intertechno-cc1101/intertechno_cc1101/__init__.py

import logging
import time

import cc1101

_ADDRESS_LENGTH_BITS = 26
_COMMAND_LENGTH_BITS = 2
_BUTTON_INDEX_LENGTH_BITS = 4
_MESSAGE_LENGTH_BITS = (
    _ADDRESS_LENGTH_BITS + _COMMAND_LENGTH_BITS + _BUTTON_INDEX_LENGTH_BITS
)

# > [...] default PATABLE setting (0xC6).
# "24 Output Power Programming" in CC1101's docs
DEFAULT_POWER_SETTING = 0xC6

_LOGGER = logging.getLogger(__name__)


def _cc1101_transmit(payload: bytes, power_setting: int, repeats: int = 3) -> None:
    with cc1101.CC1101(lock_spi_device=True) as transceiver:
        transceiver.set_base_frequency_hertz(433.93e6)
        transceiver.set_symbol_rate_baud(3942)
        transceiver.set_sync_mode(cc1101.SyncMode.NO_PREAMBLE_AND_SYNC_WORD)
        transceiver.set_packet_length_mode(cc1101.PacketLengthMode.FIXED)
        transceiver.set_packet_length_bytes(len(payload))
        transceiver.disable_checksum()
        transceiver.set_output_power((0, power_setting))  # OOK
        _LOGGER.info("%s", transceiver)
        for _ in range(repeats):
            transceiver.transmit(payload)
            time.sleep(0.08)


def _encode_message(message: int) -> bytes:
    signal = [0b00000100, 0]
    assert 0 <= message < 2 ** _MESSAGE_LENGTH_BITS, message
    for bit_index in reversed(range(_MESSAGE_LENGTH_BITS)):
        if message & (0b1 << bit_index):
            signal.append(0b10000010)
        else:
            signal.append(0b10100000)
    signal.append(0b10000000)
    return bytes(signal)


class RemoteControl:
    def __init__(self, address: int) -> None:
        if not isinstance(address, int):
            raise ValueError(
                "expected {}-bit unsigned integer as address, got {!r}".format(
                    _ADDRESS_LENGTH_BITS, address
                )
            )
        if address < 0:
            raise ValueError("address must not be negative (got {!r})".format(address))
        if address >= 2 ** _ADDRESS_LENGTH_BITS:
            raise ValueError(
                "address must not exceed {} ({}-bit unsigned integer), got {!r}".format(
                    2 ** _ADDRESS_LENGTH_BITS, _ADDRESS_LENGTH_BITS, address
                )
            )
        self._address = address

    def _send_command(
        self, command: int, button_index: int, power_setting: int
    ) -> None:
        assert 0 <= command < 2 ** _COMMAND_LENGTH_BITS
        if not isinstance(button_index, int):
            raise ValueError(
                "expected {}-bit unsigned integer as button index, got {!r}".format(
                    _BUTTON_INDEX_LENGTH_BITS, button_index
                )
            )
        if button_index < 0:
            raise ValueError(
                "button index must not be negative (got {!r})".format(button_index)
            )
        if button_index >= 2 ** _BUTTON_INDEX_LENGTH_BITS:
            raise ValueError(
                "button index must not exceed {} ({}-bit unsigned integer), got {!r}".format(
                    2 ** _BUTTON_INDEX_LENGTH_BITS,
                    _BUTTON_INDEX_LENGTH_BITS,
                    button_index,
                )
            )
        _cc1101_transmit(
            _encode_message(
                (self._address << _COMMAND_LENGTH_BITS | command)
                << _BUTTON_INDEX_LENGTH_BITS
                | button_index
            ),
            power_setting=power_setting,
        )

    def turn_on(
        self,
        button_index: int,
        power_setting: int = DEFAULT_POWER_SETTING,
    ) -> None:
        """
        Consult section "Table 39: Optimum PATABLE Settings
        for Various Output Power Levels and Frequency Bands [...]"
        in CC1101's official documentation for `power_setting`.
        """
        self._send_command(
            command=0b01,
            button_index=button_index,
            power_setting=power_setting,
        )

    def turn_off(
        self,
        button_index: int,
        power_setting: int = DEFAULT_POWER_SETTING,
    ) -> None:
        self._send_command(
            command=0b00,
            button_index=button_index,
            power_setting=power_setting,
        )