reader.py

import sys
import asyncio
import pathlib

from bleak import BleakClient
from bleak.uuids import uuid16_dict

uuid16_dict = {v: k for k, v in uuid16_dict.items()}
filename = "ble_data.txt"
start_writing = False

USER_DATA_SERVICE_UUID = "0000{0:x}-0000-1000-8000-00805f9b34fb".format(
    uuid16_dict.get("User Data")  # 0x181C
)

STRING_CHARACTERISTIC_UUID = "0000{0:x}-0000-1000-8000-00805f9b34fb".format(
    uuid16_dict.get("String")  # 0x2A3D
)

last_index = -1
async def main(address: str):
    while True:
        print("Connecting to device...")
        try:
            async with BleakClient(address) as client:
                global start_writing
                start_writing = False
                def coordinates_handler(_, data):
                    global start_writing
                    data_str = data.decode("utf-8") 
                    if data_str == "stop":
                        start_writing = True
                        return
                    print(data_str)
                    if not start_writing:
                        return

                    pathlib.Path("out").mkdir(parents=True, exist_ok=True)
                    with open(f"out/{filename}", "a+") as f:
                        global last_index
                        if (data_str[0] != last_index):
                            f.write(data_str[1:] + "\n")
                            f.close()
                            last_index = data_str[0]
                        

                print(f"Connected: {client.is_connected}")
                try:
                    while client.is_connected:
                        ids_service = (await client.get_services()).get_service(USER_DATA_SERVICE_UUID)
                        coordinates_char = ids_service.get_characteristic(STRING_CHARACTERISTIC_UUID)
                        coordinates_handler(None, await client.read_gatt_char(coordinates_char))
                except Exception as e:
                    print(e)
        except Exception as e:
            print(e)
        
if __name__ == "__main__":
    if len(sys.argv) == 2 or len(sys.argv) == 3:
        filename = sys.argv[2] if len(sys.argv) == 3 else filename
        asyncio.run(main(sys.argv[1]))
    else:
        print("Usage: pipenv run read <address> [<filename>]")