RXM-GPS-SG-B

RXM-GPS-SG WIRELESS MADE SIMPLE ® SG SERIES GPS RECEIVER MODULE DATA GUIDE DESCRIPTION 0.591 The SG Series GPS receiver module is a self(15.00) contained high-performance GPS receiver with an on-board LNA and SAW filter. Based on the SiRFstar III chipset, it provides exceptional sensitivity, even in dense foliage and urban canyons. The module’s very 0.512 GPS MODULE (13.00) low power consumption helps maximize runtimes in RXM-GPS-SG battery powered applications. With over 200,000 effective correlators, the SG Series receiver can LOT GRxxxx acquire and track up to 20 satellites simultaneously in 0.087 just seconds, even at the lowest signal levels. (2.20) Housed in a compact reflow-compatible SMD package, the receiver requires no programming or Figure 1: Package Dimensions additional RF components (except an antenna) to form a complete GPS solution. Five GPIOs are easily configured through simple serial commands. These features, along with the module’s standard NMEA data output, make the SG Series easy to integrate, even by engineers without previous RF or GPS experience. FEATURES n n n n n n n n n SiRF Star III chipset 200,000+ correlators Low power consumption (46mW) High sensitivity (-159dBm) 20 channels Fast TTFF at low signal levels Battery-backed SRAM 5 User Definable GPIOs No programming necessary APPLICATIONS INCLUDE n n n n n n Positioning and Navigation Location and Tracking Security/Loss-Prevention Surveying Logistics Fleet Management n No external RF components needed (except an antenna) n No production tuning n Direct serial interface n Power down feature n Compact surface-mount package n Manual or reflow compatible n RoHS compliant ORDERING INFORMATION PART # DESCRIPTION RXM-GPS-SG-x GPS Receiver Module MDEV-GPS-SG Master Development System x = “T” for Tape and Reel, “B” for Bulk Reels are 1,000 pcs. Quantities less than 1,000 pcs. are supplied in bulk Revised 1/10/11 ELECTRICAL SPECIFICATIONS Parameter Notes: Designation Min. Typical Max. Units Notes POWER SUPPLY Supply Voltage VCC 3.0 – 4.2 VDC 1 Supply Current: ICC – 32 28 1.5 – 46.0 – – – 6.0 mA mA mA mA VDC 6 6 6 6 – 2 Peak Acquisition Tracking Standby Backup Battery Voltage VBAT – – – – 1.3 Backup Battery Current IBAT – 10 – µA – 2.85V Output Voltage VOUT 2.79 2.85 2.91 VDC – 2.85V Output Current IOUT – – 30 mA 3 Output Logic Low Voltage VOL – – 0.25*VOUT VDC – Output Logic High Voltage VOH 0.75*VOUT – – VDC – Output Logic Low Current IOL – 2 – mA – Output Logic High Current IOH – 2 – mA – Input Logic Low Voltage VIL -0.3 – 0.3*VOUT VDC – Input Logic High Voltage VIH 0.7*VOUT – 3.6 VDC – Input Logic Low Current IIL -60 – 20 µA – With Pull-down Input Logic High Current IIH – -60 – – 60 20 µA µA – – With Pull-down Input Capacitance CIN – – – – 60 4 µA pF – – Output Capacitance COUT – – 4 pF 4 LNA SECTION Insertion Power Gain |S21|2 – 18 – dB 5 NF – 0.9 – dB 5 RIN – 50 – Ω – Noise Figure ANTENNA PORT RF Input Impedance ENVIRONMENTAL Operating Temperature Range Storage Temperature Range RECEIVER SECTION Receiver Sensitivity Tracking Cold Start Acquisition Time Hot Start (Open Sky) Hot Start (Indoor) Cold Start Position Accuracy Autonomous SBAS Altitude Velocity Chipset Firmware Version Frequency Channels Update Rate Protocol Support – -30 – +85 -40 25 +85 °C °C – – – – -159 -144 – – dBm dBm – – – – – – – 35 2 15 – S S S – – – 10 5 60,000 1,000 m m ft Knots – – – – – – – – – – – – SiRF Star III, GSC3f/LPx 7990 GSW3.5.0_3.5.00.00-SDK-3EP2.01A L1 1575.42MHz, C/A Code 20 1Hz NMEA 0183 ver 3.0, SiRF Binary 1. 2. 3. 4. 5. 6. IOUT = 0 VCC = 3.3V, IOUT = 0 VCC = 3.3V Output buffer At 25°C With passive antenna. Active antennas will increase current consumption. ABSOLUTE MAXIMUM RATINGS Supply Voltage VCC Input Battery Backup Voltage 2.85V Output Current Operating Temperature Storage Temperature Soldering Temperature +6.5 +7.0 50 -30 to +85 -40 to +125 +225°C for 10 seconds VDC VDC mA °C °C *NOTE* Exceeding any of the limits of this section may lead to permanent damage to the device. Furthermore, extended operation at these maximum ratings may reduce the life of this device. *CAUTION* This product incorporates numerous static-sensitive components. Always wear an ESD wrist strap and observe proper ESD handling procedures when working with this device. Failure to observe this precaution may result in module damage or failure. ONLINE RESOURCES ® – www.linxtechnologies.com • • • • • Latest News Data Guides Application Notes Knowledgebase Software Updates If you have questions regarding this or any Linx product make www.linxtechnologies.com your first stop. Day or night, the Linx website gives you instant access to the latest information regarding the products and services of Linx. It’s all here: manual and software updates, application notes, a comprehensive knowledgebase, FCC information, and much more. Here you will find the answers you need arranges in an intuitive format. Be sure to visit often! Table 1: SG Series Receiver Specifications Page 2 Page 3 PIN ASSIGNMENTS A BRIEF OVERVIEW OF GPS 1 2 3 4 5 21 6 7 8 9 10 NC NC 1PPS TXA RXA GND GPIO10 LCKIND GPIO1 RFPWRUP ON_OFF GND RFIN GND VOUT NC GND GPIO13 GPIO15 GPIO14 VCC VBACKUP 20 19 18 17 16 22 15 14 13 12 11 Figure 2: SG Series Receiver Pinout (Top View) PIN DESCRIPTIONS Pin # Name I/O Description 1, 2, 16 NC – No Connect. No electrical connection. 3 1PPS O Pulse per second (1uS pulse) 4 TXA O Serial output for channel A (default NMEA) 5 RXA I Serial input for channel A (default NMEA) 6 GPIO10 I/O General Purpose I/O 7 LCKIND O Lock Indicator 8 GPIO1 I/O General Purpose I/O, 100kΩ pull down 9 RFPWRUP O Indicate power state 10 ON_OFF I Edge triggered soft on/off request. Should only be used to wake up the module when the RFPWRUP line is low. 11 VBACKUP P Backup battery supply voltage. This line must be powered to enable the module. 12 VCC P Supply Voltage 13 GPIO14 I/O General Purpose I/O, 100kΩ pull up 14 GPIO15 I/O General Purpose I/O, 100kΩ pull up 15 GPIO13 I/O General Purpose I/O 17 VOUT P 2.85V Linear regulator power output 18,20-22 GND P Ground 19 RFIN I GPS RF signal input Page 4 The Global Positioning System (GPS) is a U.S.-owned utility that freely and continuously provides positioning, navigation, and timing (PNT) information. Originally created by the U.S. Department of Defense for military applications, the system was made available without charge to civilians in the early 1980s. The global positioning system consists of a nominal constellation of 24 satellites orbiting the earth at about 12,000 nautical miles in height. The pattern and spacing of the satellites allow at least four to be visible above the horizon from any point on the Earth. Each satellite transmits low power radio signals which contain three different bits of information; a pseudorandom code identifying the satellite, ephemeris data which contains the current date and time as well as the satellite’s health, and the almanac data which tells where each satellite should be at any time throughout the day. A GPS receiver such as the Linx SG Series GPS module receives and times the signals sent by multiple satellites and calculates the distance to each satellite. If the position of each satellite is known, the receiver can use triangulation to determine its position anywhere on the earth. The receiver uses four satellites to solve for four unknowns; latitude, longitude, altitude, and time. If any of these factors is already known to the system, an accurate position (Fix) can be obtained with fewer satellites in view. Tracking more satellites improves calculation accuracy. In essence, the GPS system provides a unique address for every square meter on the planet. A faster Time To First Fix (TTFF) is also possible if the satellite information is already stored in the receiver. If the receiver knows some of this information, then it can accurately predict its position before acquiring an updated position fix. For example, aircraft or marine navigation equipment may have other means of determining altitude, so the GPS receiver would only have to lock on to three satellites and calculate three equations to provide the first position fix after power-up. TTFF is often broken down into three parts: Cold: A cold start is when the receiver has no accurate knowledge of its position or time. This happens when the receiver’s internal Real Time Clock (RTC) has not been running or it has no valid ephemeris or almanac data. In a cold start, the receiver takes 35 to 40 seconds to acquire its position. If new almanac data is required, this may take up to 15 minutes (see page 9 for more details). Warm or Normal: A typical warm start is when the receiver has valid almanac and time data and has not significantly moved since its last valid position calculation. This happens when the receiver has been shut down for more than 2 hours, but still has its last position, time, and almanac saved in memory, and its RTC has been running. The receiver can predict the location of the current visible satellites and its location; however, it needs to wait for an ephemeris broadcast (every 30 seconds) before it can accurately calculate its position. Hot or Standby: A hot start is when the receiver has valid ephemeris, time, and almanac data. This happens when the receiver has been shut down for less than 2 hours and has the necessary data stored in memory with the RTC running. In a hot start, the receiver takes 1 to 2 seconds to acquire its position. The time to calculate a fix in this state is sometimes referred to as Time to Subsequent Fix or TTSF. Page 5 MODULE DESCRIPTION By default, the SG Series will operate in full power mode. However, it also has a built-in power control mode called Adaptive Trickle Power mode. The module is based on the SiRFstar III low power chipset, which consumes significantly less power than competitive products while providing exceptional performance even in dense foliage and urban canyons. The module includes an internal SAW filter and LNA, so no external RF components are needed other than an antenna. The simple serial interface and industry standard NMEA protocol make integration of the SG Series receiver into an end product or system extremely straightforward. The module’s high-performance RF architecture allows it to receive GPS signals that are as low as -159dBm. With over 200,000 effective correlators, the SG Series can track up to 20 satellites at the same time. Once locked onto the visible satellites, the receiver calculates the range to the satellites and determines its position and the precise time. It then outputs the data through a standard serial port using several standard NMEA protocol formats. The GPS core handles all of the necessary initialization, tracking, and calculations autonomously, so no programming is required. The RF section is optimized for low level signals, and requires no production tuning of any type. ANTENNA CONSIDERATIONS The SG Series module is designed to utilize a wide variety of external antennas. The module has a regulated power output which simplifies the use of GPS antenna styles which require external power. This allows the designer great flexibility, but care must be taken in antenna selection to ensure optimum performance. For example, a handheld device may be used in many varying orientations so an antenna element with a wide and uniform pattern may yield better overall performance than an antenna element with high gain and a correspondingly narrower beam. Conversely, an antenna mounted in a fixed and predictable manner may benefit from pattern and gain characteristics suited to that application. Evaluating multiple antenna solutions in real-world situations is a good way to rapidly assess which will best meet the needs of your application. For GPS, the antenna should have good right hand circular polarization characteristics (RHCP) to match the polarization of the GPS signals. Ceramic patches are the most commonly used style of antenna, but there are many different shapes, sizes and styles of antennas available. Regardless of the construction, they will generally be either passive or active types. Passive antennas are simply an antenna tuned to the correct frequency. Active antennas add a Low Noise Amplifier (LNA) after the antenna and before the module to amplify the weak GPS satellite signals. For active antennas, the VOUT line can provide 2.85V at 30mA to power the external LNA. A 300 ohm ferrite bead should be used to connect this line to the RFIN line. This bead will prevent the RF from getting into the power supply, but will allow the DC voltage onto the RF trace to feed into the antenna. A series capacitor inside the module prevents this DC voltage from affecting the bias on the module’s internal LNA. Maintaining a 50 ohm path between the module and antenna is critical. Errors in layout can significantly impact the module’s performance. Please review the layout guidelines elsewhere in this guide carefully to become more familiar with these considerations. Page 6 BACKUP BATTERY The module is designed to work with a backup battery that keeps the SRAM memory and the RTC powered when the RF section and the main GPS core are powered down. This enables the module to have a faster Time To First Fix (TTFF) when the it is powered back on. The memory and clock pull about 10µA. This means that a small lithium battery is sufficient to power these sections. This significantly reduces the power consumption and extends the main battery life while allowing for fast position fixes when the module is powered back on. POWER SUPPLY REQUIREMENTS The module requires a clean, well-regulated power source. While it is preferable to power the unit from a battery, it can operate from a power supply as long as noise is less than 20mV. Power supply noise can significantly affect the receiver’s sensitivity, therefore providing clean power to the module should be a high priority during design. Bypass capacitors should be placed as close as possible to the module. The values should be adjusted depending on the amount and type of noise present on the supply line. THE 1PPS OUTPUT The 1PPS line outputs 1 pulse per second on the rising edge of the GPS second when the receiver has an over-solved navigation solution from five or more satellites. The pulse has a duration of 1µS and an accuracy of about 1µS from the GPS second. This line is low until the receiver acquires an over-solved navigation solution (a lock on more than 4 satellites). The GPS second is based on the atomic clocks in the GPS satellites, which are monitored and set to Universal Time master clocks. This output and the time calculated from the GPS satellite transmissions can be used as a clock feature in an end product. GENERAL PURPOSE I/O The SG Series module has five general purpose I/Os (GPIOs) that are configured using four simple input messages: set the I/Os as inputs or outputs, read the states of the inputs, write the states of the outputs, and read the current configuration and states of all of the GPIOs. This offers the system additional lines without increasing the size or load on the user’s microcontroller. Refer to the NMEA Input Messages section for details on the commands. THE LOCK INDICATOR LINE The Lock Indicator line outputs a series of 100mS pulses with a 50% duty cycle when the module is searching for a fix. Once the receiver acquires a solution, the line outputs a single 100mS pulse every second. This line can be connected to a microcontroller to monitor the state of the module or connected to an LED as a visual indicator. Voltage Voltage 1 0 Seconds Position Fixed 0 1 Searching for Fix Seconds Figure 3: SG Series Lock Indicator Signals Page 7 POWER CONTROL TYPICAL APPLICATIONS The SG Series has a built-in power control mode called Adaptive Trickle Power mode. In this mode, the receiver will power on at full power to acquire and track satellites and obtain satellite data. It then powers off the RF stage and only uses its processor stage (CPU) to determine a position fix (which takes about 160mS). Once the fix is obtained, the receiver goes into a low power standby state. After a user-defined period of time, the receiver wakes up to track the satellites for a user-defined period of time, updates its position using the CPU only, and then resumes standby. The initial acquisition time is variable, depending on whether it is a cold start or assisted, but a maximum acquisition time is definable. This cycling of power is ideal for battery-powered applications since it significantly reduces the amount of power consumed by the receiver while still providing similar performance to the full power mode. In normal conditions, this mode provides a fixed power savings, but under poor signal conditions, the receiver returns to full power to improve performance. The receiver sorts the satellites according to signal strength and if the fourth satellite is below 26dB-Hz, then the receiver switches to full power. Once the fourth satellite is above 30dB-Hz, the receiver returns to Adaptive Trickle Power mode. For optimum performance, SiRF recommends cycle times of 300mS track to 1S interval or 400mS track to 2S interval. CPU time is about 160mS to compute the navigation solution and empty the UART. There are some situations in which the receiver stays in full power mode. These are: to collect periodic ephemeris data, to collect periodic ionospheric data, to perform RTC convergence, and to improve the navigation result. Depending on states of the power management, the receiver will be in one of three system states: All RF and baseband circuitry are fully powered. There is a difference in power consumption during acquisition mode and tracking mode. Acquisition requires more processing, so it consumes more power. This is the initial state of the receiver and it stays in this state until a reliable position solution is achieved. CPU Only State This state is entered when the satellite measurements have been collected but the navigation solution still needs to be computed. The RF and DSP processing are no longer needed and can be turned off. Stand-By State In this state, the RF section is completely powered off and the clock to the baseband is stopped. About 1mA of current is drawn in this state for the internal core regulator, RTC and battery-backed RAM. The receiver enters this state when a position fix has been computed and reported. The table below shows the RFPWRUP and Vout conditions in each power state. RFPWRUP H H L Table 2: RFPWRUP and VOUT conditions Page 8 VCC VCC RX TX µP GND GND 1 2 3 4 5 21 6 7 8 9 10 NC NC 1PPS TXA RXA GND GPIO10 LCKIND GPIO1 RFPWRUP ON_OFF GND RFIN GND VOUT NC GND GPIO13 GPIO15 GPIO14 VCC VBACKUP 20 19 18 17 16 22 15 14 13 12 11 GND VCC GND GND Figure 4: SG Series Module with a Passive Antenna Figure 5 shows a circuit using the GPS module with an active antenna. VCC VCC µP RX TX GND GND 1 2 3 4 5 21 6 7 8 9 10 NC NC 1PPS TXA RXA GND GPIO10 LCKIND GPIO1 RFPWRUP ON_OFF GND RFIN GND VOUT NC GND GPIO13 GPIO15 GPIO14 VCC VBACKUP 20 19 18 17 16 22 15 14 13 12 11 300Ω Ferrite Bead GND VCC GND GND Full Power State Power State Full power CPU only Stand by Figure 4 shows a circuit using the GPS module with a passive antenna. VOUT Enabled Enabled Enabled Figure 5: SG Series Module with an Active Antenna SLOW START TIME The most critical factors in start time are current ephemeris data, signal strength, and sky view. The ephemeris data describes the path of each satellite as they orbit the earth. This is used to calculate the position of a satellite at a particular time. This data is only usable for a short period of time, so if it has been more than a few hours since the last fix or if the location has significantly changed (a few hundred miles), then the receiver may need to wait for a new ephemeris transmission before a position can be calculated. The GPS satellites transmit the ephemeris data every 30 seconds. Transmissions with a low signal strength may not be received correctly or be corrupted by ambient noise. The view of the sky is important because the more satellites the receiver can see, the faster the fix and the more accurate the position will be when the fix is obtained. If the receiver is in a very poor location, such as inside a building, urban canyon, or dense foliage, then the time to first fix can be slowed. In very poor locations with poor signal strength and a limited view of the sky with outdated ephemeris data, this could be on the order of several minutes. In the worst cases, the receiver may need to receive almanac data, which describes the health and course data for every satellite in the constellation. This data is transmitted every 15 minutes. If a lock is taking a long time, try to find a location with a better view of the sky and fewer obstructions. Once locked, it is easier for the receiver to maintain the position fix. Page 9 PROTOCOLS LINX GPS modules use the SiRFstar III chipset. This chipset allows two protocols to be used, NMEA-0183 and SiRF Binary. Switching between the two is handled using a single serial command. The NMEA protocol uses ASCII characters for the input and output messages and provides the most common features of GPS development in a small command set. The SiRF Binary protocol uses BYTE data types and allows more detailed control over the GPS receiver and its functionality using a much larger command set. Although both protocols have selectable baud rates, it’s recommended that SiRF Binary use baud rates of 38,400bps or higher. For a detailed description of the SiRF Binary protocol, see the SiRF Binary Protocol Reference Manual, available from SiRF Technology, Inc. Although SiRF Binary protocol may be used with the module, Linx only offers tech support for the NMEA protocol. INTERFACING WITH NMEA MESSAGES Linx modules default to the NMEA protocol. Output messages are sent from the receiver on the TXA pin and input messages are sent to the receiver on the RXA pin. By default, output messages are sent once every second. Details of each message are described in the following sections. The NMEA message format is as follows: . The serial data structure defaults to 9,600bps, 8 data bits, 1 stop bit, and no parity bits. Each message starts with a $ character and ends with a . All fields within each message are separated by a comma. The checksum follows the * character and is the last two characters, not including the . It consists of two hex digits representing the exclusive OR (XOR) of all characters between, but not including, the $ and * characters. When reading NMEA output messages, if a field has no value assigned to it, the comma will still be placed following the previous comma. For example, {,04,,,,,2.0,} shows four empty fields between values 04 and 2.0. When writing NMEA input messages, all fields are required, none are optional. An empty field will invalidate the message and it will be ignored. Reading NMEA output messages: • Initialize a serial interface to match the serial data structure of the GPS receiver. • Read the NMEA data from the TXA pin into a receive buffer. • Separate it into six buffers, one for each message type. Use the characters ($) and as end points for each message. NMEA OUTPUT MESSAGES The following sections outline the data structures of the various NMEA protocols that are supported by the module. By default, the NMEA commands are output at 9,600bps, 8 data bits, no parity, and 1 stop bit. GGA – Global Positioning System Fixed Data The table below contains the values for the following example: $GPGGA,053740.000,2503.6319,N,12136.0099,E,1,08,1.1,63.8,M,15.2,M,,0000*64 Name Example Units Description Message ID $GPGGA GGA protocol header UTC Time 053740 hhmmss.sss Latitude 2503.6319 ddmm.mmmm N/S indicator N N=north or S=south Longitude 12136.0099 dddmm.mmmm E/W Indicator E E=east or W=west Position Fix Indicator 1 See Table 4 Satellites Used 08 Range 0 to 12 HDOP 1.1 Horizontal Dilution of Precision MSL Altitude 63.8 meters Units M meters Geoid Separation 15.2 meters Units M meters Age of Diff. Corr. second Null fields when DGPS is not used Diff. Ref. Station ID 0000 Checksum *64 End of message termination Table 3: Global Positioning System Fixed Data Example Value Description • For each message, calculate the checksum as mentioned above to compare with the checksum received. 0 Fix not available or invalid • Parse the data from each message using commas as field separators. 1 GPS SPS Mode, fix valid • Update the application with the parsed field values. 2 Differential GPS, SPS Mode, fix valid (Not Supported) • Clear the receive buffer and be ready for the next set of NMEA messages. Writing NMEA input messages: • Initialize a serial interface to match the serial data structure of the GPS receiver. 3-5 6 Not supported Dead Reckoning Mode, fix valid Table 4: Position Indicator Values • Assemble the message to be sent with the calculated checksum. • Transmit the message to the receiver on the RXA pin. Page 10 Page 11 GLL – Geographic Position – Latitude / Longitude GSV – GNSS Satellites in View The table below contains the values for the following example: The table below contains the values for the following example: $GPGLL,2503.6319,N,12136.0099,E,053740.000,A,A*52 Name Example Units $GPGSV,3,1,12,28,81,285,42,24,67,302,46,31,54,354,,20,51,077,46*73 $GPGSV,3,2,12,17,41,328,45,07,32,315,45,04,31,250,40,11,25,046,41*75 Description Message ID $GPGLL GLL protocol header Latitude 2503.6319 ddmm.mmmm N/S indicator N Longitude $GPGSV,3,3,12,08,22,214,38,27,08,190,16,19,05,092,33,23,04,127,*7B Name Example N=north or S=south Message ID $GPGSV GSV protocol header 12136.0099 dddmm.mmmm 3 Range 1 to 3 E/W indicator E E=east or W=west Total number of messages1 UTC Time 053740 hhmmss.sss Message number1 1 Range 1 to 3 Status A A=data valid or V=data not valid Mode A A=autonomous, D=DGPS Checksum *52 End of message termination Table 5: Geographic Position – Latitude / Longitude Example GSA – GNSS DOP and Active Satellites The table below contains the values for the following example: $GPGSA,A,3,24,07,17,11,28,08,20,04,,,,,2.0,1.1,1.7*35 Name Example Units Units Description Satellites in view 12 Satellite ID 28 Channel 1 (Range 01 to 32) Elevation 81 degrees Channel 1 (Range 00 to 90) Azimuth 285 degrees Channel 1 (Range 000 to 359) SNR (C/No) 42 dB-Hz Satellite ID 20 Channel 4 (Range 01 to 32) Elevation 51 degrees Channel 4 (Range 00 to 90) Azimuth 77 degrees Channel 4 (Range 000 to 359) SNR (C/No) 46 dB-Hz *73 Description Message ID $GPGSA GSA protocol header Mode1 A See Table 7 Checksum Channel 1 (Range 00 to 99, null when not tracking) Channel 4 (Range 00 to 99, null when not tracking) End of message termination Mode 2 3 1=No Fix, 2=2D, 3=3D ID of satellite used 24 Sv on Channel 1 Table 8: GNSS Satellites in View Example ID of satellite used 7 Sv on Channel 2 1. Depending on the number of satellites tracked, multiple messages of GSV data may be required. ... ... ID of satellite used Sv on Channel 12 PDOP 2 Position Dilution of Precision HDOP 1.1 Horizontal Dilution of Precision VDOP 1.7 Vertical Dilution of Precision Checksum *35 End of message termination Table 6: GNSS DOP and Active Satellites Example Value Description M Manual - forced to operate in 2D or 3D mode A Automatic - allowed to automatically switch 2D/3D Table 7: Mode1 Values Page 12 Page 13 NMEA INPUT MESSAGES RMC – Recommended Minimum Specific GNSS Data The table below contains the values for the following example: $GPRMC,053740.000,A,2503.6319,N,12136.0099,E,2.69,79.65,100106,,,A*53 Name Example Units Description Message ID $GPRMC RMC protocol header UTC Time 53740 hhmmss.sss Status A A=data valid or V=data not valid Latitude 2503.632 ddmm.mmmm N/S Indicator N N=north or S=south Longitude 12136.01 dddmm.mmmm E/W Indicator E E=east or W=west Speed over ground 2.69 Course over ground 79.65 Date knots Name Message ID Message Identifier consisting of three numeric characters. Input messages begin at MID 100. Payload DATA Message specific data. CKSUM CKSUM is a two-hex character checksum as defined in the NMEA specification, NMEA-0183 Standard For Interfacing Marine Electronic Devices. Checksums are required on all input messages. Each message must be terminated using Carriage Return (CR) Line Feed (LF) (\r\n, 0x0D0A) to cause the receiver to process the input message. They are not printable ASCII characters, so are omitted from the examples. ddmmyy degrees Variation Sense Not Available, Null Field End Sequence E=east or W=west (Not shown) Mode A A=autonomous, D=DGPS, E=DR Checksum *53 End of message termination Table 11: Serial Data Structure All fields in all proprietary NMEA messages are required; none are optional. All NMEA messages are comma delimited. The table below outlines the message identifiers supported by the module. Table 9: Recommended Minimum Specific GNSS Data Example VTG – Course Over Ground and Ground Speed Message The table below contains the values for the following example: Example Message ID $GPVTG Course over ground 79.65 Reference T Course over ground Set PORT A parameters and protocol NavigationInitialization 101 Reset the modules VTG protocol header Query/Rate Control 103 Query standard NMEA message and/or set output rate Measured heading LLANavigationInitialization 104 Reset the modules Development Data On/Off 105 Development Data messages On/Off PowerManagement 200 Sets the power performance of the receiver StaticNavigation 202 Sets static navigation On/Off SetIO 211 Sets the I/O lines to an input or output ReadInput 212 Reads the state of the inputs lines WriteOutput 213 Writes the state of an output line Query 215 Get configuration and current state of all GPIOs Description TRUE degrees Measured heading (N/A, Null Field) Reference M Speed over ground 2.69 Units N Speed over ground 5 Units K Kilometer per hour Mode A A=autonomous, E=DR Checksum *38 Magnetic knots Measured speed Knots km/hr Description 100 Units degrees MID SetSerialPort $GPVTG,79.65,T,,M,2.69,N,5.0,K,A*38 Name Description Start Sequence $PSRF Checksum TRUE Example degrees 100106 Magnetic Variation The following outlines the serial commands input into the module for configuration. By default, the commands are input at 9,600bps, 8 data bits, no parity, and 1 stop bit. Measured speed Table 12: Message ID Values End of message termination Table 10: Course Over Ground and Ground Speed Example Page 14 Page 15 100 – SetSerialPort 101 – NavigationInitialization This command message is used to set the protocol (SiRF binary or NMEA) and/or the communication parameters (baud rate). Generally, this command is used to switch the module back to SiRF binary protocol mode where a more extensive command message set is available. When a valid message is received, the parameters are stored in battery-backed SRAM and the receiver restarts using the saved parameters. This command was used to initialize the receiver with the current position (in X, Y, Z coordinates), clock offset, and time, enabling a faster fix. Increased receiver sensitivity and the removal of Selective Availability (SA) have made this unneccessary. The command is retained for its ability to reset the module, but the initialization fields are no longer supported. The table below contains the values for the following example: The table below contains the values for the following example: $PSRF101,0,0,0,96000,0,0,12,4*1F Switch to SiRF binary protocol at 9600,8,N,1 $PSRF100,0,9600,8,1,0*0C Name Example Description Name Example Message ID $PSRF101 Message ID $PSRF100 PSRF100 protocol header ECEF X 0 Protocol 0 0=SiRF binary, 1=NMEA ECEF Y 0 Baud 9600 4800, 9600, 19200, 38400, 57600 ECEF Z 0 DataBits 8 81 ClkOffset 96000 StopBits 1 11 TimeOfWeek 0 Parity 0 0=None1 WeekNo 0 Checksum *0C Units Description PSRF101 protocol header ChannelCount 12 End of message termination Table 13: SetSerialPort Example 2 1. SiRF protocol is only valid for 8 data bits, 1 stop bit, and no parity. 2. Default settings are NMEA protocol using 9,600 baud, 8 data bits, 1 stop bit, and no parity. ResetCfg 4 Checksum *1F See Table 15 End of message termination Table 14: NavigationInitialization Example For details on the SiRF binary protocol, please refer to SiRF’s Binary Protocol Reference Manual. Hex Description 0x01 Hot Start – All data valid 0x02 Warm Start – Ephemeris cleared 0x04 Cold Start – Clears all data in memory 0x08 Clear Memory – Clears all data in memory and resets the receiver back to factory defaults Table 15: ResetCfg Values Page 16 Page 17 103 – Query/Rate Control 104 – LLANavigationInitialization This command is used to control the output of standard NMEA messages GGA, GLL, GSA, GSV, RMC, and VTG. Using this command message, standard NMEA messages may be polled once, or setup for periodic output. Checksums may also be enabled or disabled depending on the needs of the receiving program. NMEA message settings are saved in battery-backed memory for each entry when the message is accepted. This command was used to initialize the receiver with the current position (in lattitude, longitude and altitude coordinates), clock offset, and time, enabling a faster fix. Increased receiver sensitivity and the removal of Selective Availability (SA) have made this unneccessary. The command is retained for its ability to reset the module, but the initialization fields are no longer supported. The table below contains the values for the following example: The table below contains the values for the following example: 1. Query the GGA message with checksum enabled $PSRF104,0,0,0,96000,0,0,12,4*1A $PSRF103,00,01,00,01*25 2. Enable VTG message for a 1 Hz constant output with checksum enabled $PSRF103,05,00,01,01*20 3. Disable VTG message $PSRF103,05,00,00,01*21 Name Example Units Description Name Example Message ID $PSRF104 Latitude 0 Longitude 0 Message ID $PSRF103 PSRF103 protocol header Altitude 0 Msg 0 See Table 17 ClkOffset 96000 Mode 1 0=SetRate, 1=Query TimeOfWeek 0 Rate 0 Output – off=0, max=255 WeekNo 0 CksumEnable 1 0=Disable, 1=Enable Checksum ChannelCount 12 Checksum *25 ResetCfg 4 Checksum *1A seconds End of message termination Table 16: Query/Rate Control Example 1 Value Description 0 GGA 1 GLL 2 GSA 3 GSV 4 Units Description PSRF104 protocol header See Table 19 End of message termination Table 18: LLANavigationInitialization Example Hex Description 0x01 Hot Start – All data valid 0x02 Warm Start – Ephemeris cleared RMC 0x04 Cold Start – Clears all data in memory 5 VTG 0x08 Clear Memory – Clears all data in memory and resets receiver back to factory defaults 6 MSS (Not Supported) 7 Not defined 8 ZDA 9 Not defined Table 19: ResetCfg Values Table 17: MSG Values 1. Default setting is GGA, GLL, GSA, GSV, RMC, and VTG NMEA messages are enabled with checksum at a rate of 1 second. Page 18 Page 19 105 – Development Data On/Off 200 – PowerManagement Use this command to enable development data information if you are having trouble getting commands accepted. Invalid commands generate debug information that enables you to determine the source of the command rejection. Common reasons for input command rejection are invalid checksum or parameter out of specified range. The table below contains the values for the following example to set the receiver to Adaptive Trickle Power mode: $PLSC,200,2,300,1000,300000,30000*0E Name The table below contains the values for the following example: MID 1. Debug On Mode Units $PLSC,200 OnTime 300 (200 - 900) See Table 22 mS Must be > 200mS and a multiple of 100 (if not, it is rounded up to the nearest multiple of 100). mS Must be an integer value > 1000 and