# DJI FCC Patch Script for Windows
#
# This script sends a "magic packet" to a DJI controller
# to enable FCC mode, which can increase the drone's signal range.
#
# Credits:
# - Based on the Android app by Mathieu Broillet: https://github.com/M4TH1EU/DJI-FCC-HACK
# - Original research by @galbb on MavicPilots.com
#
# HOW TO USE:
# 1. Install Python from the Microsoft Store or python.org.
# 2. Install the pyserial library by opening a Command Prompt or PowerShell and running:
#    pip install pyserial
# 3. Turn on your drone and controller, and wait for them to connect.
# 4. Connect your PC to the bottom USB port of the controller.
# 5. Run this script.
# 6. If successful, disconnect the PC and connect your phone to the top USB port of the controller.
#
# DISCLAIMER: Use at your own risk. This script modifies your device's operation.
# The authors are not responsible for any damage or legal issues that may arise.

import serial
import serial.tools.list_ports
import time

# DJI Controller USB identifiers
VENDOR_ID = 11427
PRODUCT_ID = 4128

# The "magic bytes" that enable FCC mode
# (from ch.mathieubroillet.djiffchack.Constants.kt)
BYTES_1 = bytes([85, 13, 4, 33, 42, 31, 0, 0, 0, 0, 1, -122 & 0xFF, 32])
BYTES_2 = bytes([85, 24, 4, 32, 2, 9, 0, 0, 64, 9, 39, 0, 2, 72, 0, -1 & 0xFF, -1 & 0xFF, 2, 0, 0, 0, 0, -127 & 0xFF, 31])

def find_dji_controller():
    """Finds the COM port of the connected DJI controller."""
    ports = serial.tools.list_ports.comports()
    for port in ports:
        if port.vid == VENDOR_ID and port.pid == PRODUCT_ID:
            print(f"Found DJI Controller at {port.device}")
            return port.device
    return None

def send_patch(com_port):
    """Opens the serial port and sends the patch bytes."""
    try:
        with serial.Serial(com_port, baudrate=19200, bytesize=8, parity='N', stopbits=1, timeout=1) as ser:
            print("Sending patch...")

            # Send first byte array
            ser.write(BYTES_1)
            print(f"Sent {len(BYTES_1)} bytes (Packet 1).")
            time.sleep(0.1) # Small delay between writes

            # Send second byte array
            ser.write(BYTES_2)
            print(f"Sent {len(BYTES_2)} bytes (Packet 2).")

            print("\nPatch sent successfully!")
            print("You can now disconnect the controller from your PC.")
            return True
    except serial.SerialException as e:
        print(f"Error: Could not open or write to serial port {com_port}.")
        print(f"Details: {e}")
        print("\nPlease ensure the controller is properly connected and no other software is using the COM port.")
        return False

if __name__ == "__main__":
    print("--- DJI FCC Patch Script ---")
    print("Searching for DJI Controller...")

    controller_port = find_dji_controller()

    if controller_port:
        send_patch(controller_port)
    else:
        print("\nDJI Controller not found.")
        print("Please make sure:")
        print("1. The controller is turned on and connected to the drone.")
        print("2. Your PC is connected to the BOTTOM USB port of the controller.")
        print("3. The necessary USB drivers are installed.")

    print("\nPress Enter to exit.")
    input()