ET-332

Version 1.3.1

1. Product Information

Product Part I.D. ET-332

Product Description:

The ET-332 GPS engine board is low cost but maintains high reliability and accuracy making it an

ideal choice for integration with OEM/ODM systems.

Product Features:

9 SiRF Star III/ LP Single

9 Very high sensitivity (Tracking Sensitivity: -159dBm)

9 Compact PCB allows for easier integration into space limited environments.

9 Supports the NMEA 0183 data protocol

9 Foliage Lock for weak signal tracking

9 All-in-view 20-channel parallel processing

9 Snap Lock 100mc re-acquisition time

9 Enhanced algorithm for navigation stability

9 Superior urban canyon performance

9 WAAS / EGNOS MSAS support

9 Built-in SuperCap to maintain system data for rapid satellite acquisition

9 RoHS compliant

Product Specifications

GPS Receiver

Chipset

SiRF Star III/LP Single

Frequency

L1, 1575.42 MHz

Code

1.023 Mhz chip rate

Protocol

Electrical Level: TTL level,

Output Voltage Level: 0V~2.85V

Baud Rate: 4800 bps

Output Message: NMEA 0183 GGA, GSA,

GSV, RMC (VTG, GLL optional)

Channels

Sensitivity

-159dBm

Cold Start

42 seconds average

Specifications are subject to be changed without notice.

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ET-332

Version 1.3.1

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 (60,000 feet) max

Maximum Velocity

515 meter/second (1000 knots) max

Maximum Acceleration

Jerk

20m/sec **3

Interface

I/O Connector Type

External Antenna Port

Physical Characteristics

Dimensions

1.6” x 1.4” x 0.4” (40.5 x 35 x 10 mm)

DC Characteristics

Power Supply

3.8V ~ 6.5V DC Input

Backup Voltage

2.5 ~ 3.6V 10uA backup current

Power Consumption

42mA (Continuous Mode)

25mA (Trickle Power Mode)

Environmental Range

Humidity Range

5% to 95% non-condensing

Operation Temperature

-40F to +176F (-40C to +85C)

Specifications are subject to be changed without notice.

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ET-332

Version 1.3.1

Pin Assignment

Name

Description

Type

GND

Ground

VBAT

Backup Battery

Input

VDC

3.8V~6.5V DC Power Input

Input

PBRES

Push Button Reset Input (Active Low)

Input

GPIO1

(Reserved)

TXA

Serial Data Output A (GPS Data)

Output

RXA

Serial Data Input A (Command)

Input

GND

Ground

GND

Ground

SELECT

(Reserved)

TIMEMARK

1PPS Time Mark Output

Output

GND

Ground

Specifications are subject to be changed without notice.

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ET-332

Version 1.3.1

Pin Explanation

VCC: (DC power input) This is the main DC supply for a 3.8V ~ 6.5V power module board.

VBAT: This is the battery backup input that powers the SRAM and RTC when main power is removed.

Typical current draw is 10uA. 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. To maximize battery lifetime, the battery voltage should be between 2.5v and

3.6v.

PBRES: (Push Button Reset) This pin provides an active-low reset input to the engine board. It causes

the engine board to reset and start searching for satellites.

SELECT: Do not connect (do not use)

TX: This is the main transmit channel for outputting navigation and measurement data to user’s

navigation software or user-written software. Output TTL level, 0V ~ 2.85V

RX: This is the main receive channel for receiving software commands to the engine board from

SiRfdemo software or from user-written software. (NOTE: When not in use this pin must be kept “HIGH”

for operation. From Vcc connect a 470 Ohm resistor in series with a 3.2v Zener diode to Ground. Then,

connect the Rx input to Zener’s cathode to pull the input “HIGH”.)

TIME MARK (1PPS): This pin provides one pulse-per-second output from the engine board that is

synchronized to GPS time

GND: GND provides the ground for the engine boards. Be sure to connect all grounds

Mounting

Recommended mounting methods:

a. Use industrial grade double-sided foam tape. Place it on the bottom side of the engine board.

A recessed cavity in your housing design with a foam pad to eliminate shifting or movement.

Use provided mounting holes on the GPS engine board PCB.

3. Software Commands

NMEA Output Command

GGA-Global Positioning System Fixed Data

Table B-2 contains the values for the following example:

$GPGGA,161229.487,3723.2475,N,12158.3416,W,1,07,1.0,9.0,M,,,,0000*18

Specifications are subject to be changed without notice.

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ET-332

Version 1.3.1

Table B-2 GGA Data Format

Name

Example

Units

Description

Message ID

$GPGGA

GGA protocol header

UTC Time

161229.487

hhmmss.sss

Latitude

3723.2475

ddmm.mmmm

N/S Indicator

N=north or S=south

Longitude

12158.3416

dddmm.mmmm

E/W Indicator

E=east or W=west

Position Fix Indicator

See Table B-3

Satellites Used

Range 0 to 12

HDOP

1.0

Horizontal Dilution of Precision

MSL Altitude¹

9.0

meters

Units

meters

Geoid Separation¹

meters

Units

meters

Age of Diff. Corr.

second

Null fields when DGPS is not used

Diff. Ref. Station ID

0000

Checksum

*18

End of message termination

SiRF Technology Inc. does not support geoid corrections. Values are WGS84 ellipsoid heights.

Table B-3 Position Fix Indicator

Value

Description

Fix not available or invalid

GPS SPS Mode, fix valid

Differential GPS, SPS Mode , fix valid

GPS PPS Mode, fix valid

GLL-Geographic Position-Latitude/Longitude

Table B-4 contains the values for the following example:

$GPGLL,3723.2475,N,12158.3416,W,161229.487,A*2C

Table B-4 GLL Data Format

Name

Example

Units

Description

Message ID

$GPGLL

GLL protocol header

Latitude

3723.2475

ddmm.mmmm

N/S Indicator

N=north or S=south

Longitude

12158.3416

dddmm.mmmm

E/W Indicator

E=east or W=west

Specifications are subject to be changed without notice.

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ET-332

Version 1.3.1

UTC Position

161229.487

hhmmss.sss

Status

A=data valid or V=data not valid

Checksum

*2C

End of message termination

GSA-GNSS DOP and Active Satellites

Table B-5 contains the values for the following example:

$GPGSA,A,3,07,02,26,27,09,04,15,,,,,,1.8,1.0,1.5*33

Table B-5 GSA Data Format

Name

Example

Units

Description

Message ID

$GPGSA

GSA protocol header

Mode1

See Table B-6

Mode2

See Table B-7

Satellite Used¹

Sv on Channel 1

Satellite Used¹

Sv on Channel 2

Satellite Used¹

Sv on Channel 12

PDOP

1.8

Position dilution of Precision

HDOP

1.0

Horizontal dilution of Precision

VDOP

1.5

Vertical dilution of Precision

Checksum

*33

End of message termination

1. Satellite used in solution.

Table B-6 Mode1

Value

Description

Manual-forced to operate in 2D or 3D mode

2D automatic-allowed to automatically switch 2D/3D

Table B-7 Mode 2

Value

Description

Fix Not Available

GSV-GNSS Satellites in View

Table B-8 contains the values for the following example:

$GPGSV,2,1,07,07,79,048,42,02,51,062,43,26,36,256,42,27,27,138,42*71

Specifications are subject to be changed without notice.

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ET-332

Version 1.3.1

$GPGSV,2,2,07,09,23,313,42,04,19,159,41,15,12,041,42*41

Table B-8 GSV Data Format

Name

Example

Units

Description

Message ID

$GPGSV

GSV protocol header

Number of Messages¹

Range 1 to 3

Message Number¹

Range 1 to 3

Satellites in View

Satellite ID

Channel 1(Range 1 to 32)

Elevation

degrees

Channel 1(Maximum90)

Azimuth

048

degrees

Channel 1(True, Range 0 to 35

SNR(C/No)

dBHz

Range 0 to 99,null when not tra

…….

Satellite ID

Channel 4 (Range 1 to 32)

Elevation

Degrees

Channel 4(Maximum90)

Azimuth

138

Degrees

Channel 4(True, Range 0 to 35

SNR(C/No)

dBHz

Range 0 to 99,null when not tra

Checksum

*71

End of message termination

Depending on the number of satellites tracked multiple messages of GSV data may be required.

Specifications are subject to be changed without notice.

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ET-332

Version 1.3.1

RMC-Recommended Minimum Specific GNSS Data

Table B-9 contains the values for the following example:

$GPRMC,161229.487,A,3723.2475,N,12158.3416,W,0.13,309.62,120598,,*10

Table B-9 RMC Data Format

Name

Example

Units

Description

Message ID

$GPRMC

RMC protocol header

UTC Time

161229.487

hhmmss.sss

Status

A=data valid or V=data not valid

Latitude

3723.2475

ddmm.mmmm

N/S Indicator

N=north or S=south

Longitude

12158.3416

dddmm.mmmm

E/W Indicator

E=east or W=west

Speed Over Ground

0.13

knots

Course Over Ground

309.62

degrees

True

Date

120598

ddmmyy

Magnetic Variation²

degrees

E=east or W=west

Checksum

*10

End of message termination

SiRF Technology Inc. does not support magnetic declination. All “course over ground” data are

Geodetic WGS48 directions.

VTG-Course Over Ground and Ground Speed

$GPVTG,309.62,T,,M,0.13,N,0.2,K*6E

Table B-9 VTG Data Format

Name

Example

Units

Description

Message ID

$GPVTG

VTG protocol header

Course

309.62

degrees

Measured heading

Reference

True

Course

degrees

Measured heading

Reference

Magnetic

Speed

0.13

knots

Measured horizontal speed

Units

Knots

Speed

0.2

Km/hr

Measured horizontal speed

Units

Kilometers per hour

Checksum

*6E

End of message termination

Specifications are subject to be changed without notice.

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ET-332

Version 1.3.1

̰ NMEA Input Command

A.) Set Serial Port ID:100 Set PORTA parameters and protocol

This command message is used to set the protocol (SiRF Binary, NMEA, or USER1) and/or the

communication parameters (baud, data bits, stop bits, parity). Generally, this command is utilize to

switch the GPS module back to SiRF Binary protocol mode, where an extensive message

commands are readily available. In example, whenever users are interested in altering navigation

parameters, a valid message sent and is receive by the recipient module, the new parameters will be

stored in battery backed SRAM and then the receiver will restart using the saved parameters.

Format:

$PSRF100,<protocol>,<baud>,<DataBits>,<StopBits>,<Parity>*CKSUM

0=SiRF Binary, 1=NMEA, 4=USER1

<baud>

1200, 2400, 4800, 9600, 19200, 38400

8,7. Note that SiRF protocol is only valid f8 Data bits

0,1

0=None, 1=Odd, 2=Even

Example 1: Switch to SiRF Binary protocol at 9600,8,N,1

$PSRF100,0,9600,8,1,0*0C<CR><LF>

Example 2: Switch to User1 protocol at 38400,8,N,1

$PSRF100,4,38400,8,1,0*38<CR><LF>

**Checksum Field: The absolute value calculated by exclusive-OR the 8 data bits of each

character in the Sentence, between, but, excluding “$” and “*”. The hexadecimal value of the most

significant and least significant 4 bits of the result are converted to two ASCII characters (0-9,A-F)

for transmission. First, the most significant character is transmitted.

**<CR><LF>

: Hex 0D 0A

B.) Navigation initialization ID:101 Parameters required for start

This command is used to initialize the GPS module for a “Warm” start, by providing real-time position

ഔin X, Y, Z coordinates), clock offset, and time. This action enables the GPS receiver to search for

the necessary satellite signals at the correct signal parameters. The newly acquired and stored

satellite data will enable the receiver to acquire signals more quickly, and thus, generate a rapid

navigational solution.

When a valid Navigation Initialization command is receive, the receiver will restart using the input

parameters as a basis for satellite selection and acquisition.

Format

$PSRF101,<X>,<Y>,<Z>,<ClkOffset>,<TimeOfWeek>,<WeekNo>,<chnlCount>,<ResetCfg>

*CKSUM<CR><LF>

<X>

X coordinate position

INT32

Specifications are subject to be changed without notice.

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ET-332

Version 1.3.1

<Y>

Y coordinate position

INT32

<Z>

Z coordinate position

INT32

Clock offset of the receiver in Hz, Use 0 for last saved value if available.

If this is unavailable, a default value of 75000 for GSP1, 95000 for GSP

1/LX is used.

INT32

GPS Time Of Week

UINT32

GPS Week Number

UINT16

Week No and Time Of Week calculation from UTC time

Number of channels to use.1-12. If your CPU throughput is not high

enough, you could decrease needed throughput by reducing the number

of active channels

UBYTE

bit mask

0×01=Data Valid warm/hotstarts=1

0×02=clear ephemeris warm start=1

0×04=clear memory. Cold start=1

UBYTE

Example: Start using known position and time.

$PSRF101,-2686700,-4304200,3851624,96000,497260,921,12,3*7F

C.) Set DGPS Port ID:102 Set PORT B parameters for DGPS input

This command is used to control Serial Port B, an input serial only port used to receive RTCM

differential corrections. Differential receivers may output corrections using different communication

parameters. The default communication parameters for PORT B are set for 9600 Baud, 8data bits, 0

stop bits, and no parity. If a DGPS receiver is used which has different communication parameters,

use this command to allow the receiver decode data correctly. When a valid message is received,

the parameters are stored in a battery backed SRAM. Resulting, GPS receiver using the saved

Parameters for restart.

Format:

$PSRF102,<Baud>,<DataBits>,<StopBits>,<Parity>*CKSUM<CR><LF>

<baud>

1200,2400,4800,9600,19200,38400

0,1

0=None,Odd=1,Even=2

Example: Set DGPS Port to be 9600,8,N,1

$PSRF102,9600,8,1.0*12

D.) Query/Rate Control ID:103 Query standard NMEA message and/or set output rate

Specifications are subject to be changed without notice.

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ET-332

Version 1.3.1

This command is used to control standard NMEA data output messages: GGA, GLL, GSA, GSV,

RMC, and VTG. Using this command message, standard NMEA message is polled once, or setup

for periodic output. In addition, checksums may also be enable or disable contingent on receiving

program requirements. NMEA message settings are stored in a battery-backed memory for each

entry when the message is accepted.

Format:

$PSRF103,<msg>,<mode>,<rate>,<cksumEnable>*CKSUM<CR><LF>

<msg>

0=GGA,1=GLL,2=GSA,3=GSV,4=RMC,5=VTG

<mode>

0=SetRate,1=Query

<rate>

Output every <rate>seconds, off=0,max=255

0=disable Checksum,1=Enable checksum for specified message

Example 1: Query the GGA message with checksum enabled

$PSRF103,00,01,00,01*25

Example 2: Enable VTG message for a 1Hz constant output with checksum enabled

$PSRF103,05,00,01,01*20

Example 3: Disable VTG message

$PSRF103,05,00,00,01*21

E.) LLA Navigation initialization ID:104 Parameters required to start using Lat/Lon/Alt

This command is used to initialize the GPS module for a “Warm” start, providing real-time position

(Latitude, Longitude, Altitude coordinates), clock offset, and time. This action enables the GPS

receiver to search for the necessary satellite signals at the correct signal parameters. The newly

acquired and stored satellite data will enable the receiver to acquire signals more quickly, and thus,

generate a rapid navigational solution.

When a valid LLA Navigation Initialization command is receive, then the receiver will restart using

the input parameters as a basis for satellite selection and acquisition.

Format:

$PSRF104,<Lat>,<Lon>,<Alt>,<ClkOffset>,<TimeOfWeek>,<WeekNo>,

<ChannelCount>, <ResetCfg>*CKSUM<CR><LF>

<Lat>

Latitude position, assumed positive north of equator and negative

south of equator float, possibly signed

<Lon>

Longitude position, it is assumed positive east of Greenwich

and negative west of Greenwich Float, possibly signed

<Alt>

Altitude position float, possibly signed

Clock Offset of the receiver in Hz, use 0 for last saved value if

available.

Specifications are subject to be changed without notice.

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Version 1.3.1

If this is unavailable, a default value of 75000 for GSP1, 95000 for

GSP1/LX is used.

INT32

GPS Time Of Week

UINT32

GPS Week Number

UINT16

Number of channels to use. 1-12

UBYTE

bit mask

0×01=Data Valid warm/hot starts=1

0×02=clear ephemeris warm start=1

0×04=clear memory. Cold start=1

UBYTE

Example: Start using known position and time.

$PSRF104,37.3875111,-121.97232,0,96000,237759,922,12,3*37

F.) Development Data On/Off ID:105 Switch Development Data Messages On/Off

Use this command to enable development debug information if you are having trouble in attaining

commands accepted. Invalid commands will generate debug information that should enable the

user to determine the source of the command rejection. Common input rejection problems are

associated to invalid checksum or parameter out of specified range. Note, this setting is not

preserved across a module reset.

Format:

$PSRF105,<debug>*CKSUM<CR><LF>

<debug>

0=Off,1=On

Example: Debug On

$PSRF105,1*3E

Example: Debug Off

$PSRF105,0*3F

G). Select Datum ID:106 Selection of datum to be used for coordinate transformations

GPS receivers perform initial position and velocity calculations using an earth-centered earth-fixed

(ECEF) coordinate system. Results may be converted to an earth model (geoid) defined by the

selected datum. The default datum is WGS 84 (World Geodetic System 1984) which provides a

worldwide common grid system that may be translated into local coordinate systems or map Datum.

(Local map Datum are a best fit to the local shape of the earth and not valid worldwide.)

Examples:

Datum select TOKYO_MEAN

$PSRF106,178*32

Specifications are subject to be changed without notice.

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