PyRoombaAdapter.py

"""
A Python adapter module for Roomba Open Interface

This module is based on the document: iRobot® Roomba 500 Open Interface (OI) Specification
- Link https://www.irobot.lv/uploaded_files/File/iRobot_Roomba_500_Open_Interface_Spec.pdf

"""
import math
import sys
from time import sleep

import serial  # pyserial


class PyRoombaAdapter:
    """
    Adapter class for Roomba Open Interface

    The constructor connects serial port and change the mode to safe mode

    :param string port: Serial port path

    :param int bau_rate: bau rate of serial connection (default=115200)

    :param float time_out_sec: read time out of serial connection [sec] (default=1.0)

    :param float wheel_span_mm: wheel span of Roomba [mm]  (default=235.0)

    Examples:
        >>> PORT = "/dev/ttyUSB0"
        >>> adapter = PyRoombaAdapter(PORT)

    """
    CMD = {"Start": 128,
           "Baud": 129,
           "Safe": 131,
           "Full": 132,
           "Power": 133,
           "Spot": 134,
           "Clean": 135,
           "Max": 136,
           "Drive": 137,
           "Moters": 138,
           "Song": 140,
           "Play": 141,
           "Sensors": 142,
           "Seek Dock": 143,
           "PWM Moters": 144,
           "Drive Direct": 145,
           "Drive PWM": 146,
           "Query List": 149,
           "Stream": 148,
           "Buttons": 165,
           }

    Packet_ID = {
        "OI Mode": 35,
    }

    PARAMS = {
        "STRAIGHT_RADIUS": 32768,
        "MIN_RADIUS": -2000,
        "MAX_RADIUS": 2000,
        "MIN_VELOCITY": -500,
        "MAX_VELOCITY": 500,
    }

    SENSOR = {
        # "Name", (Packet ID, Data Bytes, signed)
        "Wheel Drops": (7, 1, False),
        "Wall": (8, 1, False),
        "Cliff Left": (9, 1, False),
        "Cliff Front Left": (10, 1, False),
        "Cliff Front Right": (11, 1, False),
        "Cliff Right": (12, 1, False),
        "Virtual Wall": (13, 1, False),
        "Wheel Overcurrent": (14, 1, False),
        "Dirt Detect": (15, 1, False),
        "IFR Char Omni": (17, 1, False),
        "Buttons": (18, 1, False),
        "Distance": (19, 2, True),
        "Angle": (20, 2, True),
        "Charging State": (21, 1, False),
        "Voltage": (22, 2, False),
        "Current": (23, 2, True),
        "Temperature": (24, 1, True),
        "Battery Charge": (25, 2, False),
        "Battery Capacity": (26, 2, False),
        # Wall Signal (packet 27) is depreciated
        "Cliff Left Signal": (28, 2, False),
        "Cliff Front Left Signal": (29, 2, False),
        "Cliff Front Right Signal": (30, 2, False),
        "Cliff Right Signal": (31, 2, False),
        "Charging Sources Available": (34, 1, False),
        "OI Mode": (35, 1, False),
        "Song Number": (36, 1, False),
        "Song Playing": (37, 1, False),
        "Number of Stream Packets": (38, 1, False),
        "Requested Velocity": (39, 2, True),
        "Requested Radius": (40, 2, True),
        "Requested Right Velocity": (41, 2, True),
        "Requested Left Velocity": (42, 2, True),
        "Left Encoder Counts": (43, 2, True),
        "Right Encoder Counts": (44, 2, True),
        "Light Bumper": (45, 1, False),
        "Light Bump Left Signal": (46, 2, False),
        "Light Bump Front Left Signal": (47, 2, False),
        "Light Bump Front Center Left Signal": (48, 2, False),
        "Light Bump Front Center Right Signal": (49, 2, False),
        "Light Bump Front Right Signal": (50, 2, False),
        "Light Bump Right Signal": (51, 2, False),
        "IFR Char Left": (52, 1, False),
        "IFR Char Right": (53, 1, False),
        "Left Motor Current": (54, 2, True),
        "Right Motor Current": (55, 2, True),
        "Main Brush Motor Current": (56, 2, True),
        "Side Brush Motor Current": (57, 2, True),
        "Stasis": (58, 1, False)
    }

    def __init__(self, port, bau_rate=115200, time_out_sec=1., wheel_span_mm=235.0):
        self.WHEEL_SPAN = wheel_span_mm
        try:
            self.serial_con = self._connect_serial(port, bau_rate, time_out_sec)
        except serial.SerialException as exc:
            raise ConnectionError(f"Cannot find serial port ('{port}'). Please reconnect it.") from exc

        self.change_mode_to_safe()  # default mode is safe mode
        self.stream_sensors = {}
        sleep(1.0)

    def __del__(self):
        """
        Destructor of PyRoombaAdapter class

        The Destructor make Roomba move to passive mode and close serial connection
        """
        # The `self.serial_con` attribute may not exist if an exception is
        # encountered in `__init__()`
        if getattr(self, "serial_con", None):
            # disconnect sequence
            self._send_cmd(self.CMD["Start"])  # move to passive mode
            sleep(0.1)
            self.serial_con.close()

    def start_cleaning(self):
        """
        Start the default cleaning

        - Available in modes: Passive, Safe, or Full
        - Changes mode to: Passive

        Examples:
            >>> PORT = "/dev/ttyUSB0"
            >>> adapter = PyRoombaAdapter(PORT)
            >>> adapter.start_cleaning()
        """
        self._send_cmd(self.CMD["Start"])
        self._send_cmd(self.CMD["Clean"])

    def start_max_cleaning(self):
        """
        Start the max cleaning

        - Available in modes: Passive, Safe, or Full
        - Changes mode to: Passive

        Examples:
            >>> PORT = "/dev/ttyUSB0"
            >>> adapter = PyRoombaAdapter(PORT)
            >>> adapter.start_max_cleaning()
        """
        self._send_cmd(self.CMD["Start"])
        self._send_cmd(self.CMD["Max"])

    def start_spot_cleaning(self):
        """
        Start spot cleaning

        - Available in modes: Passive, Safe, or Full
        - Changes mode to: Passive

        Examples:
            >>> PORT = "/dev/ttyUSB0"
            >>> adapter = PyRoombaAdapter(PORT)
            >>> adapter.start_spot_cleaning()
        """
        self._send_cmd(self.CMD["Start"])
        self._send_cmd(self.CMD["Spot"])

    def start_seek_dock(self):
        """
        Start seek dock

        - Available in modes: Passive, Safe, or Full
        - Changes mode to: Passive

        Examples:
            >>> PORT = "/dev/ttyUSB0"
            >>> adapter = PyRoombaAdapter(PORT)
            >>> adapter.start_seek_dock()
        """
        self._send_cmd(self.CMD["Start"])
        self._send_cmd(self.CMD["Seek Dock"])

    def change_mode_to_passive(self):
        """
        Change mode to passive mode

        Roomba beeps once to acknowledge it is starting from “off” mode.

        - Available in modes: Passive, Safe, or Full
        """
        self._send_cmd(self.CMD["Start"])

        # TODO implement
        # check mode
        # self.request_data([self.Packet_ID["OI Mode"]])

    def change_mode_to_safe(self):
        """
        Change mode to safe mode

        Safe mode turns off all LEDs.
        If a safety condition occurs, Roomba reverts automatically to Passive mode.

        - Available in modes: Passive, Safe, or Full
        """
        # send command
        self._send_cmd(self.CMD["Start"])
        self._send_cmd(self.CMD["Safe"])

        # TODO implement
        # check mode
        # self.request_data([self.Packet_ID["OI Mode"]])

    def change_mode_to_full(self):
        """
        Change mode to full mode

        Full mode turns off the cliff, wheel-drop and internal charger safety features.
        In Full mode, Roomba executes any command that you send it, even if the internal charger is plugged in,
        or command triggers a cliff or wheel drop condition.

        - Available in modes: Passive, Safe, or Full
        """
        # send command
        self._send_cmd(self.CMD["Start"])
        self._send_cmd(self.CMD["Full"])

        # TODO implement
        # check mode
        # self.request_data([self.Packet_ID["OI Mode"]])

    def turn_off_power(self):
        """
        Turn off power of Roomba

        The mode change to passive mode.

        - Available in modes: Passive, Safe, or Full

        Examples:
            >>> PORT = "/dev/ttyUSB0"
            >>> adapter = PyRoombaAdapter(PORT)
            >>> adapter.turn_off_power()
        """
        # send command
        self._send_cmd(self.CMD["Start"])
        self._send_cmd(self.CMD["Power"])

    def request_data(self, request_id_list):

        if len(request_id_list) == 1:  # single packet
            self._send_cmd(self.CMD["Start"])
            self._send_cmd(self.CMD["Sensors"])
            self._send_cmd(request_id_list[0])
            sleep(0.5)
            print("re:", self.serial_con.read())
            sleep(0.5)

    def move(self, velocity, yaw_rate):
        """
        control roomba at the velocity and the rotational speed (yaw rate)

        Note:
            The Roomba keep a control command until receiving next command

        - Available in modes: Safe or Full
        - Changes mode to: No Change

        - Special cases:
            - Straight = 32768 or 32767 = hex 8000 or 7FFF
            - Turn in place clockwise = -1
            - Turn in place counter-clockwise = 1

        :param float velocity: velocity (m/sec)

        :param float yaw_rate: yaw rate (rad/sec)

        Examples:
            >>> import math
            >>> import time
            >>> PORT = "/dev/ttyUSB0"
            >>> adapter = PyRoombaAdapter(PORT)
            >>> adapter.move(0, math.radians(-10)) # rotate to right side
            >>> time.sleep(1.0) # keep rotate
            >>> adapter.move(0.1, 0.0) # move straight with 10cm/sec
        """
        if velocity == 0:  # rotation
            vel_mm_sec = math.fabs(yaw_rate) * (self.WHEEL_SPAN / 2.0)
            if yaw_rate >= 0:
                radius_mm = 1
            else:  # default is 'CCW' (turning left)
                radius_mm = -1
        elif yaw_rate == 0:
            vel_mm_sec = velocity * 1000.0  # m/s -> mm/s
            radius_mm = self.PARAMS["STRAIGHT_RADIUS"]
        else:
            vel_mm_sec = velocity * 1000.0  # m/s -> mm/s
            radius_mm = vel_mm_sec / yaw_rate

        self.send_drive_cmd(vel_mm_sec, radius_mm)

    def send_drive_cmd(self, roomba_mm_sec, roomba_radius_mm):
        """
        send drive command

        This command controls Roomba’s drive wheels.
        The radius is measured from the center of the turning circle to the center of Roomba.
        A Drive command with a positive velocity and a positive radius makes Roomba drive forward while turning left.
        A negative radius makes Roomba turn toward the right.
        Special cases for the radius make Roomba turn in place or drive straight.
        A negative velocity makes Roomba drive backward.

        :param float roomba_mm_sec: the average velocity of the drive wheels in millimeters per second (-500 – 500 mm/s)

        :param float roomba_radius_mm: the radius in millimeters at which Roomba will turn. (-2000 – 2000 mm)

        Examples:
            >>> PORT = "/dev/ttyUSB0"
            >>> adapter = PyRoombaAdapter(PORT)
            >>> adapter.send_drive_cmd(-100, -1000) # back to the right side
            >>> sleep(2.0) # keep 2 sec
        """
        # print(roomba_mm_sec, roomba_radius_mm, turn_dir)

        roomba_mm_sec = self._adjust_min_max(roomba_mm_sec, self.PARAMS["MIN_VELOCITY"], self.PARAMS["MAX_VELOCITY"])
        velHighVal, velLowVal = self._get_2_bytes(roomba_mm_sec)

        roomba_radius_mm = self._adjust_min_max(roomba_radius_mm, self.PARAMS["MIN_RADIUS"], self.PARAMS["MAX_RADIUS"])
        radiusHighVal, radiusLowVal = self._get_2_bytes(roomba_radius_mm)

        # send these bytes and set the stored velocities
        self._send_cmd([self.CMD["Drive"], velHighVal, velLowVal, radiusHighVal, radiusLowVal])

    def send_drive_direct(self, right_mm_sec, left_mm_sec):
        """
        send drive direct command

        This command lets you control the forward and backward motion of Roomba’s drive wheels independently.
        A positive velocity makes that wheel drive forward, while a negative velocity makes it drive backward.

        - Available in modes: Safe or Full

        :param float right_mm_sec: the velocity of the right drive wheels in millimeters per second (-500 – 500 mm/s)

        :param float left_mm_sec: the velocity of the left drive wheels in millimeters per second (-500 – 500 mm/s)

        Examples:
            >>> PORT = "/dev/ttyUSB0"
            >>> adapter = PyRoombaAdapter(PORT)
            >>> adapter.send_drive_direct(10, 100) # move right forward
            >>> sleep(2.0) # keep 2 sec
        """
        right_mm_sec = self._adjust_min_max(right_mm_sec, self.PARAMS["MIN_VELOCITY"], self.PARAMS["MAX_VELOCITY"])
        right_high, right_low = self._get_2_bytes(right_mm_sec)

        left_mm_sec = self._adjust_min_max(left_mm_sec, self.PARAMS["MIN_VELOCITY"], self.PARAMS["MAX_VELOCITY"])
        left_high, left_low = self._get_2_bytes(left_mm_sec)

        # send these bytes and set the stored velocities
        self._send_cmd([self.CMD["Drive Direct"], right_high, right_low, left_high, left_low])

    def send_drive_pwm(self, right_pwm, left_pwm):
        """
        send drive pwm command

        This command lets you control the forward and backward motion of Roomba’s drive wheels independently.
        It takes four data bytes, which are interpreted as two 16-bit signed values using two’s complement.
        A positive PWM makes that wheel drive forward, while a negative PWM makes it drive backward.

        - Available in modes: Safe or Full

        :param int right_pwm: Right wheel PWM (-255 – 255)

        :param int left_pwm: Left wheel PWM (-255 - 255)

        Examples:
            >>> PORT = "/dev/ttyUSB0"
            >>> adapter = PyRoombaAdapter(PORT)
            >>> adapter.send_drive_pwm(-200, -200) # move backward
            >>> sleep(2.0) # keep 2 sec
        """
        right_pwm = self._adjust_min_max(right_pwm, -255, 255)
        right_high, right_low = self._get_2_bytes(right_pwm)

        left_pwm = self._adjust_min_max(left_pwm, -255, 255)
        left_high, left_low = self._get_2_bytes(left_pwm)

        # send these bytes and set the stored velocities
        self._send_cmd([self.CMD["Drive PWM"], right_high, right_low, left_high, left_low])

    def send_moters_cmd(self, main_brush_on, main_brush_direction_is_ccw,
                        side_brush_on, side_brush_direction_is_inward,
                        vacuum_on
                        ):
        """
        send moters command

        This command controls the motion of Roomba’s main brush, side brush, and vacuum independently.
        Motor velocity cannot be controlled with this command, all motors will run at maximum speed when enabled.
        The main brush and side brush can be run in either direction. The vacuum only runs forward.

        :param bool main_brush_on: main brush on or off

        :param bool main_brush_direction_is_ccw: main brush direction, clockwise or counter-clockwise(default)

        :param bool side_brush_on: side brush on or off

        :param bool side_brush_direction_is_inward: side brush direction, inward(default) or outward

        :param bool side_brush_on: side brush on or off

        :param bool vacuum_on: vacuum on or off

        Examples:
            >>> PORT = "/dev/ttyUSB0"
            >>> adapter = PyRoombaAdapter(PORT)
            >>> adapter.send_moters_cmd(False, True, True, True, False) # side brush is on, and it rotates inward
            >>> sleep(2.0) # keep 2 sec
        """
        cmd = 0  # All initial bit is 0
        if side_brush_on:
            cmd |= 0b00000001
        if vacuum_on:
            cmd |= 0b00000010
        if main_brush_on:
            cmd |= 0b00000100
        if not side_brush_direction_is_inward:
            cmd |= 0b00001000
        if not main_brush_direction_is_ccw:
            cmd |= 0b00010000

        self._send_cmd([self.CMD["Moters"], cmd])

    def send_pwm_moters(self, main_brush_pwm, side_brush_pwm, vacuum_pwm):
        """
        send pwm moters

        This command control the speed of Roomba’s main brush, side brush, and vacuum independently.
        With each data byte, you specify the duty cycle for the low side driver (max 128).
        For example, if you want to control a motor with 25% of battery voltage, choose a duty cycle of 128 * 25% = 32.
        The main brush and side brush can be run in either direction.
        The vacuum only runs forward. Positive speeds turn the motor in its default (cleaning) direction.
        Default direction for the side brush is counterclockwise.
        Default direction for the main brush/flapper is inward.

        - Available in modes: Safe or Full

        :param int main_brush_pwm: main brush PWM (-127 - 127)

        :param int side_brush_pwm: side brush PWM (-127 - 127)

        :param int vacuum_pwm: vacuum duty cycle (0 - 127)

        Examples:
            >>> adapter = PyRoombaAdapter("/dev/ttyUSB0")
            >>> adapter.send_pwm_moters(-55, 0, 0) # main brush is 55% PWM to opposite direction
            >>> sleep(2.0) # keep 2 sec
        """
        main_brush_pwm = self._get_1_bytes(self._adjust_min_max(main_brush_pwm, -127, 127))
        side_brush_pwm = self._get_1_bytes(self._adjust_min_max(side_brush_pwm, -127, 127))
        vacuum_pwm = self._adjust_min_max(vacuum_pwm, 0, 127)
        self._send_cmd([self.CMD["PWM Moters"], main_brush_pwm, side_brush_pwm, vacuum_pwm])

    def send_buttons_cmd(self, clean=False, spot=False, dock=False,
                         minute=False, hour=False, day=False, schedule=False, clock=False):
        """
        send buttons command

        This command lets you push Roomba’s buttons. The buttons will automatically release after 1/6th of a second.

        Note:
            - This API doesn't work on Roomba 690 Model

        :param bool clean: clean button on
        :param bool spot: spot button on
        :param bool dock: dock button on
        :param bool minute: minute button on
        :param bool hour: hour button on
        :param bool day: day button on
        :param bool schedule: schedule button on
        :param bool clock: clock button on
        """
        buttons = 0  # All initial bit is 0
        if clean:
            buttons |= 0b00000001
        if spot:
            buttons |= 0b00000010
        if dock:
            buttons |= 0b00000100
        if minute:
            buttons |= 0b00001000
        if hour:
            buttons |= 0b00010000
        if day:
            buttons |= 0b00100000
        if schedule:
            buttons |= 0b01000000
        if clock:
            buttons |= 0b10000000

        self._send_cmd([self.CMD["Buttons"], buttons])

    def send_song_cmd(self, song_number, song_length, note_number_list, note_duration_list):
        """
        Send song command

        This command lets you specify up to four songs to the OI that you can play at a later time.
        Each song is associated with a song number.
        The Play command uses the song number to identify your song selection.
        Each song can contain up to sixteen notes.
        Each note is associated with a note number that uses MIDI note definitions and a duration
        that is specified in fractions of a second.
        The number of data bytes varies, depending on the length of the song specified.
        A one note song is specified by four data bytes.
        For each additional note within a song, add two data bytes.

        - Available in modes: Passive, Safe, or Full

        :param int song_number: (0-4) The song number associated with the specific song.
                        If you send a second Song command, using the same song number, the old song is overwritten.

        :param int song_length: (1-16) The length of the song, according to the number of musical notes within the song.

        :param list note_number_list: Note Number (31 – 127) The pitch of the musical note Roomba will play,
                                      according to the MIDI note numbering scheme.
                                      The lowest musical note that Roomba will play is Note #31.
                                      Roomba considers all musical notes outside the range of 31 – 127 as rest notes,
                                      and will make no sound during the duration of those notes.

        :param list note_duration_list: Note Duration (0 – 255) The duration of a musical note,
                                        in increments of 1/64th of a second. Example: a half-second long
                                        musical note has a duration value of 32.

        Examples:
            >>> adapter = PyRoombaAdapter("/dev/ttyUSB0")
            >>> # note names
            >>> f4 = 65
            >>> a4 = 69
            >>> c5 = 72
            >>> # note lengths
            >>> MEASURE = 160
            >>> HALF = int(MEASURE / 2)
            >>> Q = int(MEASURE / 4)
            >>> Ed = int(MEASURE * 3 / 16)
            >>> S = int(MEASURE / 16)
            >>> adapter.send_song_cmd(0, 9,
            >>>             [a4, a4, a4, f4, c5, a4, f4, c5, a4],
            >>>             [Q, Q, Q, Ed, S, Q, Ed, S, HALF]) # set song
            >>> adapter.send_play_cmd(0) # play song
            >>> sleep(10.0) # keep playing
        """
        cmd = [self.CMD["Song"], song_number, song_length]
        for (note_number, note_duration) in zip(note_number_list, note_duration_list):
            cmd.append(note_number)
            cmd.append(note_duration)
        self._send_cmd(cmd)

    def send_play_cmd(self, song_number):
        """
        send play command

        This command lets you select a song to play from the songs added to Roomba using the Song command.
        You must add one or more songs to Roomba using the Song command in order for the Play command to work.

        :param int song_number: (0-4)

        Examples:
            >>> adapter = PyRoombaAdapter("/dev/ttyUSB0")
            >>> # note names
            >>> f4 = 65
            >>> a4 = 69
            >>> c5 = 72
            >>> # note lengths
            >>> MEASURE = 160
            >>> HALF = int(MEASURE / 2)
            >>> Q = int(MEASURE / 4)
            >>> Ed = int(MEASURE * 3 / 16)
            >>> S = int(MEASURE / 16)
            >>> adapter.send_song_cmd(0, 9,
            >>>             [a4, a4, a4, f4, c5, a4, f4, c5, a4],
            >>>             [Q, Q, Q, Ed, S, Q, Ed, S, HALF]) # set song
            >>> adapter.send_play_cmd(0) # play song
            >>> sleep(10.0) # keep playing
        """
        self._send_cmd([self.CMD["Play"], song_number])

    def _request_sensor(self, sensor):
        """
        Requests sensor value from Roomba and returns interpreted value.
        :param sensor: Sensor name from SENSOR dictionary
        :return: int sensor value
        """
        self._send_cmd([self.CMD["Sensors"], self.SENSOR[sensor][0]])
        raw = self.serial_con.read(self.SENSOR[sensor][1])
        return int.from_bytes(raw, byteorder='big', signed=self.SENSOR[sensor][2])

    def request_charging_state(self):
        """
        requests charging state

        This function returns one of following Roomba’s current charging states:
        0 = Not charging, 
        1 = Reconditioning Charging, 
        2 = Full Charging, 
        3 = Trickle Charging, 
        4 = Waiting, 
        5 = Charging Fault Condition

        :return: State 0-5
        """
        return self._request_sensor("Charging State")

    def request_voltage(self):
        """
        requests battery voltage

        This function returns the current voltage of Roomba’s battery in millivolts (mV).

        :return: Voltage in range: 0 – 65535 mV
        """
        return self._request_sensor("Voltage")

    def request_current(self):
        """
        requests battery current

        The current in milliamps (mA) flowing into or out of Roomba’s battery. Negative currents indicate that the
        current is flowing out of the battery, as during normal running. Positive currents indicate that the current
        is flowing into the battery, as during charging.

        :return: Current in range: -32768 – 32767 mA
        """
        return self._request_sensor("Current")

    def request_temperature(self, celsius=True):
        """
        requests battery temperature

        This command requests the temperature of Roomba’s battery in degrees Celsius.

        :param bool celsius: true if celsius, false for fahrenheit

        :return: Temperature in range: -128 – 127 Celsius or converted in Fahrenheit
        """
        temp = self._request_sensor("Temperature")
        if not celsius:
            temp = (temp * 1.8) + 32
        return temp

    def request_charge(self):
        """
        requests battery charge

        Returns the current charge of Roomba’s battery in milliamp-hours (mAh). The charge value decreases as the
        battery is depleted during running and increases when the battery is charged.

        :return: Charge in range: 0 – 65535 mAh
        """
        return self._request_sensor("Battery Charge")

    def request_capacity(self):
        """
        requests estimated battery capacity

        Returns the estimated charge capacity of Roomba’s battery in milliamp-hours (mAh).

        :return: Capacity in range: 0 – 65535 mAh
        """
        return self._request_sensor("Battery Capacity")

    def request_distance(self):
        """
        Requests the Roomba's total distance traveled since it was last checked.

        Returns distance traveled in millimeters (mm) since the distance was last requested. Average between both
        wheel distances.

        :return: Output range ± 32768 mm
        """
        return self._request_sensor("Distance")

    def request_angle(self):
        """
        Requests the angular displacement since it was last checked.

        Returns the angle in radians that the Roomba has turned since the angle was last requested.
        Counter-clockwise is defined positive.

        :return: Output range ± 571.9 rad
        """
        # Return a value in radians to remain consistent with the rest of the library
        return math.radians(self._request_sensor("Angle"))

    def request_encoder_counts(self):
        """
        Requests the raw Roomba encoder counts.

        Returns a tuple containing the following: (left count, right count).
        Linear distance traversed by each wheel is defined by the following:
        distance = (π * 72.0 / 508.8) * count.

        :return: A tuple of (left count, right count) in range -32767 - 32768
        """
        return (self._request_sensor("Left Encoder Counts"), self._request_sensor("Right Encoder Counts"))
    
    def request_oi_mode(self):
        """
        requests corrent OI mode

        This function returns the current OI mode. Modes see in following table:
        0 = Off, 
        1 = Passive, 
        2 = Safe, 
        3 = Full

        :return: State 0-3
        """
        return self._request_sensor("OI Mode")

    def data_stream_start(self, sensors_list):
        """
        starts data stream

        This function issues command which starts a stream of data packets. The provided list of packets is sent
        every 15 ms, which is the rate Roomba uses to update data.

        :param list sensors_list: One or more from following sensors: ["Charging State", "Voltage", "Current", "Temperature", "Battery Charge",
                                   "Battery Capacity", "OI Mode"]

        Examples:
            >>> adapter = PyRoombaAdapter("/dev/ttyUSB0")
            >>> adapter.start_data_stream(["Charging State", "Voltage", "Temperature"])
            >>> print(adapter.read_data_stream()) # list with values

        """
        self.stream_sensors = {}
        stream = []
        for sensor in sensors_list:
            self.stream_sensors.update({self.SENSOR[sensor][0]: (self.SENSOR[sensor][1], self.SENSOR[sensor][2])})
            stream.append(self.SENSOR[sensor][0])

        if len(stream) > 0:
            request = [self.CMD["Stream"], len(stream)]
            request.extend(stream)
            self._send_cmd(request)

    def data_stream_stop(self):
        """
        stops data stream

        Stops data stream and resets sensors list.
        """
        self._send_cmd([self.CMD["Stream"], 0])
        self.stream_sensors = {}

    def data_stream_read(self):
        """
        reads data stream

        Reads stream of sensor data packets from Roomba.

        :return: list with sensors values or empty list on error

        Examples:
            >>> adapter = PyRoombaAdapter("/dev/ttyUSB0")
            >>> adapter.start_data_stream(["Charging State", "Voltage", "Temperature"])
            >>> print(adapter.read_data_stream()) # [0, 15530, 20]
        """
        result = []

        header_magic = self.serial_con.read(1)
        if header_magic == b'\x13':
            data_len = self.serial_con.read(1)
            data = self.serial_con.read(int.from_bytes(data_len, byteorder='big'))
            checksum = self.serial_con.read(1)
            calculated_checksum = sum(bytes(header_magic + data_len + data + checksum))
            if (calculated_checksum & 0xFF) == 0:
                data_pos = 0
                while data_pos < len(data):
                    packet_id = int.from_bytes(data[data_pos:data_pos + 1], byteorder='big')
                    data_pos += 1

                    packet_size = self.stream_sensors[packet_id][0]
                    packet_data = data[data_pos:data_pos + packet_size]
                    data_pos += packet_size

                    result.append(
                        int.from_bytes(packet_data, byteorder='big', signed=self.stream_sensors[packet_id][1]))

        return result

    @staticmethod
    def _connect_serial(port, bau_rate, time_out):
        serial_con = serial.Serial(port, baudrate=bau_rate, timeout=time_out)
        if serial_con.isOpen():
            print('Serial port is open, presumably to a roomba...')
        else:
            print('Serial port did NOT open')
        return serial_con

    @staticmethod
    def _adjust_min_max(val, min_val, max_val):

        # integer cast
        if type(val) != int:
            val = int(val)

        if val < min_val:
            val = min_val
        elif val > max_val:
            val = max_val

        return val

    @staticmethod
    def _get_2_bytes(value):
        """ returns two bytes (ints) in high, low order
        whose bits form the input value when interpreted in
        two's complement
        """
        # if positive or zero, it's OK
        if value >= 0:
            eqBitVal = value
        # if it's negative, I think it is this
        else:
            eqBitVal = (1 << 16) + value

        return (eqBitVal >> 8) & 0xFF, eqBitVal & 0xFF

    @staticmethod
    def _get_1_bytes(value):
        """ returns one bytes (int)
        """
        # if positive or zero, it's OK
        if value >= 0:
            eqBitVal = value
        # if it's negative, I think it is this
        else:
            eqBitVal = (1 << 8) + value
        return eqBitVal & 0xFF

    def _send_cmd(self, cmd):
        if type(cmd) == list:  # command list
            self.serial_con.write(bytes(cmd))
        else:  # one command
            self.serial_con.write(bytes([cmd]))