Betaflight MSP protocol

MSP protocol overview

MSP (MultiWii Serial Protocol) is the serial request/response protocol used by Betaflight Configurator and external tools to read telemetry, inspect settings, and send configuration commands to the flight controller.

MSP v1 is the original frame format. It is simple and compact, but command IDs are limited to one byte and the payload length is limited to 255 bytes. MSP v2 extends the frame with 16-bit command IDs, larger payload support, flags, and a stronger checksum. Betaflight still supports MSP v1 for compatibility, while newer or larger commands can use MSP v2 framing.

The full list of Betaflight MSP command IDs is maintained in the Betaflight source tree:

• MSP command definitions
• MSP command handlers

As of the current Betaflight master branch, msp_protocol.h defines 167 MSP_* IDs. Of those, 164 are usable command/response IDs; two are reserved IDs and MSP_V2_FRAME is the MSPv2 frame marker rather than a normal command.

MSP command IDs

ID	Command	Usage	Description
1	MSP_API_VERSION	Read	Get API version
2	MSP_FC_VARIANT	Read	Get flight controller variant
3	MSP_FC_VERSION	Read	Get flight controller version
4	MSP_BOARD_INFO	Read	Get board information
5	MSP_BUILD_INFO	Read	Get build information
10	MSP_NAME	Read	Returns user set board name - betaflight
11	MSP_SET_NAME	Write/action	Sets board name - betaflight
32	MSP_BATTERY_CONFIG	Read	Get battery configuration
33	MSP_SET_BATTERY_CONFIG	Write/action	Set battery configuration
34	MSP_MODE_RANGES	Read	Returns all mode ranges
35	MSP_SET_MODE_RANGE	Write/action	Sets a single mode range
36	MSP_FEATURE_CONFIG	Read	Get feature configuration
37	MSP_SET_FEATURE_CONFIG	Write/action	Set feature configuration
38	MSP_BOARD_ALIGNMENT_CONFIG	Read	Get board alignment configuration
39	MSP_SET_BOARD_ALIGNMENT_CONFIG	Write/action	Set board alignment configuration
40	MSP_CURRENT_METER_CONFIG	Read	Get current meter configuration
41	MSP_SET_CURRENT_METER_CONFIG	Write/action	Set current meter configuration
42	MSP_MIXER_CONFIG	Read	Get mixer configuration
43	MSP_SET_MIXER_CONFIG	Write/action	Set mixer configuration
44	MSP_RX_CONFIG	Read	Get RX configuration
45	MSP_SET_RX_CONFIG	Write/action	Set RX configuration
46	MSP_LED_COLORS	Read	Get LED colors
47	MSP_SET_LED_COLORS	Write/action	Set LED colors
48	MSP_LED_STRIP_CONFIG	Read	Get LED strip configuration
49	MSP_SET_LED_STRIP_CONFIG	Write/action	Set LED strip configuration
50	MSP_RSSI_CONFIG	Read	Get RSSI configuration
51	MSP_SET_RSSI_CONFIG	Write/action	Set RSSI configuration
52	MSP_ADJUSTMENT_RANGES	Read	Get adjustment ranges
53	MSP_SET_ADJUSTMENT_RANGE	Write/action	Set adjustment range
54	MSP_CF_SERIAL_CONFIG	Read	Get Cleanflight serial configuration
55	MSP_SET_CF_SERIAL_CONFIG	Write/action	Set Cleanflight serial configuration
56	MSP_VOLTAGE_METER_CONFIG	Read	Get voltage meter configuration
57	MSP_SET_VOLTAGE_METER_CONFIG	Write/action	Set voltage meter configuration
58	MSP_SONAR_ALTITUDE	Read	Get sonar altitude [cm]
59	MSP_PID_CONTROLLER	Read	Get PID controller
60	MSP_SET_PID_CONTROLLER	Write/action	Set PID controller
61	MSP_ARMING_CONFIG	Read	Get arming configuration
62	MSP_SET_ARMING_CONFIG	Write/action	Set arming configuration
64	MSP_RX_MAP	Read	Get RX map (also returns number of channels total)
65	MSP_SET_RX_MAP	Write/action	Set RX map, numchannels to set comes from MSP_RX_MAP
68	MSP_REBOOT	Write/action	Reboot settings
70	MSP_DATAFLASH_SUMMARY	Read	Get description of dataflash chip
71	MSP_DATAFLASH_READ	Read	Get content of dataflash chip
72	MSP_DATAFLASH_ERASE	Write/action	Erase dataflash chip
75	MSP_FAILSAFE_CONFIG	Read	Get failsafe settings
76	MSP_SET_FAILSAFE_CONFIG	Write/action	Set failsafe settings
77	MSP_RXFAIL_CONFIG	Read	Get RX failsafe settings
78	MSP_SET_RXFAIL_CONFIG	Write/action	Set RX failsafe settings
79	MSP_SDCARD_SUMMARY	Read	Get SD card state
80	MSP_BLACKBOX_CONFIG	Read	Get blackbox settings
81	MSP_SET_BLACKBOX_CONFIG	Write/action	Set blackbox settings
82	MSP_TRANSPONDER_CONFIG	Read	Get transponder settings
83	MSP_SET_TRANSPONDER_CONFIG	Write/action	Set transponder settings
84	MSP_OSD_CONFIG	Read	Get OSD settings
85	MSP_SET_OSD_CONFIG	Write/action	Set OSD settings
86	MSP_OSD_CHAR_READ	Read	Get OSD characters
87	MSP_OSD_CHAR_WRITE	Write/action	Set OSD characters
88	MSP_VTX_CONFIG	Read	Get VTX settings
89	MSP_SET_VTX_CONFIG	Write/action	Set VTX settings
90	MSP_ADVANCED_CONFIG	Read	Get advanced configuration
91	MSP_SET_ADVANCED_CONFIG	Write/action	Set advanced configuration
92	MSP_FILTER_CONFIG	Read	Get filter configuration
93	MSP_SET_FILTER_CONFIG	Write/action	Set filter configuration
94	MSP_PID_ADVANCED	Read	Get advanced PID settings
95	MSP_SET_PID_ADVANCED	Write/action	Set advanced PID settings
96	MSP_SENSOR_CONFIG	Read	Get sensor configuration
97	MSP_SET_SENSOR_CONFIG	Write/action	Set sensor configuration
98	MSP_CAMERA_CONTROL	Read/write	Camera control
99	MSP_SET_ARMING_DISABLED	Write/action	Enable/disable arming
101	MSP_STATUS	Read	Cycletime & errors_count & sensor present & box activation & current setting number
102	MSP_RAW_IMU	Read	9 DOF
103	MSP_SERVO	Read	Servos
104	MSP_MOTOR	Read	Motors
105	MSP_RC	Read	RC channels and more
106	MSP_RAW_GPS	Read	Fix, numsat, lat, lon, alt, speed, ground course
107	MSP_COMP_GPS	Read	Distance home, direction home
108	MSP_ATTITUDE	Read	2 angles 1 heading
109	MSP_ALTITUDE	Read	Altitude, variometer
110	MSP_ANALOG	Read	Vbat, powermetersum, rssi if available on RX
111	MSP_RC_TUNING	Read	RC rate, rc expo, rollpitch rate, yaw rate, dyn throttle PID
112	MSP_PID	Read	P I D coeff (9 are used currently)
116	MSP_BOXNAMES	Read	The aux switch names
117	MSP_PIDNAMES	Read	The PID names
118	MSP_WP	Read	Get a WP, WP# is in the payload, returns (WP#, lat, lon, alt, flags) WP#0-home, WP#16-poshold
119	MSP_BOXIDS	Read	Get the permanent IDs associated to BOXes
120	MSP_SERVO_CONFIGURATIONS	Read	All servo configurations
121	MSP_NAV_STATUS	Read	Returns navigation status
122	MSP_NAV_CONFIG	Read	Returns navigation parameters
124	MSP_MOTOR_3D_CONFIG	Read	Settings needed for reversible ESCs
125	MSP_RC_DEADBAND	Read	Deadbands for yaw alt pitch roll
126	MSP_SENSOR_ALIGNMENT	Read	Orientation of acc,gyro,mag
127	MSP_LED_STRIP_MODECOLOR	Read	Get LED strip mode_color settings
128	MSP_VOLTAGE_METERS	Read	Voltage (per meter)
129	MSP_CURRENT_METERS	Read	Amperage (per meter)
130	MSP_BATTERY_STATE	Read	Connected/Disconnected, Voltage, Current Used
131	MSP_MOTOR_CONFIG	Read	Motor configuration (min/max throttle, etc)
132	MSP_GPS_CONFIG	Read	GPS configuration
133	MSP_COMPASS_CONFIG	Read	Compass configuration
134	MSP_ESC_SENSOR_DATA	Read	Extra ESC data from 32-Bit ESCs (Temperature, RPM)
135	MSP_GPS_RESCUE	Read	GPS Rescue angle, returnAltitude, descentDistance, groundSpeed, sanityChecks and minSats
136	MSP_GPS_RESCUE_PIDS	Read	GPS Rescue throttleP and velocity PIDS + yaw P
137	MSP_VTXTABLE_BAND	Read	VTX table band/channel data
138	MSP_VTXTABLE_POWERLEVEL	Read	VTX table powerLevel data
139	MSP_MOTOR_TELEMETRY	Read	Per-motor telemetry data (RPM, packet stats, ESC temp, etc.)
140	MSP_SIMPLIFIED_TUNING	Read	Get simplified tuning values and enabled state
141	MSP_SET_SIMPLIFIED_TUNING	Write/action	Set simplified tuning positions and apply calculated tuning
142	MSP_CALCULATE_SIMPLIFIED_PID	Read	Calculate PID values based on sliders without saving
143	MSP_CALCULATE_SIMPLIFIED_GYRO	Read	Calculate gyro filter values based on sliders without saving
144	MSP_CALCULATE_SIMPLIFIED_DTERM	Read	Calculate D term filter values based on sliders without saving
145	MSP_VALIDATE_SIMPLIFIED_TUNING	Read	Returns array of true/false showing which simplified tuning groups match values
150	MSP_STATUS_EX	Read	Cycletime, errors_count, CPU load, sensor present etc
160	MSP_UID	Read	Unique device ID
164	MSP_GPSSVINFO	Read	Get Signal Strength (only U-Blox)
166	MSP_GPSSTATISTICS	Read	Get GPS debugging data
167	MSP_ATTITUDE_QUATERNION	Read	Orientation quaternion components (w, x, y, z)
180	MSP_OSD_VIDEO_CONFIG	Read	Get OSD video settings
181	MSP_SET_OSD_VIDEO_CONFIG	Write/action	Set OSD video settings
182	MSP_DISPLAYPORT	Read	External OSD displayport mode
183	MSP_COPY_PROFILE	Write/action	Copy settings between profiles
184	MSP_BEEPER_CONFIG	Read	Get beeper configuration
185	MSP_SET_BEEPER_CONFIG	Write/action	Set beeper configuration
186	MSP_SET_TX_INFO	Write/action	Set runtime information from TX lua scripts
187	MSP_TX_INFO	Read	Get runtime information for TX lua scripts
188	MSP_SET_OSD_CANVAS	Write/action	Set OSD canvas size COLSxROWS
189	MSP_OSD_CANVAS	Read	Get OSD canvas size COLSxROWS
200	MSP_SET_RAW_RC	Write/action	8 rc chan
201	MSP_SET_RAW_GPS	Write/action	Fix, numsat, lat, lon, alt, speed
202	MSP_SET_PID	Write/action	P I D coeff (9 are used currently)
204	MSP_SET_RC_TUNING	Write/action	RC rate, rc expo, rollpitch rate, yaw rate, dyn throttle PID, yaw expo
205	MSP_ACC_CALIBRATION	Write/action	No param - calibrate accelerometer
206	MSP_MAG_CALIBRATION	Write/action	No param - calibrate magnetometer
208	MSP_RESET_CONF	Write/action	No param - reset settings
209	MSP_SET_WP	Write/action	Sets a given WP (WP#,lat, lon, alt, flags)
210	MSP_SELECT_SETTING	Write/action	Select setting number (0-2)
211	MSP_SET_HEADING	Write/action	Define a new heading hold direction
212	MSP_SET_SERVO_CONFIGURATION	Write/action	Servo settings
214	MSP_SET_MOTOR	Write/action	PropBalance function
215	MSP_SET_NAV_CONFIG	Write/action	Sets nav config parameters
217	MSP_SET_MOTOR_3D_CONFIG	Write/action	Settings needed for reversible ESCs
218	MSP_SET_RC_DEADBAND	Write/action	Deadbands for yaw alt pitch roll
219	MSP_SET_RESET_CURR_PID	Write/action	Reset current PID profile to defaults
220	MSP_SET_SENSOR_ALIGNMENT	Write/action	Set the orientation of acc,gyro,mag
221	MSP_SET_LED_STRIP_MODECOLOR	Write/action	Set LED strip mode_color settings
222	MSP_SET_MOTOR_CONFIG	Write/action	Motor configuration (min/max throttle, etc)
223	MSP_SET_GPS_CONFIG	Write/action	GPS configuration
224	MSP_SET_COMPASS_CONFIG	Write/action	Compass configuration
225	MSP_SET_GPS_RESCUE	Write/action	Set GPS Rescue parameters
226	MSP_SET_GPS_RESCUE_PIDS	Write/action	Set GPS Rescue PID values
227	MSP_SET_VTXTABLE_BAND	Write/action	Set vtxTable band/channel data
228	MSP_SET_VTXTABLE_POWERLEVEL	Write/action	Set vtxTable powerLevel data
230	MSP_MULTIPLE_MSP	Read	Request multiple MSPs in one request
238	MSP_MODE_RANGES_EXTRA	Read	Extra mode range data
239	MSP_SET_ACC_TRIM	Write/action	Set acc angle trim values
240	MSP_ACC_TRIM	Read	Get acc angle trim values
241	MSP_SERVO_MIX_RULES	Read	Get servo mixer configuration
242	MSP_SET_SERVO_MIX_RULE	Write/action	Set servo mixer configuration
245	MSP_SET_PASSTHROUGH	Write/action	Set passthrough to peripherals
246	MSP_SET_RTC	Write/action	Set the RTC clock
247	MSP_RTC	Read	Get the RTC clock
248	MSP_SET_BOARD_INFO	Write/action	Set the board information
249	MSP_SET_SIGNATURE	Write/action	Set the signature of the board and serial number
250	MSP_EEPROM_WRITE	Write/action	Write settings to EEPROM
251	MSP_RESERVE_1	Reserved	reserved for system usage
252	MSP_RESERVE_2	Reserved	reserved for system usage
253	MSP_DEBUGMSG	Read	debug string buffer
254	MSP_DEBUG	Read	debug1,debug2,debug3,debug4
255	MSP_V2_FRAME	Frame marker	MSPv2 payload indicator

Config betaflight uart port for msp usage

Demo: python msp

MSP_STATUS

MSP_STATUS (101) is a read-only status snapshot. Send it with an empty payload to get the controller loop timing, bus error count, detected sensors, active flight-mode flags, and the selected PID/profile slot. Multi-byte values are returned little-endian.

Offset	Size	Field	Meaning
0	uint16	cycleTime	Main control-loop time in microseconds. Lower values mean the loop is running faster.
2	uint16	i2cErrorCounter	Number of I2C bus errors detected since boot. This should normally stay at 0.
4	uint16	sensorStatus	Bit mask of sensors detected by the firmware. Common bits are accelerometer, barometer, magnetometer, GPS, sonar, and optical flow.
6	uint32	flightModeFlags	Bit mask of currently active BOX/flight modes, such as ARM, ANGLE, HORIZON, BEEPER, GPS Rescue, and other modes configured in Betaflight.
10	uint8	profile	Active PID/profile index reported by the firmware.

Use MSP_STATUS_EX (150) when you also need CPU load, rate profile, and arming-disable reasons. The demo below requests MSP_STATUS_EX so it can print whether the flight controller is armable and why arming may be blocked.

flightModeFlags is a 32-bit mask. Test a mode with flightModeFlags & (1 << bit).

Bit	Mask	Mode
0	0x00000001	ARM
1	0x00000002	ANGLE
2	0x00000004	HORIZON
3	0x00000008	MAG
4	0x00000010	ALTHOLD
5	0x00000020	HEADFREE
6	0x00000040	CHIRP
7	0x00000080	PASSTHRU
8	0x00000100	FAILSAFE
9	0x00000200	POSHOLD
10	0x00000400	GPSRESCUE
11	0x00000800	AUTOPILOT
12	0x00001000	ANTIGRAVITY
13	0x00002000	HEADADJ
14	0x00004000	CAMSTAB
15	0x00008000	BEEPERON
16	0x00010000	LEDLOW
17	0x00020000	CALIB
18	0x00040000	OSD
19	0x00080000	TELEMETRY
20	0x00100000	SERVO1
21	0x00200000	SERVO2
22	0x00400000	SERVO3
23	0x00800000	BLACKBOX
24	0x01000000	AIRMODE
25	0x02000000	3D
26	0x04000000	FPVANGLEMIX
27	0x08000000	BLACKBOXERASE
28	0x10000000	CAMERA1
29	0x20000000	CAMERA2
30	0x40000000	CAMERA3
31	0x80000000	CRASHFLIP

MSP get status

#!/usr/bin/env python3

from __future__ import annotations

import argparse
import json
import struct
import time


DEFAULT_DEVICE = "/dev/ttyUSB0"
DEFAULT_BAUDRATE = 115200
MSP_STATUS_EX = 150

ARMING_DISABLE_FLAGS = {
    0: "NO_GYRO",
    1: "FAILSAFE",
    2: "RX_FAILSAFE",
    3: "NOT_DISARMED",
    4: "BOXFAILSAFE",
    5: "RUNAWAY_TAKEOFF",
    6: "CRASH_DETECTED",
    7: "THROTTLE",
    8: "ANGLE",
    9: "BOOT_GRACE_TIME",
    10: "NOPREARM",
    11: "LOAD",
    12: "CALIBRATING",
    13: "CLI",
    14: "CMS_MENU",
    15: "BST",
    16: "MSP",
    17: "PARALYZE",
    18: "GPS",
    19: "RESCUE_SW",
    20: "RPMFILTER",
    21: "REBOOT_REQUIRED",
    22: "DSHOT_BITBANG",
    23: "ACC_CALIBRATION",
    24: "MOTOR_PROTOCOL",
    25: "ARMING_DISABLED_ARM_SWITCH",
    26: "ALTITUDE",
    27: "POSITION",
    28: "ARM_SWITCH",
}


def msp_v1_request(command: int, payload: bytes = b"") -> bytes:
    size = len(payload)
    checksum = size ^ command
    for byte in payload:
        checksum ^= byte
    return b"$M<" + bytes([size, command]) + payload + bytes([checksum])


def crc8_dvb_s2(data: bytes) -> int:
    crc = 0
    for byte in data:
        crc ^= byte
        for _ in range(8):
            if crc & 0x80:
                crc = ((crc << 1) ^ 0xD5) & 0xFF
            else:
                crc = (crc << 1) & 0xFF
    return crc


def msp_v2_request(command: int, payload: bytes = b"") -> bytes:
    flags = 0
    body = (
        bytes([flags])
        + command.to_bytes(2, "little")
        + len(payload).to_bytes(2, "little")
        + payload
    )
    return b"$X<" + body + bytes([crc8_dvb_s2(body)])


def read_exact(serial_port, size: int, timeout: float) -> bytes:
    serial_port.timeout = timeout
    data = serial_port.read(size)
    if len(data) != size:
        raise TimeoutError(f"Timeout while reading {size} serial bytes")
    return data


def read_msp_response(serial_port, timeout: float) -> tuple[int, bytes]:
    deadline = time.monotonic() + timeout

    while time.monotonic() < deadline:
        remaining = max(0.001, deadline - time.monotonic())
        if read_exact(serial_port, 1, remaining) != b"$":
            continue
        protocol = read_exact(serial_port, 1, remaining)

        if protocol == b"M":
            return read_msp_v1_response_after_header(serial_port, deadline)
        if protocol == b"X":
            return read_msp_v2_response_after_header(serial_port, deadline)

    raise TimeoutError("No MSP response")


def read_msp_v1_response_after_header(serial_port, deadline: float) -> tuple[int, bytes]:
    remaining = max(0.001, deadline - time.monotonic())
    direction = read_exact(serial_port, 1, remaining)
    if direction not in (b">", b"!"):
        raise ValueError(f"Invalid MSP v1 direction: {direction!r}")

    size = read_exact(serial_port, 1, remaining)[0]
    command = read_exact(serial_port, 1, remaining)[0]
    payload = read_exact(serial_port, size, remaining)
    received_checksum = read_exact(serial_port, 1, remaining)[0]

    checksum = size ^ command
    for byte in payload:
        checksum ^= byte
    if checksum != received_checksum:
        raise ValueError(
            f"Bad MSP v1 checksum: got 0x{received_checksum:02x}, "
            f"expected 0x{checksum:02x}"
        )
    if direction == b"!":
        raise RuntimeError(f"MSP error response for command {command}")

    return command, payload


def read_msp_v2_response_after_header(serial_port, deadline: float) -> tuple[int, bytes]:
    remaining = max(0.001, deadline - time.monotonic())
    direction = read_exact(serial_port, 1, remaining)
    if direction not in (b">", b"!"):
        raise ValueError(f"Invalid MSP v2 direction: {direction!r}")

    flags = read_exact(serial_port, 1, remaining)
    command_bytes = read_exact(serial_port, 2, remaining)
    size_bytes = read_exact(serial_port, 2, remaining)
    size = int.from_bytes(size_bytes, "little")
    payload = read_exact(serial_port, size, remaining)
    received_checksum = read_exact(serial_port, 1, remaining)[0]

    checksum_data = flags + command_bytes + size_bytes + payload
    checksum = crc8_dvb_s2(checksum_data)
    if checksum != received_checksum:
        raise ValueError(
            f"Bad MSP v2 checksum: got 0x{received_checksum:02x}, "
            f"expected 0x{checksum:02x}"
        )

    command = int.from_bytes(command_bytes, "little")
    if direction == b"!":
        raise RuntimeError(f"MSP error response for command {command}")

    return command, payload


def request_msp(
    serial_port,
    command: int,
    timeout: float,
    version: int = 1,
) -> bytes:
    if version == 1:
        request = msp_v1_request(command)
    elif version == 2:
        request = msp_v2_request(command)
    else:
        raise ValueError(f"Unsupported MSP version: {version}")

    serial_port.write(request)
    serial_port.flush()

    while True:
        response_command, payload = read_msp_response(serial_port, timeout)
        if response_command == command:
            return payload


def decode_arming_mask(mask: int) -> list[str]:
    return [
        name
        for bit, name in ARMING_DISABLE_FLAGS.items()
        if mask & (1 << bit)
    ]


def parse_status_ex(payload: bytes) -> dict[str, object]:
    if len(payload) < 16:
        raise ValueError(f"MSP_STATUS_EX payload too short: {len(payload)} bytes")

    cycle_time_us = struct.unpack_from("<H", payload, 0)[0]
    i2c_errors = struct.unpack_from("<H", payload, 2)[0]
    sensors_mask = struct.unpack_from("<H", payload, 4)[0]
    box_mode_flags = struct.unpack_from("<I", payload, 6)[0]
    pid_profile = payload[10]
    cpu_load = struct.unpack_from("<H", payload, 11)[0]
    pid_profile_count = payload[13]
    rate_profile = payload[14]
    flight_mode_byte_count = payload[15]
    arming_offset = 16 + flight_mode_byte_count

    if len(payload) < arming_offset + 5:
        raise ValueError(
            f"Cannot decode arming flags. payload_len={len(payload)}, "
            f"flight_mode_byte_count={flight_mode_byte_count}"
        )

    arming_disable_flag_count = payload[arming_offset]
    arming_disable_mask = struct.unpack_from("<I", payload, arming_offset + 1)[0]
    arming_disable_flags = decode_arming_mask(arming_disable_mask)

    return {
        "cycle_time_us": cycle_time_us,
        "i2c_errors": i2c_errors,
        "sensors_mask": sensors_mask,
        "sensors_mask_hex": f"0x{sensors_mask:04x}",
        "box_mode_flags": box_mode_flags,
        "box_mode_flags_hex": f"0x{box_mode_flags:08x}",
        "pid_profile": pid_profile,
        "pid_profile_count": pid_profile_count,
        "rate_profile": rate_profile,
        "cpu_load_raw": cpu_load,
        "flight_mode_byte_count": flight_mode_byte_count,
        "arming_disable_flag_count": arming_disable_flag_count,
        "arming_disable_mask": arming_disable_mask,
        "arming_disable_mask_hex": f"0x{arming_disable_mask:08x}",
        "arming_disable_flags": arming_disable_flags,
        "arming_disabled": bool(arming_disable_flags),
        "armable": not arming_disable_flags,
        "calibrating": "CALIBRATING" in arming_disable_flags,
        "failsafe": "FAILSAFE" in arming_disable_flags
        or "RX_FAILSAFE" in arming_disable_flags,
    }


def parse_args() -> argparse.Namespace:
    parser = argparse.ArgumentParser(
        description="Read Betaflight MSP status telemetry from a serial device."
    )
    parser.add_argument("--device", default=DEFAULT_DEVICE)
    parser.add_argument("--baudrate", default=DEFAULT_BAUDRATE, type=int)
    parser.add_argument("--rate-hz", default=2.0, type=float)
    parser.add_argument("--timeout", default=0.5, type=float)
    parser.add_argument("--count", default=0, type=int, help="0 means run forever")
    parser.add_argument("--msp-version", default=1, choices=(1, 2), type=int)
    return parser.parse_args()


def main() -> None:
    import serial

    args = parse_args()
    interval_s = 1.0 / args.rate_hz if args.rate_hz > 0 else 0.0

    with serial.Serial(
        port=args.device,
        baudrate=args.baudrate,
        timeout=0,
        write_timeout=1,
    ) as serial_port:
        reads = 0
        while args.count <= 0 or reads < args.count:
            started = time.monotonic()
            payload = request_msp(
                serial_port,
                MSP_STATUS_EX,
                args.timeout,
                version=args.msp_version,
            )
            telemetry = parse_status_ex(payload)
            telemetry["timestamp_s"] = time.time()
            print(json.dumps(telemetry, indent=2, sort_keys=True), flush=True)

            reads += 1

            if interval_s:
                elapsed = time.monotonic() - started
                time.sleep(max(0.0, interval_s - elapsed))


if __name__ == "__main__":
    main()