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ODB2 and CAN Acquisition Libraries

The intention of this tutorial is to provide a quick method for programming the Arduino DUE CAN shield kit.

arduino-due-canshield-with-2-can-bus-interfaces-1.jpg

buy-from-coppperhill-technologies.jpg

The ODB2 and CAN Acquisition Libraries libraries were designed with continuous message TX/RX (DAQ applications) in mind by implementing a periodic scheduler. The scheduler supports both native DUE CAN ports and allows for one to easily implement a “free-running raw” CAN protocol or perhaps something a bit more layered such as OBD2. An OBD2 implemenation is provided, and logged CAN traffic and screen data are provided in the repository (driveHome. files).

Installation

  1. What you need to do to get it working (assuming a windows installation):
  2. download Arduino IDE R 1.6.x http://www.arduino.cc/en/Main/Software
  3. download all of the files from the togglebit repository: Togglebit GitHub 
  4. After IDE installation, create a new folder called “CAN” under a path C:\Program Files (x86)\Arduino\libraries\
  5. Next drop all files( .c,.h and *.ino) into the new folder (C:\Program Files (x86)\Arduino\libraries\CAN)
  6. Open Arduino IDE 1.6x to Tools->Boards->Boards Manager and download the Adruino SAM (32-bit ARM cortex-M3) boards hardware support kit
  7. Once installed, go to boards select the Arduino DUE board ad the target board.
  8. Opening any of the examples ( *.ino) files will create a new folder.
  9. You will now be able to verify, upload and tryout the examples!

Getting Started with Free Running CAN

To transmit a message five times a second:

```c++

//create the CANport acqisition schedulers

cAcquireCAN CANport0(CAN_PORT_0);

//define a CANFrame object

cCANFrame RAW_CAN_Frame1;

//start CAN ports, set the baud rate here

CANport0.initialize(_500K);

//then set the ID and transmission rate

RAW_CAN_Frame1.ID = 0x100;

RAW_CAN_Frame1.rate = _5Hz_Rate;

//add to the scheduler

CANport0.addMessage(&RAW_CAN_Frame1, TRANSMIT);

// call the scheduler in a 2mS timer iterrupt

CANport0.run(TIMER_2mS);

// manipulate CAN payload in loop() or wherever appropriate

RAW_CAN_Frame1.U.b[0] = i;

```

Getting Started with ODB2 PIDs

For a reference to PIDs, see: wikipedia.org

To get, for instance, the engine RPM:

```c++

//create the CANport acqisition schedulers

cAcquireCAN CANport0(CAN_PORT_0);

//define an OBDParameter object

cOBDParameter OBD_Speed("Speed ", " KPH" , SPEED , _8BITS, false, CURRENT, 1, 0, &CANport0);

//start CAN ports, set the baud rate here

CANport0.initialize(_500K);

// call the scheduler, preferable in an interrupt

CANport0.run(TIMER_2mS);

//show acquired data in loop() wherever appropriate

Serial.print(OBD_EngineSpeed.getName());

Serial.print(OBD_EngineSpeed.getData());

Serial.println(OBD_EngineSpeed.getUnits());

```

Some Tips and Considerations

  • The first revision of code was developed for functionality and not speed. For example, there is only one CAN mailbox implemented. Many many speed efficiencies are yet to be found and optimized.
  • The underlying CAN library provided here "due_can.*" may not be the latest contributions from the DUE forum.
  • Yes, we've hijacked and modified the variants.h file - the OBD2 has only beent tested on one vehicle so far with 11-bit identifiers
  • To create an OBD PID that does not yet exist see the relevant enums in the OBD2.h file.
  • Thanks to collin80 for developing the original due_can.* libraries and ivanseidel for developoing the DUETimer libraries
  • When in doubt, check your wiring and termination resistors ;)

Programming Arduino Getting Started with Sketches

by Simon Monk

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