GPS Module GYSFFMAXB. Application Note

Transcription

1 GPS Module Application Note In case you adopt this module and design some appliance, please ask for the latest specifications to the local sales office. 1/17

2 Table of content Revision log 1. Overview 2. Scope 3. Summary description of this module 3-1. Module configuration 4. Design guide 4-1. Power start up sequence 4-2. Recommended power circuit 4-3. Clock sequence 4-4. Pattern design guide Power supply system Bypass capacitor layout Recommended pattern on RF part GND pattern Antenna matching Unused terminal processing Mounting land pattern for module 4-5. Heat consideration 5. Caution on mounting 6. Antenna design guide 7. Explanation on software 2/17

3 Revision log Revision Date Change history Version Sep Original release Version Apr Updated antenna design guide 1. Overview The content of this material is design guideline to provide stable characteristics of GPS module which is developed and sold by. It is technical data for the purpose of utilization in designing of equipment which adopt module, and module peripheral circuit. In case of designing peripheral circuit or equipment with reference to this material, please make full evaluation of module characteristics at customer s premises before practical application. For any inquiry, please contact our staff. 2. Scope The content of this material is applicable to following product of GPS module which is developed and sold by. 3. Summary description of this module This module is L1 band which is intended to calculate position by using GPS system of US. IC (MT3339) of Mediatek is mounted and high sensitive and high accuracy receiving is available by adoption of our high frequency technology. LNA with ultralow noise, high accuracy TCXO (0.5ppm), and RTC with 10ppm accuracy are embedded as peripheral circuit, and intermittent operation, Logger function are solely processed by module. Since it is F-ROM Version, upon customer s request, modification and addition of functional Pin is available by modification of GPS engine and Firm change. From above fact, by mounting this module, GPS function could be enabled without strain to the SET system. 3/17

4 3-1. Module configuration ANT Module UART NMEA data LNA Saw Host X tal MT3339 Power TCXO F-ROM 4. Design guide 4-1. Power start up sequence Power supply sequence to operate module is quite simple. As below mentioned, sequence is arranged to input VDD3V3_Backup first, setup VDD3V3 after interval over 100msec. VDD3V3_BACKUP 100mse VDD3V3 100msec RESET 1500msec UART I/F ACTIVE Power-on Timing 10msec RESET RESET Pulse Width 4/17

5 20msec VDD3V3_BACKUP 100msec VDD3V3 2.8V 10msec 0.5V RESET UART I/F ACTIVE Power-off Timing 5/17

6 4-2. Recommended power circuit As module power supply, there are power supplies, VDD3V3_BACKUP, VDD3V3. VDD3V3_BACKUP power supply is RTC power supply which is supplied to RTC circuit and nvram. Therefore, power supply shall be always ON, and it is preferable to concurrently use button cell. Antenna ANT HOST_TXD UART_RXD GPS_PW 3.3V_ LDO VIN VOUT HOST_RXD UART_TXD RESET GPS_EN 100k CE VSS GIO Schottky Diode Schottky Diode 2.2uF TIMER GND Coin Battery VDD3V3_ BACKUP VDD3V3 2.2uF 2.2uF 30pF Bypass capacitors for module shall be placed close to the power supply terminal (VDD3V3, VDD3V3_BACKUP). Input ripple to VDD3V3_MAIN and BACKUP, LDOIN shall be under 50mVpp. * During board designing, please pay attention to allowable dissipation (and heat due to dissipation). 6/17

7 4-3. Clock sequence For clock sequence, please refer to 4-1.Power start up sequence. - For operation of CPU, Slow clock is needed at first, and it is required to have oscillation of RTC (32.768kHz). Therefore, please make supply to RTC power supply first. Then, by application of 3.3Volt, 2.8Volt is generated, TCXO oscillated according to sequence within module. Since transmitter is mounted In this module, normal oscillation is available by following normal power supply sequence Pattern design guide Since GPS handles signal with quite low thermal noise level, caution shall be taken against noise including temperature. Therefore, first, it shall not be placed near heat source such as power supply or circuit with high power signal. Ambient temperature will rise which may increase thermal noise, and deteriorate C/N of GPS signal. Secondly, it shall not be placed near circuit such as DC-DC power supply which may elevate Noise flower Power supply system Bypass capacitors on each power supply line shall be placed close to power supply terminals of module. Since capacitance will be affected by quality of power supply, optimum constant shall be required. Regarding VDD3V3_MAIN(3.0v-4.3v) design with significant line width (over 0.5mm), and via land, via diameter with significant allowance shall be considered. VDD Via diameter over 0.2mm is recommended. Line width over 0.5mm is recommended. Module * If significant via diameter is not ensured, via quantity shall be increased. * Bypass capacitors with smaller capacitance shall be placed close to module. 7/17

8 Bypass capacitor layout It shall be grounded in combination of small capacitance (about 10pF), large capacitance (1uF to 10uF). GND of bypass capacitor shall be close to adjacent module GND to enable shortest closed loop Recommended pattern on RF part RF output impedance for our module is 50 ohm. In case of wiring to antenna, please make design of RF line as 50 ohm strip line. Please keep the area and land pads for matching elements to be placed for ensuring matching with antenna to be used GND pattern Bypass capacitor GND for power supply line, etc. shall be placed in proximity of module GND. Wide GND area shall be reserved to ensure isolation for each layer. e.g.) Surface layer Module high frequency line GND area GND pattern of each layer shall be connected to GND area with large number of via Antenna matching Recommended antenna is AH 316M (L1 band compliant antenna) made by TAIYO YUDEN CO., LTD.. Antenna location, peripheral configuration, and matching circuit have significant effect on radiation characteristics. Please observe following antenna peripheral design guide. <Others> For other digital signals, they shall be away from REF_CLK and RTC, and shall not overlap with these signals between layers Unused terminal processing Unused terminals (RES terminal, unconnected terminal) shall be open in circuit, and land under module shall be created Mounting land pattern dimension Please refer to recommended land pattern specified in Data Report or specification. 8/17

9 4-5. Heat consideration Under high temperature, module could not offer sufficient performance. Therefore, module placement shall be designed to avoid effect from circuit or device which may be thermal source in customer s product. Also, Connection to GND layer on PCB of customer s product (via through-hole, etc.) shall be made to ensure effective heat dissipation of module. Please refer to wiring of our evaluation board. 5. Caution on mounting For mounting of module, please refer to recommended reflow profile specified in Data Report. Please refer separate document, Handling Precaution for more details about desire and conditions for mounting. 6. Antenna Design Guide Original Technology AH 316M This radi-edge antenna has equivalent feature as 12x12x4 patch antenna. 3.2x1.6x0.5mm 1.5GHz: AH 316M PCB (GND) PCB (GND) Keep out area (No GND Area) Keep Out Area (No GND Area) :Only 5 x 6mm(30m m2 ) Antenna Layout :Middle of PCB Edge This minimal area provides the best performance. 9/17

10 Precautions. Surface GND layer around the antenna area should be connected with inner GND layer via through hole.. Matching circuit line should be designed as 50Ω.. Thickness of PCB can be flexible.. Matching circuit should be placed as close as possible to the antenna.. Use of HK1005 and EVK105 series as matching components are highly recommended for the optimized result.. Matching values may be required to get readjusted contingent upon the condition such as proximity to the metal and/or chassis, board size, etc. Recommended land pattern Do not arrange the surface and inside of layer pattern near the antenna mounting area. Example of through hole 10/17

11 Recommended Pattern Layout 3.3 GND Pattern area Unit mm 70 or more 15 or more 15 or more GND Matching circuit 3 components ANT input :50Ω line No Ground Area There should be no ground whatsoever within the antenna mounting area (within the red dotted line) including inner layer. External Dimensions Direction mark Recommended Land Pattern (1) (2) (1) (2) Unit : Unit : mm Terminal No. Terminal Name (1) FEED (2) GND 11/17

12 7. Explanation on software 1. This GPS module outputs NMEA. Therefore, there is no need to calculate position in Host. Command transmission through I/F makes operation such as Hot-start, intermittent operation. List of commands will be separately provided. 2. NMEA output format is listed in Appendix A. 3. MTK NMEA Packet Format is listed in Appendix B. It lists protocol of command. 4. GPS engine, and I/O configuration are stored in F-ROM in module as firmware, and its contents could be easily modified. As Software for Firmware writing, sample version and source code could be provided. * In case of modification in above NMEA output format, NMEA Packet Format, it will be separately updated. 12/17

13 APPENDIX A NMEA OUTPUT FORMAT $GPGGA Global Positioning System Fix Data hhmmss.ss llll.llll a yyyy.yyyy a x xx xx.xx xx.x M xx.x M xxxx xxxx *hh Example $GPGGA, , ,N, ,E,1,9,0.86,66.8,M,15.0,M,,*60 1. Time UTC time 2. Latitude 3. N or S 4. Longitude 5. E or W 6. GPS Quality Indicator 0 - fix not available 1 - GPS fix 2 - Differential GPS fix 7. Number of satellites in view Horizontal Dilution of precision 9. Antenna Altitude above/below mean-sea-level ( geoid ) 10. Units of antenna altitude, meters 11. Geoidal separation, the difference between the WGS-84 earth ellipsoid and mean-sea-level ( geoid ), - means mean-sea-level below ellipsoid 12. Units of geoidal separation, meters 13. Age of differential GPS data, time in seconds since last SC104 type 1 or 9 update, null field when DGPS is not used 14. Differential reference station ID, Checksum 13/17

14 $GPGLL Geographic Position Latitude / Longitude llll.llll a yyyy.yyyy a hhmmss.sss A A *hh Example $GPGLL, ,N, ,E, ,A,A*5E 1. Latitude 2. N or S ( north or South ) 3. Longitude 4. E or W ( East or West ) 5. Time ( UTC ) 6. Status A- Data Valid, V- Data Invalid 7. Mode Indicator A-Autonomous D-Differential E-Estimated N-Data not valid 8. Checksum $GPGSA GNSS DOP and Active Satellites a a xx xx xx xx.xx xx.xx xx.xx *hh Example $GPGSA,A,3,11,31,16,08,23,19,13,27,03,,,,1.18,0.86,0.81*0D 1. Selection mode M Manual forced to operate in 2D or 3D mode A 2D Automatic allowed to automatically switch 2D/3D 2. Mode 1 Fix not available 2 2D 2D (<4 SVs used) 3 3D 3D ( 4SVs used ) 3. ID of 1 st satellite used for fix 4. ID of 2nd satellite used for fix 5. ID of 12 th satellite used for fix 6. PDOP in meters 7. HDOP in meters 8. VDOP in meters 9. Checksum 14/17

15 $GPGSV GNSS Satellites in View x x xx xx xx xxx xx,... *hh Example $GPGSV,3,1,12,11,66,181,11,27,54,297,11,19,47,023,13,08,31,317,13*7D $GPGSV,3,2,12,03,27,046,12,13,15,228,13,31,11,257,12,16,10,104,13*70 $GPGSV,3,3,12,23,08,198,13,28,05,304,,20,03,173,,24,03,205,*7F 1. Total number of messages Range 1 to 3 Depending on the number of satellites tracked, multiple messages of GSV data may be required. 2. message number Range 1 to 3 3. Satellites in view 4. Satellite number Channel 1 5. Elevation in degrees Channel 1 6. Azimuth in degrees to true Channel 1 7. SNR in db Range 0 to 99, ( null when not tracking ) 8. Checksum $GPRMC Recommended Minimum Specific GNSS Data hhmmss.sss A llll.llll a yyyy.yyyy a x.xx xx.xx xxxxxx a *hh Example $GPRMC, ,A, ,N, ,E,0.29,180.91,010505,,,A*62 1. Time (UTC ) 2. Status, V=Navigation receiver warning A=data valid or V= data not valid 3. Latitude 4. N or S 5. Longitude 6. E or W 7. Speed over ground, knots 8. Track made good, degrees true 9. Date, ddmmyy 10. Magnetic Variation, degrees 11. E or W 12. Mode Indicator A Autonomous D- Differential E- Estimated N- Data not valid 13. Checksum 15/17

16 $GPVTG Course Over Ground and Ground Speed xx.xx T M x.x N x.x K a *hh Example $GPVTG,180.91,T,,M,0.29,N,0.55,K,A*37 1. Track Degrees 2. T= True 3. Track Degrees 4. M= Magnetic 5. Speed Knots 6. N=Knotes 7. Speed Kilometers Per Hour 8. K= Kilometers Per Hour 9. Mode Indicator A - Autonomous D- Differential E- Estimated N- Data not valid 10. Checksum 16/17

17 APPENDIX B MTK NMEA Packet Format Preamble Talker ID Pkt Type Data Field * CHK1 CHK2 CR LF Packet Length the maximum length of each packet is restricted to 255 bytes. Packet Contents Preamble One byte character string $ Talker ID Four bytes character string PMTK Pkt Type Three bytes character string From 000 to 999 Data Field The Data Field has variable length depending on the packet type. A comma symbol, must be inserted ahead each data field to help the decoder process the Data Field *: 1 byte character The star symbol is used to mark the end of Data Filed. CHK1, CHK2 Two bytes character string. CHK1 and CHK2 are the checksum of the data between Preamble and *. CR, LF Two bytes binary data. The two bytes are used to identify the end of a packet. MTK NMEA Packet Protocol In order to inform the sender whether the receiver has received the packet, an acknowledge packet PMTK_ACK should return after the receiver receives a packet. Packet Type: 000 PMTK_TEST Packet Meaning:Test packet $PMTK000*32<CR><LF> Packet Type 101 PMTK_CMD_HOT_START Packet Meaning: Hot Restart. Use all available data in the NV Store. Data Field None. Example $PMTK101*32<CR><LF> 17/17