Handling 128-bit UUIDs with Python pc_ble_driver

RE: Handling 128-bit UUIDs with Python pc_ble_driver

Kampino — Wed, 31 Aug 2022 09:03:22 GMT

thanks for your response! I will change it :)

RE: Handling 128-bit UUIDs with Python pc_ble_driver

Hung Bui — Wed, 31 Aug 2022 08:12:02 GMT

Hi Daniel,

Is it possible to change the UUID of the characteristic and service in your application ?

If you are freely to change them I would suggest to follow what we did with the NUS example to have the same UUID base for the characteristic and the service, the only difference is the offset at byte 3rd and 4th.

If it's not possible to change the UUIDs, then what you need to do is to define 3 different UUID base , and each of them would have byte 3rd and 4rd set to 0. In your case the 3rd and 4rd bytes are also 0 so you don't need to do anything.

For example you can define this:
self.your_base1 = BLEUUIDBase([
0x04, 0x06, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xB0, 0xA7, 0x74, 0x4C
])

self.your_base2 = BLEUUIDBase([
0x05, 0x06, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xB0, 0xA7, 0x74, 0x4C
])

self.adapter.driver.ble_vs_uuid_add(self.your_base1)

self.adapter.driver.ble_vs_uuid_add(self.your_base2)

Then you can call:

self.your_first_char = BLEUUID(0x0000, self.your_base1)
self.your_second_char = BLEUUID(0x0000, self.your_base2)

After that you can use your_first_char and your_second_char the same as what we did with the nus_rx and nus_tx.

In short the BLEUUID() is the combination of the 3rd and 4th bytes and the base_uuid.

RE: Handling 128-bit UUIDs with Python pc_ble_driver

Kampino — Tue, 30 Aug 2022 09:38:30 GMT

Hi,

yes, I have tried it and everything is okay. But I don´t know how to use this for my problem.
The NUS example uses the following base UUID

0x4C, 0x74, 0xA7, 0xB0, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x05, 0x01

And the BLEUUID class is generating the following UUIDs based on a base UUID and an offset

6E400002-B5A3-F393-E0A9-E50E24DCCA9E
6E400003-B5A3-F393-E0A9-E50E24DCCA9E

But my UUID is entirely different. The UUID for the service is

0x01, 0x05, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xB0, 0xA7, 0x74, 0x4C

and for each characteristic it is

0x04, 0x06, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xB0, 0xA7, 0x74, 0x4C
0x05, 0x06, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xB0, 0xA7, 0x74, 0x4C

Can I handle this with an offset too? So I have to add

0x03, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00

as an offset?

What is a good way to insert the correct UUIDs in this Python script?

RE: Handling 128-bit UUIDs with Python pc_ble_driver

Hung Bui — Fri, 26 Aug 2022 12:28:43 GMT

Hi,

Have you tried to test with the example from Vidar ?

I'm not sure what the exception is about, but you may want to give the whole log so that I can find more information.

RE: Handling 128-bit UUIDs with Python pc_ble_driver

Kampino — Fri, 26 Aug 2022 11:19:39 GMT

Hi,

I have changed the code to the following:

import sys
import time
import logging
from queue import Queue, Empty
from pc_ble_driver_py.observers import *

global config, BLEDriver, BLEAdvData, BLEEvtID, BLEAdapter, BLEEnableParams, BLEGapTimeoutSrc, BLEUUID, BLEUUIDBase, BLEConfigCommon, BLEConfig, BLEConfigConnGatt, BLEGapScanParams
from pc_ble_driver_py import config

config.__conn_ic_id__ = "NRF52"

from pc_ble_driver_py.ble_driver import (
	BLEDriver,
	BLEAdvData,
	BLEEvtID,
	BLEEnableParams,
	BLEGapTimeoutSrc,
	BLEUUID,
	BLEUUIDBase,
	BLEGapScanParams,
	BLEConfigCommon,
	BLEConfig,
	BLEConfigConnGatt,
)

from pc_ble_driver_py.ble_adapter import BLEAdapter

global nrf_sd_ble_api_ver
nrf_sd_ble_api_ver = config.sd_api_ver_get()

class OTA(BLEDriverObserver, BLEAdapterObserver):
    OTA_BASE_UUID       = BLEUUIDBase(
        [0x4C, 0x74, 0xA7, 0xB0, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x05, 0x01],
        0x02
    )
    OTA_Control_UUID    = BLEUUIDBase(
        [0x4C, 0x74, 0xA7, 0xB0, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x06, 0x04],
        0x02
    )
    OTA_Data_UUID       = BLEUUIDBase(
        [0x4C, 0x74, 0xA7, 0xB0, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x06, 0x05], 
        0x02
    )

    def __init__(self, Adapter):
        super(OTA, self).__init__()
        self.adapter = Adapter
        self.conn_q = Queue()
        self.adapter.observer_register(self)
        self.adapter.driver.observer_register(self)
        self.adapter.default_mtu = 250

    def open(self):
        self.adapter.driver.open()
        gatt_cfg = BLEConfigConnGatt()
        gatt_cfg.att_mtu = self.adapter.default_mtu
        gatt_cfg.tag = 1
        self.adapter.driver.ble_cfg_set(BLEConfig.conn_gatt, gatt_cfg)
        self.adapter.driver.ble_enable()
        self.adapter.driver.ble_vs_uuid_add(OTA.OTA_BASE_UUID)
        self.adapter.driver.ble_vs_uuid_add(OTA.OTA_Control_UUID)
        self.adapter.driver.ble_vs_uuid_add(OTA.OTA_Data_UUID)

    def close(self):
        self.adapter.driver.close()

    def connect_and_discover(self):
        scan_duration = 5
        params = BLEGapScanParams(interval_ms = 200, window_ms = 150, timeout_s = scan_duration)

        self.adapter.driver.ble_gap_scan_start(scan_params = params)

        try:
            new_conn = self.conn_q.get(timeout = scan_duration)
            self.adapter.service_discovery(new_conn)

            return new_conn
        except Empty:
            print("No advertising with name 'jerry3' found.")

            return None

    def on_gap_evt_connected(self, ble_driver, conn_handle, peer_addr, role, conn_params):
        print("New connection: {}".format(conn_handle))
        self.conn_q.put(conn_handle)

    def on_gap_evt_disconnected(self, ble_driver, conn_handle, reason):
        print("Disconnected: {} {}".format(conn_handle, reason))

    def on_gap_evt_adv_report(self, ble_driver, conn_handle, peer_addr, rssi, adv_type, adv_data):
        if(BLEAdvData.Types.complete_local_name in adv_data.records):
            dev_name_list = adv_data.records[BLEAdvData.Types.complete_local_name]
        elif(BLEAdvData.Types.short_local_name in adv_data.records):
            dev_name_list = adv_data.records[BLEAdvData.Types.short_local_name]
        else:
            return

        dev_name = "".join(chr(e) for e in dev_name_list)
        address_string = "".join("{0:02X}".format(b) for b in peer_addr.addr)
        print("Received advertisment report, address: 0x{}, device_name: {}".format(address_string, dev_name))

        if(dev_name == "jerry3"):
            self.adapter.connect(peer_addr, tag = 1)

    def on_notification(self, ble_adapter, conn_handle, uuid, data):
        if(len(data) > 32):
            data = "({}...)".format(data[0:10])
        print("Connection: {}, {} = {}".format(conn_handle, uuid, data))

if(__name__ == "__main__"):
    logging.basicConfig(level = "DEBUG", format = "%(asctime)s [%(thread)d/%(threadName)s] %(message)s")

    Driver = BLEDriver(serial_port = "COM9", auto_flash = False, baud_rate = 1000000, log_severity_level = "info")
    Adapter = BLEAdapter(Driver)
    OTA_Handler = OTA(Adapter)
    OTA_Handler.open()
    Connection = OTA_Handler.connect_and_discover()

    if(Connection is not None):
        while True:
            data = [1]
            Adapter.write_cmd(Connection, OTA.OTA_Control_UUID, data)

    OTA_Handler.close()
    quit()

The application throws an exception with the message

"assert isinstance(uuid, BLEUUID), "Invalid argument type" AssertionError: Invalid argument type"

Where does the error come from?

RE: Handling 128-bit UUIDs with Python pc_ble_driver

Hung Bui — Thu, 25 Aug 2022 11:13:07 GMT

Hi Daniel,

You can have a look at this example from our coworker Vidar:
Adding custome characterstics using pc-ble-driver-py

It's demonstrating a NUS central on PC and you can test it with a ble_app_uart example that is a NUS server/peripheral.