickle Power mode .
Backup battery (V_BAT)
This is the battery backup input that powers the SRAM and RTC when main power is removed.
Typical current draw is 15uA. Without an external backup battery, the module/engine board will
execute a cold star after every turn on. To achieve the faster start-up offered by a hot or warm start,
a battery backup must be connected. The battery voltage should be between 2.0v and 5.0v.
Without an external backup battery or super cap , the TMP will execute a cold start after every
power on . To achieve the faster start-up offered by a hot or warm start, either a battery backup
must be connected or a super cap installed.
To maximize battery lifetime, the battery voltage should not exceed the supply voltage and
should be between 2.5V and 3.6V .
With the super cap (B1) installed, and after at least ten minutes of continuous operation, the
data retention is about seven hours.
Note that even though all other components are rated at –30 t o +85 deg C, a typical super cap is
specified over a temperature range of –25 to +70 deg C and a typical rechargeable Lithium battery
is over –20 to +70 deg C.
GPIO Functions
Several I/Os are connected to the digital interface connector for custom
applications
.

ET-314
The Specifications are subject to be changed without notice. Copyright ©2007, GlobalSat Technology.
Page 8 of 19
Version 1.2
Application Circuit
GPIO_0
ACTIVE ANT
1
2
GPIO_14
V_BAT
GPIO_5
TXA
TXB
GPIO_10
VCC
VCC_RF
1PPS
RXB
V_ANT
GPIO_1
GPIO_15
50 ohm microstrip line
VCC
R1
10k
1 2
R2
10k
1 2
GPIO_13
RESET
RXA
BOOT
U1 GPS
6
30
27
28
29
5
4
3
2
1
7
8
9
10
11
12
13
14
15
26
25
24
23
22
21
20
19
18
17
16
TXB
GND
GPIO_13
GPIO_15
1PPS
TXA
RXA
Bootselect
GND
VCC
RXB
GPIO_14
RF_ON
GND
A_GND
A_GND
A_GND
A_GND
A_GND
GPIO_0
GPIO_5
GPIO_1
GPIO_10
NRESET
V_BAT
VCC_RF
V_ANT
A_GND
RF_IN
A_GND
R4
10k
1 2
R3
10k
1 2
(1) Ground Planes:
ET-314 GPS receiver needs two different ground planes. The GND_A pin(11、
12、13、14、15、16、18) shall be connect to analog ground. The GND pin(2、
10、30) connect to digital ground.
(2) Serial Interface:
The Serial interface pin(RXA、TX1、TXB、RXB) is recommended to pull up(10KΩ).
It can increase the stability of serial data.
(3) Backup Battery:
It’s recommended to connect a backup battery to V_BAT.
In order to enable the warm and hot start features of the GPS receiver. If you don’t intend to use a
backup battery, connect this pin to GND or open.
If you use backup battery, shall need to add a bypassing capacitor (10uF) at V_bat trace. It can
reduce noise and increase the stability.
(4) Antenna:
Connecting to the antenna has to be routed on the PCB. The transmission line must to controlled

ET-314
The Specifications are subject to be changed without notice. Copyright ©2007, GlobalSat Technology.
Page 9 of 19
Version 1.2
impedance to connect RF_IN to the antenna or antenna connector of your choice.
(5) Active antenna bias voltage:
The Vcc_RF pin (pin 20) is providing voltage 3.3V. If you use active antenna, you can connect this pin
to V_ANT_IN pin (pin 19) to provide bias voltage of active
GPS Active Antenna Specification(Recommendation)
Frequency: 1575.42+2 MHz
Axial Ratio: 3 dB Typical
output Impedance: 50Ω
Polarization: RHCP
Amplifier Gain :20~26dB Typical
Output VSWR: 2.0 Max.
Noise Figure: 2.0 dB Max
Dimensions

ET-314
The Specifications are subject to be changed without notice. Copyright ©2007, GlobalSat Technology.
Page 10 of 19
Version 1.2
Recommend Layout PAD