Raspberry Pi low voltage and temperature Python check

check_raspi_throttle.py

#!/usr/bin/env python3
"""Decode Raspberry Pi "vcgencmd throttled" bitmask into text."""

import argparse
import re
import subprocess
import sys

BITMAP = {
    0: "Under-voltage detected",
    1: "Arm frequency capped",
    2: "Currently throttled",
    3: "Soft temperature limit active",
    16: "Under-voltage has occurred",
    17: "Arm frequency capping has occurred",
    18: "Throttling has occurred",
    19: "Soft temperature limit has occurred",
}


def parse_throttled_value(text: str) -> int:
    """Parse a throttled value from vcgencmd output or a raw integer string."""
    s = text.strip()

    # Accept full vcgencmd output like "throttled=0x50000".
    if "=" in s:
        s = s.split("=", 1)[1].strip()

    if re.fullmatch(r"0x[0-9a-fA-F]+", s):
        return int(s, 16)

    if re.fullmatch(r"\d+", s):
        return int(s, 10)

    raise ValueError(f"Could not parse throttled value: {text!r}")


def read_vcgencmd() -> int:
    """Run vcgencmd get_throttled and return decoded integer bitmask."""
    output = subprocess.check_output(["vcgencmd", "get_throttled"], text=True)
    return parse_throttled_value(output)


def main() -> int:
    parser = argparse.ArgumentParser(
        description="Decode Raspberry Pi throttled flags to human-readable text."
    )
    parser.add_argument(
        "value",
        nargs="?",
        help=(
            "Optional throttled value, e.g. 0x50000, 327680, or "
            "'throttled=0x50000'. If omitted, runs vcgencmd get_throttled."
        ),
    )

    args = parser.parse_args()

    value = parse_throttled_value(args.value) if args.value else read_vcgencmd()

    print(f"throttled=0x{value:x}")

    set_known_bits = [bit for bit in sorted(BITMAP) if value & (1 << bit)]

    if not set_known_bits:
        print("No known throttled bits are set.")
    else:
        print("Set throttled bits:")
        for bit in set_known_bits:
            print(f"  bit {bit}: {BITMAP[bit]}")

    unknown_bits = [bit for bit in range(value.bit_length()) if value & (1 << bit) and bit not in BITMAP]
    if unknown_bits:
        print("Unknown set bits: " + ", ".join(str(bit) for bit in unknown_bits))

    return 0


if __name__ == "__main__":
    raise SystemExit(main())