Versatile Engine Management Systems - VEMS wiki

How to set up GPS logging in V3GUI.

If you take a log (that also contains GPS data) of a timed 402m quatermile run, please publish for analysis and verification (60 feet time is also important! mention your GPS type).

1. Set appropriate comm port for GPS and ECU: Go to Settings/Serial Port Config [Screenshot: Serial Port Settings]
2. Check GPS state:
   1. GPS Offline: The application released the comm port and not tring to connect.
   2. GPS not found: Could not open the device.
   3. GPS warning: Comm port Successfuly opened but no data received.
   4. GPS Ok: Comm port Successfuly opened and incoming data received.
3. Check ECU state:
   1. Offilne:
   2. ECU Not detected (but continously trying)
   3. V3 Detected:
4. Start logging: If GPS and V3 ECU has been detected successfuly to start logging press icon in toolbar. The icon should change to The log file created on the log/ folder. The name of the log file is autogenerated ( format: rawECUlog-YYYY.MM.DD-hh.mm.ss.txt example: rawECUlog-2008.01.29-11.29.55.txt)
5. Playback of raw log: To playback rawlog select[Screenshot: Select raw log]
   1. Put some widgets to the screen "press 8 hotkey" or go to Tools/Realtime Values/Group menu an select one [Screenshot: GPS play back]
6. Convert raw log to csv file:
   1. Go to Tools/Raw Log to XLS convert menu: [Screenshot: Raw Log to XLS convert menu]
   2. Select raw log fileS (yes, you can select multiple files to convert) and press convert button. [Screenshot: Raw Log to XLS convert menu2]

The output csv contains the GPS data (GPS data arrived just when the GPS data position column: -2,-1,0,1,2,... shows 0. Expect it 0.3 msec +- 0.1sec old at that time). From this the

• 0m position
• 60feet timestamp
• 402m timestamp

can be determined. The timestamp of the 0m is not precise enough. The RPM-drop might help. But the 60 feet => 402m timestamps (from interpolation) and their difference is most characteristic anyway. More precise and reproducible than it can be measured by most other means.

Accelerating to high speed is very dangerous so be careful and responsible. Check the regulations that apply.

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GPS device

Both our GPS uses NMEA protocol (only baudrate is different). But other than NMEA format can be implemented, if it can be converted to a struct that contains geographical data and speed. (best to take a few lines of examples in TerminalProgram and test on PC).

For the PC, we use a UFO like GPS that has RS232. It takes +5V power from a PS2 connector.

The fujitsu siemens pocketloox n520 PDA has internal GPS.

Document last modified 2008-04-29 10:14:26

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