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| r4 series gps receiver module data guide
a large-print version of this document is available at www.linxtechnologies.com. warning: 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. warning: linx radio frequency (rf) products may be used to control machinery or devices remotely, including machinery or devices that can cause death, bodily injuries, and/or property damage if improperly or inadvertently triggered, particularly in industrial settings or other applications implicating life-safety concerns. no linx technologies product is intended for use in any application without redundancies where the safety of life or property is at risk. the customers and users of devices and machinery controlled with rf products must understand and must use all appropriate safety procedures in connection with the devices, including without limitation, using appropriate safety procedures to prevent inadvertent triggering by the user of the device and using appropriate security codes to prevent triggering of the remote controlled machine or device by users of other remote controllers. all rf products are susceptible to rf interference that can prevent communication. lack of good sight of the gps satellites (open sky) can affect the accuracy of a position fx or prevent a fx entirely. do not use any linx product over the limits in this data guide. excessive voltage or extended operation at the maximum voltage could cause product failure. exceeding the refow temperature profle could cause product failure which is not immediately evident. do not make any physical or electrical modifcations to any linx product. this will void the warranty and regulatory and ul certifcations and may cause product failure which is not immediately evident. ! table of contents 1 description 1 features 1 applications 2 ordering information 2 electrical specifcations 3 absolute maximum ratings 4 pin assignments 4 pin descriptions 5 a brief overview of gps 5 client generated extended ephemeris (cgee) 6 time to first fix (ttff) 6 module description 7 backup battery 7 power supply requirements 7 the 1pps output 8 antenna considerations 9 power control 10 typical applications 11 slow start time 11 protocols 12 interfacing with nmea messages 13 interfacing with nmea messages 13 cga C global positioning system fixed data 14 gll C geographic position C latitude / longitude 14 gsa C gnss dop and active settings 15 gsv C gnss satellites in view 16 rmc C recommended minimum specifc gnss data 17 vtg C course over ground and ground speed 18 nmea input messages 19 100 C setserialport 20 101 C navigationinitialization 21 103 C query / rate control 23 104 C llanavigationinitialization 24 105 C development data on / off 25 master development system 26 board layout guidelines 27 pad layout 28 microstrip details 29 production guidelines 29 hand assembly 30 automated assembly 31 resources C C 1 description the r4 series gps receiver module is a self-contained high-performance gps receiver. based on the sirfstar iv chipset, it provides exceptional sensitivity, even in dense foliage and urban canyons. the modules very low power consumption helps maximize runtimes in battery powered applications. with over 200,000 effective correlators, the r4 series receiver can acquire and track up to 48 satellites simultaneously in just seconds, even at the lowest signal levels. housed in a compact refow-compatible smd package, the receiver requires no programming or additional rf components (except an antenna) to form a complete gps solution. the modules standard nmea data output makes the r4 series easy to integrate, even by engineers without previous rf or gps experience. features ? sirf star iv chipset ? built-in jammer remover ? high sensitivity (C160dbm) ? 48 channels ? fast ttff at low signal levels ? battery-backed sram ? cgee allows 3-day prediction ? no programming necessary ? no external rf components needed (except an antenna) ? no production tuning ? direct serial interface ? power down feature ? compact surface-mount package ? manual or refow compatible applications include ? positioning and navigation ? location and tracking ? security/loss-prevention ? surveying ? logistics ? fleet management r4 series gps receiver data guide figure 1: package dimensions revised 2/21/2013 gps module rxm-gps-r4 lot grxxxx 0.591 (15.00) 0.512 (13.00) 0.087 (2.20) C C 2 electrical specifcations ordering information ordering information part number description rxm-gps-r4-x r4 series gps receiver module mdev-gps-r4 r4 series gps receiver master development system evm-gps-r4 r4 series gps receiver evaluation module figure 2: ordering information x = t for tape and reel, b for bulk reels are 1,000 pieces quantities less than 1,000 pieces are supplied in bulk r4 series gps receiver specifcations parameter symbol min. typ. max. units notes power supply operating voltage v cc 3.0 3.3 3.6 vdc supply current l cc peak 122 ma 1 acquisition 56 ma 1 tracking 33 ma 1 hibernate 0.43 ma 1 backup battery voltage v bat 2.0 6.0 vdc backup battery current i bat 660 830 a 2 vout output voltage v out vcc 3 output low voltage v ol 0.4 vdc output high voltage v oh tx pin 0.7*vcc vcc vcc vdc 1.8v level pin 1.2 1.8 1.85 vdc output low current i ol 2.0 ma output high current i oh tx pin 0.05 ma 1.8v level pin 2.0 ma input low voltage v il C0.4 0.45 vdc input high voltage v ih 1.3 3.6 vdc lna section input power p in 18 db electrical specifcations C C 3 figure 3: electrical specifcations absolute maximum ratings supply voltage v cc +4.3 vdc input battery backup voltage +7.0 vdc operating temperature ?40 to +85 oc storage temperature ?40 to +85 oc soldering temperature +225c for 10 seconds 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. absolute maximum ratings figure 4: absolute maximum ratings receiver section receiver sensitivity tracking C160 dbm navigation C157 dbm cold start C145 dbm acquisition time hot start (open sky) 1 s hot start (indoor) 15 s cold start 32 s cold start, cgee 15 s position accuracy autonomous 2.5 m sbas 2.5 m altitude 18,000 m velocity 515 m/s chipset sirf star iv, gsd4e rom frequency l1 1575.42mhz, c/a code channels 48 update rate 1hz protocol support nmea 0183 ver 3.0, sirf binary antenna port rf impedance r in 50 1. vcc = 3.3v, without active antenna 2. vcc = 0v 3. vout current is directly sourced from vcc. C C 4 nc 1 nc 2 1pps 3 tx 4 rx 5 gnd 21 nc 6 1pps 7 /reset 8 rfpwrup 9 on_off 10 gnd 20 rfin 19 gnd 18 vout 17 nc 16 gnd 22 nc 15 nc 14 nc 13 vcc 12 vbackup 11 figure 5: r4 series gps receiver pinout (top view) figure 6: r4 series gps receiver pin descriptions pin assignments pin descriptions pin descriptions pin number name i/o description 1, 2, 6, 13, 14, 15, 16, 17 nc ? no electrical connection. 3, 7 1pps o 1 pulse per second. 1.8v level. 4 tx o serial output (default nmea) 5 rx i serial input (default nmea) 8 /reset i reset input, active low. the module has an internal power-on reset circuit so this pin can be left foating 9 rfpwrup o power state indicator 10 on_off i power control pin. if this pin is not used, leave it foating. 11 vbackup p backup battery supply voltage. this line must be powered to enable the module. 12 vcc p supply voltage 18, 20, 21, 22 gnd p ground 17 vout o vcc voltage to supply an active antenna. 19 rfin i gps rf signal input C C 5 a brief overview of gps 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 satellites health, and the almanac data which tells where each satellite should be at any time throughout the day. a gps receiver 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 (fx) 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 fx. 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 frst position fx after power-up. client generated extended ephemeris (cgee) cgee is a type of assisted gps (agps) where the receiver uses the ephemeris data broadcast by the satellites to calculate models of each visible satellites future location. this allows the receiver to store up to 3 days worth of ephemeris data and results in faster ttff. C C 6 time to first fix (ttff) 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 receivers 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. warm or normal: a typical warm start is when the receiver has valid almanac and time data and has not signifcantly 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 second to acquire its position. the time to calculate a fx in this state is sometimes referred to as time to subsequent fix or ttsf. module description the r4 series gps receiver module is based on the sirfstariv chipset, which consumes less power than competitive products while providing exceptional performance even in dense foliage and urban canyons. no external rf components are needed other than an antenna. the simple serial interface and industry standard nmea protocol make integration of the r4 series receiver into an end product extremely straightforward. the modules high-performance rf architecture allows it to receive gps signals that are as low as C160dbm. the r4 series can track up to 48 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. C C 7 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 660a. this means that a small lithium battery is suffcient to power these sections. this signifcantly reduces the power consumption and extends the main battery life while allowing for fast position fxes when the module is powered back on. the backup battery must be installed for cgee start. if the serial command is used to place the receiver into hibernate while keeping vcc powered, then the battery backup current is 15a while the current through the vcc line is about 170a. 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 signifcantly affect the receivers 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 fve or more satellites. the pulse has a duration of 200ms with the rising edge on 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. C C 8 antenna considerations the r4 series module is designed to utilize a wide variety of external antennas. the module has a regulated power output which simplifes the use of gps antenna styles which require external power. this allows the designer great fexibility, 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 fxed and predictable manner may beneft 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 amplifer (lna) after the antenna and before the module to amplify the weak gps satellite signals. for active antennas, a 300 ohm ferrite bead can be used to connect the vout line to the rfin line. this bead prevents the rf from getting into the power supply, but allows 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 modules internal lna. the vout line is connected to the vcc line, so the voltage is the module supply voltage and the current sourcing depends on the modules power supply. maintaining a 50 ohm path between the module and antenna is critical. errors in layout can signifcantly impact the modules performance. please review the layout guidelines elsewhere in this guide carefully to become more familiar with these considerations. C C 9 power control the r4 series gps receiver module offers two power control modes: full power and hibernate. in full power mode the module is fully active and and continuously tracking. measurements are of the highest quality and are continuously output by the module. this is the highest current consumption state. hibernate mode is the lowest power setting. the tracking and processor blocks are powered down, but the rtc is still running and the memory blocks are still powered enabling a hot start. the module switches between these states by toggling the on_off line. the on_off line must go high for at least 100ms to trigger the change of state and must remain low for at least 100ms to reset the edge detector. if the module is in full power mode, a pulse on the on_off line will initiate an orderly shutdown into hibernate mode. if the module is in hibernate mode, a pulse on the on_off line will transistion the module into full power mode. on_off full powe rh ibernate full powe r module power 100ms 100ms figure 7: r4 series gps receiver power control C C 10 nc 1 nc 2 1pps 3 tx 4 rx 5 gnd 21 nc 6 1pps 7 /reset 8 rfpwrup 9 on_off 10 gnd 20 rfin 19 gnd 18 vout 17 nc 16 gnd 22 nc 15 nc 14 nc 13 vcc 12 vbackup 11 p tx rx gnd vcc gnd gnd vcc gnd vcc gnd 300 ferrite bead optional out in nc 1 nc 2 1pps 3 tx 4 rx 5 gnd 21 nc 6 1pps 7 /reset 8 rfpwrup 9 on_off 10 gnd 20 rfin 19 gnd 18 vout 17 nc 16 gnd 22 nc 15 nc 14 nc 13 vcc 12 vbackup 11 p tx rx gnd vcc gnd gnd vcc gnd vcc gnd optional out in typical applications figure 8: circuit using the r4 series module with a passive antenna figure 9: circuit using the r4 series module with a an active antenna C C 11 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 fx or if the location has signifcantly 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 fx and the more accurate the position will be when the fx 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 frst fx 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 fnd a location with a better view of the sky and fewer obstructions. once locked, it is easier for the receiver to maintain the position fx. protocols linx gps modules use the sirfstar iv 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, its recommended that sirf binary use 115,200bps. for a detailed description of the sirf binary protocol, see the sirf binary protocol reference manual, available from sirf technology, inc. note: although sirf binary protocol may be used with the module, linx only offers tech support for the nmea protocol. C C 12 interfacing with nmea messages linx modules default to the nmea protocol. output messages are sent from the receiver on the tx pin and input messages are sent to the receiver on the rx 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: C C 13 interfacing with nmea 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 C global positioning system fixed data figure 10 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 global positioning system fixed data example name example units description message id $gpgga gga protocol header utc time 053740.000 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 figure 11 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 felds when dgps is not used diff. ref. station 0000 checksum *64 C C 14 gll C geographic position C latitude / longitude figure 12 below contains the values for the following example: $gpgll,2503.6319,n,12136.0099,e,053740.000,a,a*52 gsa C gnss dop and active satellites figure 13 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 gnss dop and active satellites example name example units description message id $gpgsa gsa protocol header mode 1 a see figure 14 mode 2 3 1=no fx, 2=2d, 3=3d id of satellite used 24 sv on channel 1 id of satellite used 07 sv on channel 2 ... ... id of satellite used sv on channel 12 pdop 2.0 position dilution of precision hdop 1.1 horizontal dilution of precision vdop 1.7 vertical dilution of precision checksum *35 C C 15 gsv C gnss satellites in view figure 15 below contains the values for the following example: $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 $gpgsv,3,3,12,08,22,214,38,27,08,190,16,19,05,092,33,23,04,127,*7b mode 1 values value description m manual C forced to operate in 2d or 3d mode a automatic C allowed to automatically switch 2d/3d figure 15: gnss satellites in view example gnss satellites in view example name example units description message id $gpgsv gsv protocol header total number of messages 1 3 range 1 to 3 message number 1 1 range 1 to 3 satellites in view 12 satellite id 28 channel 1 (range 01 to 196) elevation 81 degrees channel 1 (range 00 to 90) azimuth 285 degrees channel 1 (range 000 to 359) snr (c/no) 42 db-hz channel 1 (range 00 to 99, null when not tracking) satellite id 20 channel 4 (range 01 to 32) elevation 51 degrees channel 4 (range 00 to 90) azimuth 077 degrees channel 4 (range 00 to 359) snr (c/no) 46 db-hz channel 4 (range 00 to 99, null when not tracking. checksum *73 C C 16 rmc C recommended minimum specifc gnss data figure 16 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 recommended minimum specifc gnss data example name example units description message id $gprmc rmc protocol header utc time 053740.000 hhmmss.sss status a a=data valid or v=data not valid 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 speed over ground 2.69 knots true course over ground 79.65 degrees date 100106 ddmmyy magnetic variation degrees not available, null feld variation sense e=east or w=west (not shown) mode a a=autonomous, d=dgps, n= data not valid checksum *53 C C 17 vtg C course over ground and ground speed figure 17 below contains the values for the following example: $gpvtg,79.65,t,,m,2.69,n,5.0,k,a*38 course over ground and ground speed example name example units description message id $gpvtg vtg protocol header course over ground 79.65 degrees measured heading reference t true course over ground degrees measured heading (n/a, null feld) reference m magnetic speed over ground 2.69 knots measured speed units n knots speed over ground 5.0 km/hr measured speed units k kilometer per hour mode a a=autonomous, d=dgps, n= data not valid checksum *38 C C 18 nmea input messages the following outlines the serial commands input into the module for confguration. by default, the commands are input at 9,600bps, 8 data bits, no parity and 2 stop bits. all felds in all proprietary nmea messages are required; none are optional. all nmea messages are comma delimited. figure 19 below outlines the message identifers supported by the module. serial data structure name example description start sequence $psrf message id C C 19 100 C setserialport 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. figure 20 below contains the values for the following example: switch to sirf binary protocol at 9600,8,n,1 $psrf100,0,9600,8,1,0*0c for details on the sirf binary protocol, please refer to sirfs binary protocol reference manual. setserialport example name example description message id $psrf100 psrf100 protocol header protocol 0 0=sirf binary, 1=nmea baud 9600 4800, 9600, 19200, 38400, 57600, 115200 databits 8 8 1 stopbits 1 0, 1 1 parity 0 0=none, 1=odd, 2=even 1 checksum *0c C C 20 101 C navigationinitialization this command is used to initialize the receiver with the current position (in x, y, z coordinates), clock offset, and time, enabling a faster fx. 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 felds are no longer supported. figure 21 below contains the values for the following example: $psrf101,-2686700,-4304200,3851624,96000,497260,921,12,3*1c figure 21: navigationinitialization example navigationinitialization example name example units description message id $psrf101 psrf101 protocol header ecef x -2686700 meters x coordinate position ecef y -4304200 meters y coordinate position ecef z 3851624 meters z coordinate position clkoffset 96000 hz clock offset 1 timeofweek 497260 seconds gps time of week weekno 921 gps week number channelcount 12 range 1 to 12 resetcfg 3 see figure 22 checksum *1f C C 21 103 C query / rate control 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. figure 23 below contains the values for the following example: 1. query the gga message with checksum enabled $psrf103,00,01,00,01*25 2. enable vtg message for a 1hz constant output with checksum enabled $psrf103,05,00,01,01*20 3. disable vtg message $psrf103,05,00,00,01*21 query / rate control example 1 name example units description message id $psrf103 psrf103 protocol header msg 00 see figure 24 mode 01 0=setrate, 1=query rate 00 seconds output: off=0, max=255 cksumenable 01 0=disable, 1=enable checksum checksum *25 C C 22 msgvalues value description 0 gga 1 gll 2 gsa 3 gsv 4 rmc 5 vtg 6 mss (not supported) 7 not defned 8 zda 9 not defned figure 24: msg values C C 23 104 C llanavigationinitialization this command is used to initialize the receiver with the current position (in lattitude, longitude and altitude coordinates), clock offset, and time, enabling a faster fx. 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 felds are no longer supported. figure 25 below contains the values for the following example: $psrf104,37.3875111,-121.97232,0,96000,237759,1946,12,1*07 figure 25: navigationinitialization example llanavigationinitialization example name example units description message id $psrf104 psrf104 protocol header latitude 37.3875111 degrees latitude position (range 90 to C90) longitude C121.97232 degrees longitude position (range 180 to C180) altitude 0 meters altitude position clkoffset 96000 hz clock offset of the evaluation receiver1 timeofweek 237759 seconds gps time of week weekno 1946 extended gps week number (1024 added) channelcount 12 range 1 to 12 resetcfg 1 see figure 26 checksum *07 C C 24 105 C development data on / off use this command to enable development data information if you are having trouble getting commands accepted. invalid commands generate debug information that helps to determine the source of the command rejection. common reasons for input command rejection are invalid checksum or parameter out of specifed range. figure 27 below contains the values for the following example: 1. debug on $psrf105,1*3e 2. debug off $psrf105,0*3f 117 C system turn off this message requests that the gps receiver perform an orderly shutdown and switch to hibernate mode. figure 28 below contains the values for the following example: $psrf117,16*0b figure 27: development data on / off example development data on / off example 1 name example units description message id $psrf105 psrf105 protocol header debug 1 0=off, 1=on checksum *3e C C 25 master development system the r4 series master development system provides all of the tools necessary to evaluate the r4 series gps receiver module. the system includes a fully assembled development board, an active antenna, development software and full documentation. the development board includes a power supply, a prototyping area for custom circuit development, and an oled display that shows the gps data without the need for a computer. a usb interface is also included for use with a pc running custom software or the included development software. the master development system software enables confguration of the receiver and displays the satellite data output by the receiver. the software can select from among all of the supported nmea protocols for display of the data. full documentation for the board and software is included in the development system, making integration of the module straightforward. figure 29: the r4 series master development system figure 30: the r4 series master development system software C C 26 board layout guidelines the modules design makes integration straightforward; however, it is still critical to exercise care in pcb layout. failure to observe good layout techniques can result in a signifcant degradation of the modules performance. a primary layout goal is to maintain a characteristic 50-ohm impedance throughout the path from the antenna to the module. grounding, fltering, decoupling, routing and pcb stack-up are also important considerations for any rf design. the following section provides some basic design guidelines which may be helpful. during prototyping, the module should be soldered to a properly laid-out circuit board. the use of prototyping or perf boards will result in poor performance and is strongly discouraged. the module should, as much as reasonably possible, be isolated from other components on your pcb, especially high-frequency circuitry such as crystal oscillators, switching power supplies, and high-speed bus lines. when possible, separate rf and digital circuits into different pcb regions. make sure internal wiring is routed away from the module and antenna, and is secured to prevent displacement. do not route pcb traces directly under the module. there should not be any copper or traces under the module on the same layer as the module, just bare pcb. the underside of the module has traces and vias that could short or couple to traces on the products circuit board. the pad layout section shows a typical pcb footprint for the module. a ground plane (as large and uninterrupted as possible) should be placed on a lower layer of your pc board opposite the module. this plane is essential for creating a low impedance return for ground and consistent stripline performance. use care in routing the rf trace between the module and the antenna or connector. keep the trace as short as possible. do not pass under the module or any other component. do not route the antenna trace on multiple pcb layers as vias will add inductance. vias are acceptable for tying together ground layers and component grounds and should be used in multiples. C C 27 each of the modules ground pins should have short traces tying immediately to the ground plane through a via. bypass caps should be low esr ceramic types and located directly adjacent to the pin they are serving. a 50-ohm coax should be used for connection to an external antenna. a 50-ohm transmission line, such as a microstrip, stripline or coplanar waveguide should be used for routing rf on the pcb. the microstrip details section provides additional information. in some instances, a designer may wish to encapsulate or pot the product. there is a wide variety of potting compounds with varying dielectric properties. since such compounds can considerably impact rf performance and the ability to rework or service the product, it is the responsibility of the designer to evaluate and qualify the impact and suitability of such materials. pad layout the pad layout diagram in figure 31 is designed to facilitate both hand and automated assembly. 0.028 (0.70) 0.036 (0.92) 0.512 (13.00) 0.050 (1.27) 0.050 (1.27) 0.036 (0.92) 0.020 (0.50) 0.045 (1.15) figure 31: recommended pcb layout C C 28 microstrip details a transmission line is a medium whereby rf energy is transferred from one place to another with minimal loss. this is a critical factor, especially in high-frequency products like linx rf modules, because the trace leading to the modules antenna can effectively contribute to the length of the antenna, changing its resonant bandwidth. in order to minimize loss and detuning, some form of transmission line between the antenna and the module should be used, unless the antenna can be placed very close (< 1 ? 8 in) to the module. one common form of transmission line is a coax cable; another is the microstrip. this term refers to a pcb trace running over a ground plane that is designed to serve as a transmission line between the module and the antenna. the width is based on the desired characteristic impedance of the line, the thickness of the pcb, and the dielectric constant of the board material. for standard 0.062" thick fr-4 board material, the trace width would be 111 mils. the correct trace width can be calculated for other widths and materials using the information below. handy software for calculating microstrip lines is also available on the linx website, www.linxtechnologies.com. trace board ground plane example microstrip calculations dielectric constant width/height ratio (w/d) effective dielectric constant characteristic impedance ( ) 4.80 1.8 3.59 50.0 4.00 2.0 3.07 51.0 2.55 3.0 2.12 48.0 figure 32: microstrip formulas figure 33: example microstrip calculations C C 29 production guidelines the modules are housed in a hybrid smd package that supports hand and automated assembly techniques. since the modules contain discrete components internally, the assembly procedures are critical to ensuring the reliable function of the modules. the following procedures should be reviewed with and practiced by all assembly personnel. hand assembly pads located on the bottom of the module are the primary mounting surface. since these pads are inaccessible during mounting, castellations that run up the side of the module have been provided to facilitate solder wicking to the modules underside. this allows for very quick hand soldering for prototyping and small volume production. if the recommended pad guidelines have been followed, the pads will protrude slightly past the edge of the module. use a fne soldering tip to heat the board pad and the castellation, then introduce solder to the pad at the modules edge. the solder will wick underneath the module, providing reliable attachment. tack one module corner frst and then work around the device, taking care not to exceed the times listed below. castellations pcb pads soldering iron tip solder warning: pay attention to the absolute maximum solder times. absolute maximum solder times hand solder temperature tx: +225oc for 10 seconds hand solder temperature rx: +225oc for 10 seconds recommended solder melting point: +180oc refow oven: +240c max. (see figure 36) ! C C 30 automated assembly for high-volume assembly, most users will want to auto-place the modules. the modules have been designed to maintain compatibility with refow processing techniques; however, due to their hybrid nature, certain aspects of the assembly process are far more critical than for other component types. following are brief discussions of the three primary areas where caution must be observed. refow temperature profle the single most critical stage in the automated assembly process is the refow stage. the refow profle below should not be exceeded, since excessive temperatures or transport times during refow will irreparably damage the modules. assembly personnel will need to pay careful attention to the ovens profle to ensure that it meets the requirements necessary to successfully refow all components while still remaining within the limits mandated by the modules. figure 36 shows the recommended refow oven profle for the modules. shock during refow transport since some internal module components may refow along with the components placed on the board being assembled, it is imperative that the modules not be subjected to shock or vibration during the time solder is liquid. should a shock be applied, some internal components could be lifted from their pads, causing the module to not function properly. 125c 185c 217c 255c 235c 60 120 30 1501 80 2102 40 2703 00 3303 60 09 0 50 100 150 200 250 300 recommended rohs profil e max rohs profil e recommended non-rohs profil e 180c temperature ( o c) time (seconds) figure 36: maximum re ow pro le C C 31 washability the modules are wash resistant, but are not hermetically sealed. linx recommends wash-free manufacturing; however, the modules can be subjected to a wash cycle provided that a drying time is allowed prior to applying electrical power to the modules. the drying time should be suffcient to allow any moisture that may have migrated into the module to evaporate, thus eliminating the potential for shorting damage during power-up or testing. if the wash contains contaminants, the performance may be adversely affected, even after drying. resources support for technical support, product documentation, application notes, regulatory guidelines and software updates, visit www.linxtechnologies.com rf design services for customers who need help implementing linx modules, linx offers design services including board layout assistance, programming, certifcation advice and packaging design. for more complex rf solutions, apex wireless, a division of linx technologies, creates optimized designs with rf components and frmware selected for the customers application. call +1 800 736 6677 (+1 541 471 6256 if outside the united states) for more information. antenna factor antennas linxs antenna factor division has the industrys broadest selection of antennas for a wide variety of applications. for customers with specialized needs, custom antennas and design services are available along with simulations of antenna performance to speed development. learn more at www.linxtechnologies.com. by linx technologies 159 ort lane merlin, or, us 97532 3090 sterling circle suite 200 boulder, co 80301 phone: +1 541 471 6256 fax: +1 541 471 6251 www.linxtechnologies.com disclaimer l inx technologies is continually striving to improve the quality and function of its products. for this reason, we reserve the right to make changes to our products without notice. the information contained in this data guide is believed to be accurate as of the time of publication. specifcations are based on representative lot samples. values may vary from lot-to-lot and are not guaranteed. typical parameters can and do vary over lots and application. linx technologies makes no guarantee, warranty, or representation regarding the suitability of any product for use in any specifc application. it is the customers responsibility to verify the suitability of the part for the intended application. no linx product is intended for use in any application where the safety of life or property is at risk. linx technologies disclaims all warranties of merchantability and fitness for a particular purpose. in no event shall linx technologies be liable for any of customers incidental or consequential damages arising in any way from any defective or non-conforming products or for any other breach of contract by linx technologies. the limitations on linx technologies liability are applicable to any and all claims or theories of recovery asserted by customer, including, without limitation, breach of contract, breach of warranty, strict liability, or negligence. customer assumes all liability (including, without limitation, liability for injury to person or property, economic loss, or business interruption) for all claims, including claims from third parties, arising from the use of the products. the customer will indemnify, defend, protect, and hold harmless linx technologies and its offcers, employees, subsidiaries, affliates, distributors, and representatives from and against all claims, damages, actions, suits, proceedings, demands, assessments, adjustments, costs, and expenses incurred by linx technologies as a result of or arising from any products sold by linx technologies to customer. under no conditions will linx technologies be responsible for losses arising from the use or failure of the device in any application, other than the repair, replacement, or refund limited to the original product purchase price. devices described in this publication may contain proprietary, patented, or copyrighted techniques, components, or materials. under no circumstances shall any user be conveyed any license or right to the use or ownership of such items. all rights reserved. ?2013 linx technologies the stylized linx logo, wireless made simple, cipherlinx and the stylized cl logo are trademarks of linx technologies. mouser electronics authorized distributor click to view pricing, inventory, delivery & lifecycle information: linx technologies: ? 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