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Serial

Serial KISS Interface

The serial KISS interface is used to communicate with Terminal Node Controllers that support the KISS protocol. You can see an example of a working configuration in the real interface part of the tutorial.

pax25.interfaces.serial.SerialInterface

Interface for KISS serial interaction.

Source code in pax25/interfaces/serial.py 
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class SerialInterface(Interface[SerialSettings]):
    """
    Interface for KISS serial interaction.
    """

    type = "Serial"
    serial: Serial

    def __init__(self, name: str, settings: SerialSettings, station: "Station") -> None:
        """
        Initialize a serial interface.
        """
        self.name = name
        self.station = station
        self.send_queue: Queue[Frame] = Queue()
        self._settings = settings
        tnc_settings = default_tnc_settings()
        tnc_settings.update(settings.get("tnc_settings", {}))
        self._tnc_settings = tnc_settings
        self._read_loop: Task[None] | None = None
        self._write_loop: Task[None] | None = None
        self.serial = self.initialize_serial()

    def initialize_serial(self) -> Serial:
        """
        Set up the serial interface.
        """
        return Serial(
            self.path,
            baudrate=self.baud_rate,
            bytesize=8,
            parity="N",
            stopbits=1,
            rtscts=self.rtscts,
            dsrdtr=self.dsrdtr,
            xonxoff=self.xonxoff,
        )

    @property
    def settings(self) -> SerialSettings:
        """
        Return the running settings of the serial interface.
        """
        settings = smart_clone(self._settings)
        settings["tnc_settings"] = smart_clone(self._tnc_settings)
        return settings

    @property
    def sudo(self) -> bool:
        """
        Randos over the air shouldn't be superusers.
        """
        return False

    async def reload_settings(self, settings: SerialSettings) -> None:
        """
        Reload the serial interface.
        """
        await self.shutdown()
        self._settings = settings
        tnc_settings = default_tnc_settings()
        tnc_settings.update(settings.get("tnc_settings", {}))
        self._tnc_settings = tnc_settings
        self.serial = self.initialize_serial()
        self.start()

    @property
    def path(self) -> str:
        default_path = "COM1" if os.name == "nt" else "/dev/ttyUSB0"
        return self.settings.get("path", default_path)

    @property
    def baud_rate(self) -> int:
        return self.settings.get("baud_rate", 9600)

    @property
    def timeout(self) -> int:
        return self.settings.get("timeout", 1)

    @property
    def write_timeout(self) -> int:
        return self.settings.get("write_timeout", 2)

    @property
    def rtscts(self) -> bool:
        return self.settings.get("rtscts", False)

    @property
    def dsrdtr(self) -> bool:
        return self.settings.get("dsrdtr", False)

    @property
    def xonxoff(self) -> bool:
        return self.settings.get("xonxoff", False)

    @property
    def exit_kiss(self) -> bool:
        return self.settings.get("exit_kiss", False)

    @property
    def gateway(self) -> bool:
        return self.settings.get("gateway", True)

    @property
    def tx_delay(self) -> bytes:
        return self._tnc_settings["tx_delay"].to_bytes(1, KISS_ENDIAN)

    @property
    def persist(self) -> bytes:
        return self._tnc_settings["persist"].to_bytes(1, KISS_ENDIAN)

    @property
    def slot_time(self) -> bytes:
        return self._tnc_settings["slot_time"].to_bytes(1, KISS_ENDIAN)

    @property
    def full_duplex(self) -> bytes:
        return self._tnc_settings["full_duplex"].to_bytes(1, KISS_ENDIAN)

    @property
    def port(self) -> int:
        return self._tnc_settings["port"]

    @property
    def listening(self) -> bool:
        """
        Returns a bool indicating whether the interface is listening.
        """
        if not self._read_loop:
            return False
        return not self._read_loop.done()

    def start(self) -> None:
        """
        Starts the serial loops.
        """
        if self.exit_kiss:
            self.exit_kiss_mode()
            logger.info("Exit KISS mode invoked. Shutting down immediately.")
            asyncio.ensure_future(self.station.shutdown())
            return
        self._read_loop = asyncio.ensure_future(self.read_loop())
        self._write_loop = asyncio.ensure_future(self.write_loop())

    def send_settings(self) -> None:
        """
        Send the bytes down serial to configure the TNC.
        """
        # Need to write out the bytes to set up the TNC.
        self.serial.write(
            kiss_command(KISS_CMD_TXDELAY, self.port, self.tx_delay)
            + kiss_command(KISS_CMD_PERSIST, self.port, self.persist)
            + kiss_command(KISS_CMD_SLOTTIME, self.port, self.slot_time)
            + kiss_command(KISS_CMD_FULLDUP, self.port, self.full_duplex)
        )

    def exit_kiss_mode(self) -> None:
        """
        Can be used if we need to exit KISS mode, if your TNC supports it.
        """
        self.serial.write(b"\xc0\xff\xc0")

    async def read_loop(self) -> None:
        """
        Connect to the given serial object and then start reading frames.
        """
        async for frame in ax25_frames_from_kiss(build_serial_reader(self.serial)):
            self.station.frame_router.process_frame(self, frame)

    async def write_loop(self) -> None:
        """
        Write loop for serial interface.
        """
        self.send_settings()
        while frame := await self.send_queue.get():
            self.serial.write(kiss_command(KISS_CMD_DATA, self.port, frame.assemble()))

    def send_frame(self, frame: Frame) -> None:
        """
        Send frames out on KISS to the serial device.
        """
        self.send_queue.put_nowait(frame)

    async def shutdown(self) -> None:
        """
        Close the serial connection and stop listening.
        """
        self._read_loop, self._write_loop = await cancel_all(
            [self._read_loop, self._write_loop]
        )
        if self.serial.is_open:
            self.serial.flush()
            self.serial.close()

listening: bool property

Returns a bool indicating whether the interface is listening.

settings: SerialSettings property

Return the running settings of the serial interface.

sudo: bool property

Randos over the air shouldn't be superusers.

__init__(name: str, settings: SerialSettings, station: Station) -> None

Initialize a serial interface.

Source code in pax25/interfaces/serial.py 
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def __init__(self, name: str, settings: SerialSettings, station: "Station") -> None:
    """
    Initialize a serial interface.
    """
    self.name = name
    self.station = station
    self.send_queue: Queue[Frame] = Queue()
    self._settings = settings
    tnc_settings = default_tnc_settings()
    tnc_settings.update(settings.get("tnc_settings", {}))
    self._tnc_settings = tnc_settings
    self._read_loop: Task[None] | None = None
    self._write_loop: Task[None] | None = None
    self.serial = self.initialize_serial()

exit_kiss_mode() -> None

Can be used if we need to exit KISS mode, if your TNC supports it.

Source code in pax25/interfaces/serial.py 
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def exit_kiss_mode(self) -> None:
    """
    Can be used if we need to exit KISS mode, if your TNC supports it.
    """
    self.serial.write(b"\xc0\xff\xc0")

initialize_serial() -> Serial

Set up the serial interface.

Source code in pax25/interfaces/serial.py 
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def initialize_serial(self) -> Serial:
    """
    Set up the serial interface.
    """
    return Serial(
        self.path,
        baudrate=self.baud_rate,
        bytesize=8,
        parity="N",
        stopbits=1,
        rtscts=self.rtscts,
        dsrdtr=self.dsrdtr,
        xonxoff=self.xonxoff,
    )

read_loop() -> None async

Connect to the given serial object and then start reading frames.

Source code in pax25/interfaces/serial.py 
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async def read_loop(self) -> None:
    """
    Connect to the given serial object and then start reading frames.
    """
    async for frame in ax25_frames_from_kiss(build_serial_reader(self.serial)):
        self.station.frame_router.process_frame(self, frame)

reload_settings(settings: SerialSettings) -> None async

Reload the serial interface.

Source code in pax25/interfaces/serial.py 
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async def reload_settings(self, settings: SerialSettings) -> None:
    """
    Reload the serial interface.
    """
    await self.shutdown()
    self._settings = settings
    tnc_settings = default_tnc_settings()
    tnc_settings.update(settings.get("tnc_settings", {}))
    self._tnc_settings = tnc_settings
    self.serial = self.initialize_serial()
    self.start()

send_frame(frame: Frame) -> None

Send frames out on KISS to the serial device.

Source code in pax25/interfaces/serial.py 
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def send_frame(self, frame: Frame) -> None:
    """
    Send frames out on KISS to the serial device.
    """
    self.send_queue.put_nowait(frame)

send_settings() -> None

Send the bytes down serial to configure the TNC.

Source code in pax25/interfaces/serial.py 
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def send_settings(self) -> None:
    """
    Send the bytes down serial to configure the TNC.
    """
    # Need to write out the bytes to set up the TNC.
    self.serial.write(
        kiss_command(KISS_CMD_TXDELAY, self.port, self.tx_delay)
        + kiss_command(KISS_CMD_PERSIST, self.port, self.persist)
        + kiss_command(KISS_CMD_SLOTTIME, self.port, self.slot_time)
        + kiss_command(KISS_CMD_FULLDUP, self.port, self.full_duplex)
    )

shutdown() -> None async

Close the serial connection and stop listening.

Source code in pax25/interfaces/serial.py 
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async def shutdown(self) -> None:
    """
    Close the serial connection and stop listening.
    """
    self._read_loop, self._write_loop = await cancel_all(
        [self._read_loop, self._write_loop]
    )
    if self.serial.is_open:
        self.serial.flush()
        self.serial.close()

start() -> None

Starts the serial loops.

Source code in pax25/interfaces/serial.py 
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def start(self) -> None:
    """
    Starts the serial loops.
    """
    if self.exit_kiss:
        self.exit_kiss_mode()
        logger.info("Exit KISS mode invoked. Shutting down immediately.")
        asyncio.ensure_future(self.station.shutdown())
        return
    self._read_loop = asyncio.ensure_future(self.read_loop())
    self._write_loop = asyncio.ensure_future(self.write_loop())

write_loop() -> None async

Write loop for serial interface.

Source code in pax25/interfaces/serial.py 
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async def write_loop(self) -> None:
    """
    Write loop for serial interface.
    """
    self.send_settings()
    while frame := await self.send_queue.get():
        self.serial.write(kiss_command(KISS_CMD_DATA, self.port, frame.assemble()))