u-blox LEA-4R, System Integration Manual And Reference Design

Page 1: ...ules It guides through a design and provides information to get maximum GPS performance at very low power consumption u blox AG Zürcherstrasse 68 8800 Thalwil Switzerland www u blox com Phone 41 1722 7444 Fax 41 1722 7447 info u blox com LEA 4R TIM 4R System Integration Manual Reference Design Manual This docu de fe an ...

Page 2: ...lox harmless from any consequences u blox reserves the right to make changes to this product including its circuits and software in order to improve its design and or performance without prior notice u blox makes no warranties neither expressed nor implied regarding the information and specifications contained in this document u blox assumes no responsibility for any claims or damages arising from...

Page 3: ...ces by email Use our service pool email addresses rather than any personal email address of our staff This makes sure that your request is processed as soon as possible You will find the contact details at the end of the document By Phone If an email contact is not the right choice to solve your problem or does not clearly answer your questions call the nearest Technical Support office for assista...

Page 4: ...perature Sensor 12 2 3 Pinout tables 13 2 4 Layout Design In Checklist for ANTARIS 4 14 2 5 Layout 14 3 Receiver Description 15 3 1 Dead Reckoning enabled GPS module DR module 15 3 1 1 Architecture 15 3 1 2 Input Signals Sensors 17 3 1 3 DR specific Parameters 20 3 1 4 DR Calibration 21 3 1 5 Storage of Parameters 23 3 1 6 Static Position 24 3 2 Power Saving Modes 24 3 3 Antenna and Antenna Superv...

Page 5: ...est 33 5 3 1 Guidelines for Sensitivity Tests 33 5 3 2 Go No go tests for integrated devices 33 5 4 Testing of LEA 4R TIM 4R Designs 34 5 4 1 Direction Signal 34 5 4 2 Speedpulse Signal 34 5 4 3 Gyroscope Rate Input 34 5 4 4 Temperature Sensor 34 5 4 5 Erase Calibration 34 6 PC Support Tools 35 A Migration from TIM LR to TIM 4R 36 A 1 Migration from TIM LR to TIM 4R pin out 37 B Default Settings 3...

Page 6: ...tion is our focus C Reference Design for TIM 4R 42 D Mechanical Data 43 D 1 Dimensions 43 D 2 Specification 44 Glossary 45 LEA 4R TIM 4R System Integration Manual Reference Design Content GPS G4 MS4 05043 Page 6 ...

Page 7: ...ion Time Calibration Turn Rate Speed Forward Backward GPS Signals GPS Position GPS Data Figure 1 Dead Reckoning Block diagram 1 2 Dead Reckoning Principle In contrast to GPS which delivers absolute positions Dead Reckoning is a relative method The sensors give information for a defined measurement period and the location is calculated relative to the previously known position Therefore an absolute...

Page 8: ...d Φ Actual route Length S x y Figure 3 Dead Reckoning Performance Parameters The seamless transition between absolute GPS positions and relative DR positions is advantageous in getting optimal performance from a DR enabled GPS receiver ANTARIS 4 GPS Technology employs blended algorithms to obtain the optimum from both systems GPS Positioning is weighted more heavily as long as the GPS parameter e ...

Page 9: ...TARIS 4 DR Technology performs a calculation by blending the GPS and sensor based positioning Good GPS With good GPS performance and optimal sky view the GPS position has a higher weight than the DR sensor based position on the overall navigation solution In this situation the GPS position values are used to calibrate the DR sensors or to perform sensor integrity checks to establish if the sensors...

Page 10: ...ttery is a must for DR enabled GPS receiver s designs Make sure to connect a backup battery to V_BAT LEA 4R TIM 4R do not operate without a backup battery When you connect the backup battery for the first time make sure VCC is on or if not possible power up the module for a short time e g 1s ASAP in order to avoid excessive battery drain While power off make sure there are no pull up or down resis...

Page 11: ...T 1 8V if not used You need to check the voltage levels and the quality of the vehicle signals They may be of different voltage levels for example 12V nominal with a certain degree of variation Use of optocouplers or other approved EMI protection and filtering is strongly recommended 2 2 2 Odometer Speedpulses DR receivers use signals from sensors in the car to establish the velocity and distance ...

Page 12: ...O Input Serial data Master In Slave Out 28 MOSI Output Serial data Master Out Slave In leave open Table 2 SPI Pin for TIM 4R The following block schematic specifies the A D converter and temperature sensor for the LEA 4R and TIM 4R Please note that the National LM70 3 sensor functions at 3V If the 5V version LM70 5 is used a level translation with open drain buffers and pull up resistors at the ou...

Page 13: ...ND I Ground 12 BOOT_INT I Boot mode GND I Ground 13 GND I Ground GND I Ground 14 GND I Ground GND I Ground 15 GND I Ground GND I Ground 16 RF_IN I GPS signal input GND I Ground 17 GND I Ground RF_IN I GPS signal input 18 VCC_RF O Output Voltage RF sect GND I Ground 19 V_ANT I Antenna Bias voltage V_ANT I Antenna Bias voltage 20 AADET_N I Active Antenna Detect VCC_RF O Output Voltage RF section 21 ...

Page 14: ...Calculation of the micro strip The micro strip must be 50 Ohms and it must be routed in a section of the PCB where minimal interference from noise sources can be expected In case of a multi layer PCB use the thickness of the dielectric between the signal and the 1st GND layer typically the 2nd layer for the micro strip calculation If the distance between the micro strip and the adjacent GND area o...

Page 15: ...ration Manual 5 In order to store any DR specific data such as last position current heading calibration data the temperature compensation table TC etc a DR module requires a backup battery Furthermore these data are stored in Flash in repetitive intervals Note Do not use any power saving modes e g FixNow Mode as the DR algorithm and power saving modes are incompatible 3 1 1 1 Enhanced Kalman Filt...

Page 16: ...o be checked for mechanical failures all calibration parameter Sensor Calibration and Temperature Calibration have to be reset and an initial calibration see Section3 1 4 has to be done For short minimal errors the system is able to recover itself In this case the error will be cleared and the DR module will report combined position solutions again Note The INF message ERROR EKF disabled Gyro data...

Page 17: ...ity Gyro Bias as function of the temperature Any differences from the Gyro Bias Offset over the entire temperature range are stored in a lookup table called Temperature Compensation Table TC This table covers a temperature range of 40 deg Celsius to 80 deg Celsius Turn Rate w deg s 100 Gyro Voltage 0 100 2 5 5 0 0 Gyro Bias Offset typical Gyro Sensitivity Gyro Scale Factor real Gyro Sensitivity Fi...

Page 18: ...om 40 to 85 degrees Celsius The table is continuously updated with new values as soon as the receiver is stationary no odometer pulses at the input for more than 3 seconds This process allows the receiver to learn about the temperature characteristics of the individual gyro in its specific environment The TC stabilizes as more measurements are observed for the same temperature For temperature rang...

Page 19: ...ut it can be configured vice versa in UBX CFG Config EKF EKF Settings It s recommended to use a direction indicator for best DR performance If no direction signal is available it s recommended to set the direction to forward Consequences if no direction signal is available Direction GPS coverage Forward Backward Insufficient to determine a position DR only The direction signal indicates the right ...

Page 20: ...s 0 High Forward The axis or the direction of rotation of the Gyro if the voltage output is positive can be set default setting is 0 Clockwise Rotation The hardware can also be configured to simplify calibration This does not however eliminate the need to perform a calibration The Odometer can be configured to set the number of speedpulses per kilometer default value is 3500 pulses km The nominal ...

Page 21: ...ion Gyroscope Bias Voltage level of the gyroscope while driving a straight route or not moving Gyroscope Scale Factor Adjusts of left and right turns gyro sensitivity Speed Pulse Scale Factor Used to calibrate odometer pulse frequency to GPS speed over ground Temperature Compensation The gyroscope is a temperature dependent device that requires temperature compensation When a new GPS receiver is i...

Page 22: ...he mentioned distances and durations are typical values a better indication are the quality indicators of the calibration values in UBX NAV Navigation EKF Status Status The Percentage values indicate clearly which phase of the initial calibration the receiver is in In Phase IV good DR performance can already be expected as all sensors are calibrated Still further fine calibration will be ongoing w...

Page 23: ...r e g change of tires from summer to winter tires the system will recover itself If the miscalibration leads to a sensor integrity check error the receiver reports GPS only solutions see also Section3 1 1 2 a reset of the calibration data and new initial calibration is required 3 1 5 Storage of Parameters To maintain a high degree of dead reckoning navigation accuracy all dynamic DR calibration pa...

Page 24: ...te Do not confuse this with Static Hold Mode from the GPS Kalman Filter 3 2 Power Saving Modes Please note that FIXNOW is not supported by the LEA 4R TIM 4R 3 3 Antenna and Antenna Supervisor For information regarding the antenna and antenna supervisor please refer to the ANTARIS 4 System Integration Manual 5 3 3 1 Open Circuit Detect AADET_N is assigned to different pins for TIM 4R and the other ...

Page 25: ...e to the application environment Do not change for LEA 4R TIM 4R Allow Almanac Navigation Enable Almanac Navigation without ephemeris data as a degraded mode to realize fast fixes with reduced position accuracy Navigation Input Filters Applies a mask to the input parameters of the navigation engine to filter the input data It screens potentially poor quality data preventing its use in the navigati...

Page 26: ...sor based Dead Reckoning GPS solutions u blox offers Dead Reckoning enabled GPS modules LEA 4R TIM 4R It allows high accuracy position solutions for automotive applications at places with poor or no GPS coverage This technology relies on additional inputs from a turn rate sensor gyro and a speed sensor odometer or wheel tick 4 1 6 Almanac Navigation The satellite orbit information retrieved from a...

Page 27: ...only 3 satellites Set this value to 1 single satellite for timing applications LEA 4T only Max SVs Uses at most n satellites for a navigation solution Initial Min SV Minimum number of satellites which must be available before the first position fix will be calculated Min C No A satellite with a C N0 below this limit is not used for navigation Initial Min C No Minimum C N0 for the initial fix Only ...

Page 28: ...ive limit Table 13 Navigation Output Filter parameter 4 1 9 Position Quality Indicators 4 1 9 1 NMEA Valid Flag Position Fix Indicator A position fix is declared as valid if all of the conditions below are met Position fix with at least 3 satellites 2D or 3D fix In order to ensure a good accuracy the ANTARIS 4 GPS Technology does not support 1D fixes The 3D Position Accuracy Estimate needs to be b...

Page 29: ...ential GNSS Fix E Estimated Dead Reckoning Fix 1 1 2 2 2 3 3 GSA Nav Mode 1 Fix Not available 2 2D Fix 3 3D Fix V V V A A A A Status A Data VALID V Data Invalid Navigation Receiver Warning N N E E A D A D A D RMC Mode Indicator N No Fix A Autonomous GNSS Fix D Differential GNSS Fix E Estimated Dead Reckoning Fix N N E E A D A D A D VTG Mode Indicator N No Fix A Autonomous GNSS Fix D Differential G...

Page 30: ... UBX Valid Flag Position Fix Indicator UBX protocol provides status information in abundance Table 19 lists the position fix flags Status Field Message Enumeration Description GPSfix NAV STATUS NAV SOL 0x00 0x01 0x02 0x03 0x04 No Fix Dead Reckoning only 2D fix 3D fix GPS Dead Reckoning combined Flags NAV STATUS NAV SOL 0x01 0x02 0x04 0x08 GPS fix OK i e within PDOP Position Accuracy Masks DGPS use...

Page 31: ...Table 21 Status Information in UBX Protocol 4 1 10 DGPS Differential GPS For information about the RTCM protocol refer to ANTARIS 4 System Information Manual 5 4 1 11 SBAS Satellite Based Augmentation Systems Please note that the LEA 4 TIM 4R does not support SBAS 4 1 12 RAIM Receiver Autonomous Integrity Monitoring RAIM is a process where the GPS unit itself uses various techniques to monitor the...

Page 32: ... Digital self test Software Download verification of FLASH firmware etc Measurement of voltages and currents Measurement of RF characteristics e g C No Figure 17 Automatic Test Equipment for Module Tests 5 2 Test Parameters for OEM Manufacturer Based on the test done by u blox with 100 coverage it is obvious that an OEM manufacturer doesn t need to repeat firmware tests or measurements of the GPS ...

Page 33: ...ower up the DUT Device Under Test and allow enough time for the acquisition 4 Read the C No value from the NMEA GSV or the UBX NAV SVINFO message e g with u center AE 5 Reduce the power level by 10dB and read the C No value again 6 Compare the results to a Golden Device or an ANTARIS 4 GPS EvalKit 5 3 2 Go No go tests for integrated devices The best test is to bring the device to an outdoor positi...

Page 34: ...the duration of the last update period shall correspond to the input signal frequency Period s Speedpulse fin 5 4 3 Gyroscope Rate Input Three different DC voltages 1 0 V 2 5 V and 4 0 V shall be applied to the rate input input of the A D converter and the measurements will be read out with the UBX NAV EKFSTATUS message The voltage applied to the rate input can be measured using the mean gyro valu...

Page 35: ... Support Tools For information on various PC Support Tools for the LEA 4R TIM 4R please see the ANTARIS 4 System Integration Manual 5 LEA 4R TIM 4R System Integration Manual Reference Design PC Support Tools GPS G4 MS4 05043 Page 35 ...

Page 36: ...design it is advisable to change the value of some resistors see Table 23 Please see the reference schematics in Appendix Error Reference source not found for positioning of the resistors Resistor TIM 4R TIM LR R14 18k 47k R32 OR 11 47k R36 5k6 47k R39 OR 12 47k Table 23 Resistor values by migration from TIM LR to TIM 4R The UBX CFG NAV message TIM LR only has been replaced by the UBX CFG NAV2 mes...

Page 37: ... Status Pin not available anymore No difference otherwise 10 VDD18_OUT Not connected VDD18OUT Not connected No difference 11 to 16 GND GND GND GND No difference 17 RF_IN RF_IN RF_IN RF_IN No difference 18 GND GND GND GND No difference 19 V_ANT 3 0V 5 0V V_ANT 3 0V 5 0V No difference 20 VCC_RF VCC 0 1V VCC_RF VCC 0 1V No difference 21 V_BAT 1 95 3 6V V_BAT 1 50 3 6V Wider voltage range Uncritical f...

Page 38: ... UBX CFG NAV2 Parameter Default setting Unit Range Remark Dynamic Platform Model 3 Automotive 1 Stationary 2 Pedestrian 3 Automotive 4 Sea 5 Airborne 1g 6 Airborne 2g 7 Airborne 4g Allow Almanac Navigation Disabled Enabled Disabled Static Hold Threshold 0 00 m s Navigation Input Filters Initial Min SV 3 3 16 Min SV s 3 3 16 Max SV s 16 3 16 Initial Min C N0 Fix 24 dBHz Standard GPS Min C NO 20 dBH...

Page 39: ... Measurement Period 1000 ms Measurement Rate 1 Cycles Table 35 Output Rates default settings Receiver Manager UBX CFG RXM Parameter Default setting Unit Range Remark GPS Mode Normal Auto Normal Fast Acquisition High Sensitivity Low Power Mode 0 CTM 0 CTM 1 FXN Table 37 Receiver Configuration default settings B 3 Power Saving Modes FixNOW Mode UBX CFG FXN Parameter Default setting Unit Range Remark...

Page 40: ...1 stop bit Autobauding Disabled Enabled Disabled Table 41 Port default settings B 5 Messages UBX CFG MSG UBX Message Type USART1 TARGET1 14 USART2 TARGET2 USB TARGET3 Range Remark NAV POSECEF Out NAV POSLLH Out 1 NAV STATUS Out 1 NAV DOP Out NAV SOL Out 1 NAV POSUTM Out NAV VELECEF Out NAV VELNED Out NAV TIMEGPS Out NAV TIMEUTC Out NAV CLOCK Out NAV SVINFO Out 1 NAV DGPS Out NAV SBAS Out NAV EKFST...

Page 41: ...1 Out NMEA PUBX 03 Out NMEA PUBX 04 Out NMEA PUBX 05 Out NMEA PUBX 06 Out Table 45 NMEA enabled output msg B 6 Messages UBX CFG INF UBX Message Type USART1 TARGET1 16 USART2 TARGET2 USB TARGET3 16 Range Remark INF Error Out 1 INF Warning Out 1 INF Notice Out 1 INF Test Out INF Debug Out INF User Out 1 Table 47 UBX default enabled INF msg 15 The Number entered under Target1 Target2 defines the outp...

Page 42: ... rising 0 disabled 1 falling Pulse Period 1000 ms 1 60 000 Pulse Length 100 ms 1us Pulse Period 0 250 us Time Source 1 GPS time 0 UTC time 1 GPS time Cable Delay 50 ns 2x10 9 us User Delay 0 ns 2x10 9 us Table 51 Timepulse default settings C Reference Design for TIM 4R For a Reference Design for the TIM 4R including design reference schematic bill of material and a reference layout please consult ...

Page 43: ...23 22 21 15 14 13 12 11 1 2 3 4 5 6 7 8 9 10 VDD18OUT EXTINT1 FWD RxD2 TxD2 TxD1 RxD1 BOOT_INT GND VCC GND GND GND GND GND 25 4 0 1 mm 1000 4 mil 25 4 0 1 mm 1000 4 mil 1 9 0 1 mm 75 4 mil 2 8 0 1 mm 110 4 mil 1 277 0 1 mm 50 27 4 mil 1 5 0 1 mm 59 4 mil 3 0 0 3 mm 118 12 mil SPI Figure 19 TIM 4R Dimensions LEA 4R TIM 4R System Integration Manual Reference Design Mechanical Data GPS G4 MS4 05043 P...

Page 44: ...3 14 28 27 26 25 24 23 22 21 20 19 18 17 16 15 Figure 20 LEA 4R Dimensions D 2 Specification Parameter Module Specification LEA 4R 22 4 1mm 881 4mil Length TIM 4R 25 4 1mm 1000 4mil LEA 4R 17 0 1mm 669 4mil Width TIM 4R 25 4 1mm 1000 4mil LEA 4R 3 0 0 3mm 118 12mil Thickness TIM 4R 3 0 0 3mm 118 12mil LEA 4R 1 9 0 1mm 75 4mil Pitch RF pins TIM 4R 1 9 0 1mm 75 4mil LEA 4R 1 277 0 1mm 50 4mil Pitch ...

Page 45: ...tary extension to the NMEA protocol PVT Position Velocity Time SA Selective Availability SBAS Satellite Based Augmentation Systems TIM 4x Placeholder for all ANTARIS 4 GPS modules UBX File extension for u center log file or short form for the UBX protocol UBX Protocol A proprietary binary protocol used by the ANTARIS GPS technology UTM Universal Transverse Mercator u center AE u center ANTARIS Edi...

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