esp32 autoflash firmware

#!/usr/bin/env python3

import subprocess
import time
from argparse import ArgumentParser, ArgumentDefaultsHelpFormatter
from pathlib import Path
from threading import Thread


def get_args():
    parser = ArgumentParser(formatter_class=ArgumentDefaultsHelpFormatter)
    parser.add_argument("firmware", help="File for writing to esp32 flash")
    parser.add_argument("-g", "--glob", action="store", default="ttyUSB*", help="Pattern to match port names")
    return parser.parse_args()


def flash(port, firmware):
    """
    Write firmware at offset 0x1000
    """
    cmd = [
        "esptool.py",
        "-p",
        port,
        "-b",
        "921600",
        "write_flash",
        "-z",
        "0x1000",
        firmware,
    ]
    print("Flashing", port)
    try:
        subprocess.run(
            cmd, stderr=subprocess.DEVNULL, stdout=subprocess.DEVNULL, check=True
        )
    except subprocess.CalledProcessError:
        print("Failed to flash device", port)
    else:
        print("Done with", port)


def get_tty():
    return set(Path("/dev").glob(GLOB))


def observer(input_file):
    last_devs = get_tty()
    while True:
        current_devs = get_tty()
        diff = current_devs - last_devs
        last_devs = current_devs
        if diff:
            for port in diff:
                Thread(target=flash, args=(port, input_file)).start()
        time.sleep(1)


if __name__ == "__main__":
    args = get_args()
    GLOB = args.glob

    try:
        observer(args.firmware)
    except KeyboardInterrupt:
        print("\rExit")


"""
esptool.py esp32 \
    -p /dev/ttyUSB0 \
    -b 460800 \
    --before=default_reset \
    --after=hard_reset write_flash \
    --flash_mode dio \
    --flash_freq 40m \
    --flash_size 4MB \
    0x1000 bootloader/bootloader.bin \
    0x10000 micropython.bin \
    0x8000 partition_table/partition-table.bin
"""