# Send Random Messages on a Channel

    """pinger.py -- Send random CAN messages based on a database

    This script uses canlib.canlib and canlib.kvadblib to send random messages from
    a database with random data.

    It requires a CANlib channel a connected device capable of sending CAN
    messages, something that receives those messages, and a database to inspect for
    the messages to send.

    Messages can be received and printed by e.g. the dbmonitor.py example script.

    """
    import argparse
    import time
    import random

    from canlib import canlib, kvadblib

    def set_random_framebox_signal(db, framebox, signals):
        sig = random.choice(signals)
        value = get_random_value(db, sig)
        framebox.signal(sig.name).phys = value

    def get_random_value(db, sig):
        limits = sig.limits
        value = random.uniform(limits.min, limits.max)

        # round value depending on type...
        if (
                sig.type is kvadblib.SignalType.UNSIGNED or
                sig.type is kvadblib.SignalType.SIGNED
        ):
            # ...remove decimals if the signal was of type unsigned
            value = int(round(value))
        else:
            # ...otherwise, round to get only one decimal
            value = round(value, 1)

        return value

    def ping_loop(channel_number, db_name, num_messages, quantity, interval, seed=0):
        db = kvadblib.Dbc(filename=db_name)

        ch = canlib.openChannel(channel_number, canlib.canOPEN_ACCEPT_VIRTUAL)
        ch.setBusOutputControl(canlib.canDRIVER_NORMAL)
        ch.setBusParams(canlib.canBITRATE_1M)
        ch.busOn()

        random.seed(seed)

        if num_messages == -1:
            used_messages = list(db)
        else:
            used_messages = random.sample(list(db), num_messages)

        print()
        print("Randomly selecting signals from the following messages:")
        print(used_messages)
        print("Seed used was " + repr(seed))
        print()

        while True:
            # Create an empty framebox each time, ignoring previously set signal
            # values.
            framebox = kvadblib.FrameBox(db)

            # Add all messages to the framebox, as we may use send any signal from
            # any of them.
            for msg in db:
                framebox.add_message(msg.name)

            # Make a list of all signals (which framebox has found in all messages
            # we gave it), so that set_random_framebox_signal() can pick a random
            # one.
            signals = [bsig.signal for bsig in framebox.signals()]

            # Set some random signals to random values
            for i in range(quantity):
                set_random_framebox_signal(db, framebox, signals)

            # Send all messages/frames
            for frame in framebox.frames():
                print('Sending frame', frame)
                ch.writeWait(frame, timeout=5000)

            time.sleep(interval)

    if __name__ == '__main__':
        parser = argparse.ArgumentParser(
            description="Send random CAN message based on a database.")
        parser.add_argument('channel', type=int, default=0, nargs='?', help=(
            "The channel to send messages on."))
        parser.add_argument('--db', default="engine_example.dbc", help=(
            "The database file to base messages on."))
        parser.add_argument('-Q', '--quantity', type=int, default=5, help=(
            "The number of signals to send each tick."))
        parser.add_argument('-I', '--interval', type=float, default=0.2, help=(
            "The time, in seconds, between ticks."))
        parser.add_argument('-n', '--num-messages', type=int, default=-1, help=(
            "The number of message from the database to use, or -1 to use all."))
        parser.add_argument('-s', '--seed', nargs='?', default='0', help=(
            "The seed used for choosing messages. If possible, will be converted to an int. If no argument is given, a random seed will be used."))
        args = parser.parse_args()

        if args.seed is None:
            seed = None
        else:
            try:
                seed = int(args.seed)
            except ValueError:
                seed = args.seed

        ping_loop(
            channel_number=args.channel,
            db_name=args.db,
            num_messages=args.num_messages,
            quantity=args.quantity,
            interval=args.interval,
            seed=args.seed,
        )

## Description

Note

There must be some process reading the messages for `pinger.py` to work (see e.g. Monitor a Channel Using a Database).

`ping_loop` will first extract a random list of messages (see Randomness), and then enter a loop that creates a new `canlib.kvadblib.FrameBox` before adding some random signals with random values (the quantity specified by the `quantity`/`--quantity` argument).

Adding random signals is done with `set_random_framebox_signal`, which picks a random signal from the framebox, and `get_random_value` which inspects the given signal and provides a random value based on the signal’s definition.

Finally, the loop pauses for `interval`/`--interval` seconds between sending messages.

### Randomness

The random selection of messages is done with the `seed`/`--seed` and `num_messages`/`num-messages` arguments. If `num_messages` is `-1`, all messages from the database will be used. Otherwise, `num_message` specifies the number of messages to be randomly picked from the database.

The `seed` argument will be sent to `random.seed` before the messages are selected (which is done with `random.sample`), which means as long as the seed remains the same, the same messages are selected. The `seed` can also be set to `None` for a pseudo-random seed.

## Sample Output

    Randomly selecting signals from the following messages:
    [Message(name='EngineData', id=100, flags=<MessageFlag.0: 0>, dlc=8, comment=''), Message(name='GearBoxInfo', id=1020, flags=<MessageFlag.0: 0>, dlc=1, comment='')]
    Seed used was '0'

    Sending frame Frame(id=1020, data=bytearray(b'\x00'), dlc=1, flags=<MessageFlag.0: 0>, timestamp=None)
    Sending frame Frame(id=100, data=bytearray(b'\x00\x00\x16]\x00\x00\x00\x00'), dlc=8, flags=<MessageFlag.0: 0>, timestamp=None)
    Sending frame Frame(id=1020, data=bytearray(b'\x00'), dlc=1, flags=<MessageFlag.0: 0>, timestamp=None)
    Sending frame Frame(id=100, data=bytearray(b'\x00\x00\x00\xdd\x00\x00\x00\x00'), dlc=8, flags=<MessageFlag.0: 0>, timestamp=None)
    Sending frame Frame(id=1020, data=bytearray(b'\x00'), dlc=1, flags=<MessageFlag.0: 0>, timestamp=None)
    Sending frame Frame(id=100, data=bytearray(b'\x00\x00\x00\xe0\x00\x00`\t'), dlc=8, flags=<MessageFlag.0: 0>, timestamp=None)
    Sending frame Frame(id=1020, data=bytearray(b'\x04'), dlc=1, flags=<MessageFlag.0: 0>, timestamp=None)
    Sending frame Frame(id=100, data=bytearray(b'f\x07\n\x00\x00\x00\x00\x00'), dlc=8, flags=<MessageFlag.0: 0>, timestamp=None)
    Sending frame Frame(id=1020, data=bytearray(b'\x00'), dlc=1, flags=<MessageFlag.0: 0>, timestamp=None)
    Sending frame Frame(id=100, data=bytearray(b'\x0c\x15-\x00\x00\x00\x00\x00'), dlc=8, flags=<MessageFlag.0: 0>, timestamp=None)