GPSCOMM Critical Design Report

1. GPSCOMMCritical Design Report Taylor Hughes Andy Merritt Adrian Migacz Adam Preeo

2. System Layout GPS RS-232 RF Transceiver RF Transceiver RF RS-232 RS-232 68HC11 68HC11 LCD SPI RS-232 GPS Delorme

3. Laptop Station RF Link to Field Unit Transceiver HC11 Laptop Computer GPS Receiver

4. GPS / Laptop Link Laptop Computer GPS Unit • DeLorme GPS receiver communicates with Serial port on Laptop. • GPS data uses the Rockwell GPS Protocol. • GPS data updates every second. • GPS initialization procedure takes about 30 seconds if there is a “clear” view of the sky.

5. RF / Laptop Link Transceiver HC11 Laptop Computer • Data from transceiver is also in RS232 format, so it can be read in on another serial port. • Data coming from transceiver to laptop contains the NMEA Protocol Data from field GPS unit. • HC11 used to coordinate data between multiple field units and laptop.

6. Serial Connections The base station will use two serial port connections to communicate with external devices for data collection. • Local GPS connection – The local GPS unit uses the Rockwell Protocol for transmitting GPS data, therefore the incoming byte-stream must be parsed to extract the Rockwell GPS data. • Receiver Connection – The receiver will also be connected to the base station by a serial cable. The GPS unit located on the field unit uses the NMEA format for transmitting GPS data. So, the base unit must also be able to parse the incoming byte-stream for NMEA GPS data. The base unit will also send data to the receiver of the serial connection.

7. Base-Station HC11 Pseudocode HC11 initialization procedure LOOP (while not signal.STOP) { FOR(1 to Number of Field units) { Read in data from Field Unit N Send data from Field Unit N to Laptop } Receive data from Laptop FOR(1 to Number of Field units) { Prepare all data for Serial Communication Store Data in memory, indexed by field unit number Send data for Field Unit N to appropriate Transceiver } }

8. Laptop Station Send initialization to GPS units LOOP (while not signal.STOP) { Read in data from local GPS receiver Extract relevant data from local GPS data FOR (1 to Number of Field Units) { Read in data for GPS receiver N from HC11 Extract relevant data from GPS data N } Perform Calculations Send data to field unit over RF link Update GUI with current GPS data }

9. GPS Communication Demonstration

10. U-Blox RCB-LJ GPS receiver board U-Blox ANN Active GPS Antenna Connects to RCB-LJ GPS Parts List

11. GPS Schematic • Data sent from GPS in NMEA TTL serial protocol • Must send initialization sequence

12. ANN Active GPS Antenna Schematic

13. Transceiver Parts List • Low Power Radio Solutions • 2 Easy Radio 900TRS FM transceivers • Easy Radio Development Kit • Antenna • Initialization and Interfacing board

14. 900TRS Schematic and Timing Diagram • Data transmitted serially on 914MHz • Data sent/received, encoded/decoded • Sent out on RS232 and into MAX233

15. GPS and Transceiver Interfacing • GPS transmits NMEA protocol HC11 via TTL serial connection • 9600 Baud • HC11 interfaces with the transceiver via MAX233 serial connection • Transceiver interfaces with base station via RF link • 914 MHz(user programmable) • 9600 Baud(user programmable)

16. Current GPS and Transceiver Data Flow Initial data flow for testing purposes. Final data flow will include HC11 GPS data converted to NMEA protocol and setup to transmit Data flow converted to and from TTL and RS232 Data sent and Received from base station GPS Receiver Transceiver MAX233 Received data sent to memory on microcontroller Data encoded/decoded and Tx/Rx at 914MHz. Data sent out at RS232 protocol

17. Micro-controller Data Flow HC11 Code Xilinx Boot Code EPROM GPS Data PROM HC11 Xilinx SRAM Transceiver Data Data Storage Memory Mapping

18. Microcontroller Data • Motorola 68HC11 MCU (52-pin PLCC) • 8-bit Data Bus, 16-bit Address Bus • 64k Addressing Space • SCI (Serial Communications Interface) • GPS and Transceiver data • SPI (Serial Peripheral Interface) • LCD interface

19. MCU Characteristics

20. Micro-controller Components List

21. CPU

22. HC11 timing diagrams

23. External EPROM and SRAM

24. Memory Mapping/CS for external devices AS, R/W’, E pins from MCU Decoder and Logic programmed in Xilinx Project Manager Tentative Memory Layout Memory Mapping and Layout 0H 512 Bytes Internal RAM 0000H - 01FFH 1000H 64 Byte Register Block 1000H -103FH 2000H External SRAM 2000H - 3500H 3000H External EPROM 3000H-A600H B600H 512 Bytes EEPROM B600H - B7FFH C000H Extra EPROM, interrupt vectors, I/O for external devices C000H-EFFFH Reset Vector FFFEH - FFFFH FFFFH

25. Xilinx FPGA

26. HC11 Field Unit Pseudocode Initialize HC11 -Define addresses of external components LOOP(While not signal.STOP) { Read in GPS Data from GPS to Memory Read GPS Data from Memory and Send over RF-Link to Base Station Read LCD Data from RF-Link and store in memory Read LCD Data from Memory and send to LCD via SPI }

27. Power Components • TTL – RS232 Voltage Converter • MAX233 • Converts TTL and RS232 logic • Voltage Regulator • 7805CT • Steps 12 volts down to 5 volts • Supplies all components on mobile unit

28. LCD • 4x16 character display from Crystal fontz • Serial SPI interface. This will interface with HC11 • SPI requires ASCII protocol to Note: • Slow LCD reaction time – update speed about 16ms = 63Hz. • Clock runs at max frequency of 18 kHz • Backlight takes 5V, 600mA- need separate source

29. LCD - SPI timing diagrams

30. Division of Labor

31. Schedule

32. Parts Price List • LCD Screen - $75 • Transceivers - $200 • GPS Board - $160 • Miscellaneous - $10 • TOTAL - $445 • Opportunity to Work in the basement of the Engineering Center - PRICELESS