# linlib

The following sections contain sample code for inspiration on how to use Kvaser Python linlib.

## Basic master slave usage

This code opens up one master and one slave, sets bitrate and then the slave sends a wakeup message to the master.

    # import the linlib wrapper from the canlib package
    from canlib import linlib

    # open the first channel as a Master
    master = linlib.openChannel(channel_number=0,
                                channel_type=linlib.ChannelType.MASTER)

    # open the next channel as a Slave
    slave = linlib.openChannel(channel_number=1,
                               channel_type=linlib.ChannelType.SLAVE)

    # print information about device firmware version
    print(master.getFirmwareVersion())

    # setup bitrate
    master.setBitrate(10000)
    slave.setBitrate(10000)

    # activate the LIN interface by going bus on
    master.busOn()
    slave.busOn()

    # send a wakeup frame from the slave
    slave.writeWakeup()

    # read the frame when it arrives at the master
    frame = master.read(timeout=100)
    print(frame)

    # go bus off
    master.busOff()
    slave.busOff()

## Sending message from master

Our next example uses two shorthand helper functions to open the channels. We then send some messages from the master and see that they arrive.

    from canlib import linlib, Frame

    # open the first channel as Master, using helper function
    master = linlib.openMaster(0)

    # open the next channel as a Slave, using helper function
    slave = linlib.openSlave(1)

    # go bus on
    master.busOn()
    slave.busOn()

    # send some messages from master
    NUM_MESSAGES = 2
    for i in range(NUM_MESSAGES):
        master.writeMessage(Frame(id_=i, data=[1, 2, 3, 4, 5, 6, 7, 8]))
    master.writeSync(100)

    # print the received messages at the slave
    for i in range(NUM_MESSAGES):
        frame = slave.read(timeout=100)
        print(frame)

    # the master should also have recorded the messages
    for i in range(NUM_MESSAGES):
        frame = master.read(timeout=100)
        print(frame)

    # go bus off
    master.busOff()
    slave.busOff()

## Requesting LIN 2.0 message

As a last example, let’s look at using LIN 2.0 and setting up a message, using the `Frame` object, on the slave which is then requested by the master.

    from canlib import linlib, Frame

    ID = 0x17
    DATA = bytearray([1, 2, 3, 4])

    # open the first channel as Master, using helper function
    master = linlib.openMaster(0, bps=20000)

    # open the next channel as a Slave, using helper function
    slave = linlib.openSlave(1)

    master.busOn()
    slave.busOn()

    # configure channels to use LIN 2.0
    slave.setupLIN(flags=linlib.Setup.ENHANCED_CHECKSUM | linlib.Setup.VARIABLE_DLC)
    master.setupLIN(flags=linlib.Setup.ENHANCED_CHECKSUM | linlib.Setup.VARIABLE_DLC)

    # setup a message in the slave
    slave.updateMessage(Frame(id_=ID, data=DATA))

    # request the message and print it
    master.requestMessage(ID)
    frame = master.read(timeout=100)
    print(frame)

    # clear the message
    slave.clearMessage(0x17)

    # we should now get an empty message
    master.requestMessage(0x17)
    frame = master.read(timeout=100)
    print(frame)

    # go bus off
    master.busOff()
    slave.busOff()