FireflyApi2 CAN

3.3.3 CAN usage

Before using, you need to understand the main functions and usage of CanFilter, CanMessage, CanMessageListener and CanSocket.

CanFilter

Constructor：public CanFilter(final int mask, final int filter)
Description：Used filter the received frame information
Parameters：mask  Mask
　　　　　　filter  Frame ID
Example：
//No filtering
CanFilter[] nofilters = new CanFilter[0];

//Only frames with ID 0x400 and 0x410 are received
CanFilter[] filters = new CanFilter[]{new CanFilter(0xfff, 0x400), new CanFilter(0xfff, 0x410)};

CanMessage

Constructor：public CanMessage(final boolean isEFF, final boolean isRTR, final int id, final byte[] data)
Description：Used to store frame information
Parameters：isEFF true(Extended frame)/false(Standard frame)
　　　　　　isRTR  true(Remote frame)/false( Data frame)
　　　　　　id  Frame Id
　　　　　　data Frame Data
Example：
//Store one frame of information, id is 0x100, Standard frame, Data frame,
//Data are {0x01,0x02,0x03,0x04,0x05,0x6,0x7}, Frame information with length of 7
boolean isEFF = false;
boolean isRTR = false;
int canid = 0x100;
byte[] data = new byte[] {(byte)1, (byte)2, (byte)3, (byte)4, (byte)5, (byte)6,(byte)7};
CanMessage message = new CanMessage(isEFF, isRTR, canid, data);

• Get the ID of frame information

  Function：public final int getRawId()
  Description：Get the ID of frame information
  Example：
  int can_id = message.getRawId();

• Get the data of frame information

  Function：public final byte[] getData()
  Description：Get the data of frame information
  Example：
  byte[] data = message.getData();

• Frame information strings

  Function：public final String toString()
  Description：Frame information strings
  Example：
  Log.i("debug", message.toString());

CanMessageListener

Function：public void rxedCanMessage()
Description：Processing interface function for receiving can information
Example：
public class TestCanHelper implements CanMessageListener {
    public final void rxedCanMessage(final CanMessage message)
    {
        Log.i(TAG, message.toString());
    }
}

CanSocket

• Open CAN device

  Function：public int canDeviceOpen(final String canDevice)throws IOException
  Description：Open CAN device，get socket
  Para：canDevice CAN device
  Return：socket, return -1 if failed
  Example：
  int socket = mCanSocket.canDeviceOpen("can0");

• Initialize receive task

  Function：public void initReceiveTask(final int socket, CanFilter[] filters)
  Description：Initialize receive task
  Parameters：socket Socket
  　　　　　　filters  Filters
  Example：
  mCanSocket.initReceiveTask(mRxSocket, filters);

• Start receive task

  Function：public boolean startReceiveTask()
  Description：Start receive task
  Return：true(success)/false(fail)
  Example：
  boolean result =  mCanSocket.startReceiveTask();

• Stop receive task

  Function：public boolean stopReceiveTask()
  Description：Stop receive task
  Return：true(success)/false(fail)
  Example：
  boolean result =  mCanSocket.stopReceiveTask();

• Send frame information

  Function：public void transmit(CanMessage message, int socket)throws IOException
  Description：Send frame information
  Parameters：message Frame information
  　　　　　　socket Socket
  Example：
  mCanSocket.transmit(message, mTxSocket);

• Get the Status of receiving task

  Function：public boolean RxTaskState()
  Description：Get the Status of receiving task
  Return：true Receive task is running
  　　　　false Receive task is stopped
  Example：
  boolean state = mCanSocket.RxTaskState();

• Close CAN device

  Function：public void closeDevice(final int socket, final String canDevice)
  Description：Close CAN device
  Parameters：canDevice CAN device
  Example：
  mCanSocket.closeDevice(socket, "can0");

• Add receive listener

  Function：public void addMessageListener(final CanMessageListener canMessageListener)
  Description：Add receive listener
  Parameters：canMessageListener Receive listener
  Example：
  mCanSocket.addMessageListener(this);

• Remove receive listener

  Function：public void removeMessageListener(final CanMessageListener canMessageListener)
  Description：Remove receive listener
  Parameters：canMessageListener Receive listener
  Example：
  mCanSocket.removeMessageListener(this);

• Clear receive listener

  Function：public void clearMessageListeners()
  Description：Clear receive listener
  Example：
  mCanSocket.clearMessageListeners();

• Set baud rate

  Function：public static boolean setCanBaudRate(String canDevice, String baudrate)
  Description：Set baud rate
  Parameters：canDevice CAN device
  　　　　　　baudrate baud rate
  Return：true(success)/false(fail)
  Example：
  boolean result = CanSocket.setCanBaudRate("can0", "500000"); // can0 baud rate is 500Kbps

• Get CAN device

  Function：public static String[] getCanDeviceArr()
  Description：Get CAN device
  Return：Available CAN devices
  Example：
  String[] canDeviceArr = CanSocket.getCanDeviceArr();

Simple usage example

import android.util.Log;
import com.firefly.api2.can.CanFilter;
import com.firefly.api2.can.CanMessage;
import com.firefly.api2.can.CanMessageListener;
import com.firefly.api2.can.CanSocket;
import java.io.IOException;

public class CanTest implements CanMessageListener {
    private static String TAG = "CanTest";
    private CanSocket mCanSocket = new CanSocket();
    private int txSocket, rxSocket;

    public CanTest(){}

    public void send()throws IOException {
        boolean isEFF = false;
        boolean isRTR = false;
        int id = 0x100;
        byte[] data = new byte[] {(byte)1, (byte)2, (byte)3, (byte)4, (byte)5, (byte)6,(byte)7, (byte)8};
        CanMessage message = new CanMessage(isEFF, isRTR, id, data);
        CanSocket.setCanBaudRate("can0", "500000");
        txSocket = mCanSocket.canDeviceOpen("can0");
        mCanSocket.transmit(message,txSocket);
        mCanSocket.closeDevice(txSocket, "can0");
    }

    public void receive()throws IOException{
        CanFilter[] filter = new CanFilter[0];
        CanSocket.setCanBaudRate("can1", "500000");
        int rxSocket = mCanSocket.canDeviceOpen("can1");
        mCanSocket.initReceiveTask(rxSocket, filter);
        mCanSocket.clearMessageListeners();
        mCanSocket.addMessageListener(this);
        mCanSocket.startReceiveTask();
    }

    public void stopTask(){
        mCanSocket.stopReceiveTask();
        mCanSocket.removeMessageListener(this);
        mCanSocket.closeDevice(rxSocket, "can1");
    }

    @Override
    public void rxedCanMessage(final CanMessage message){
        Log.d(TAG, "rxedCanMessage: " + message.toString());
    }
}