NRF5340 Max throughput

[Branislav]

Hello,

I have a nrf5340dk communicating with nrf52840 dongle connected to a pc with UART baud rate of 2M.

Connection parameters are:

• 7.5ms Conn interval
• 1ms Slave latency
• 247 MTU
• 251 DLE
• 2M PHY

nrf5340dk is configured as nus peripheral.

In the code, there is a high priority thread that is in an infinite loop calling bt_nus_send with a 244 byte buffer and here are the results I get when profiling the packets:


Although, in here it suggest I should be getting a ~1.3 Mbps throughput with 400 ms connection interval, but instead I get this:


I wanted to ask, is there something that needs to be additionally done to get the ~1.3 Mbps throughput or is this the limitation of the hardware, and if someone knows why I get less throughput when I set connection interval to 400 ms.

Additional info:

• NRF Connect SDK: v1.8.0 and v1.9.1 were used, there was no difference between them
• PC is running Windows 10, communicating via Blatann library
• nrf5340's antenna is a few centimeters away from nrf52840 usb dongle

[Vidar Berg]

Hello,

The throughput may also be limited by the Central (PC in this case). I made a test based on the peripheral_uart sample to test the same here and I was able to get around 1000 kbps (also limited by central). This test app starts sending notifications with dummy data as soon as soon as the client enables the notifications. It then it prints the measured throughput out on UART.

Could you try it and see if you get a comparable results? Here is the project I used:

peripheral_uart_throughput_test.zip

My setup:

- Bluetooth low enegery app v3.0.1 in nRF connect for desktop

- nRF52840 Dongle

- nRF5340DK

Result:

Best regards,

Vidar

[Branislav]

Hi Vidar,

Yes, those are the same results I'm getting on my end.
Is there a way to get a better throughput with central, without making a custom firmware for the dongle, or is this that can be done with the current official firwmare?

[Vidar Berg]

Hi,

You mean you get the same result if you use my FW or if you use the nRF connect app? I am not sure if the blatann script is configured to support long MTU and radio packets which will have a significant impact on the throughput.

Thanks,

[Branislav]

The results I get from your app are in the same range as the screenshot I have posted, the troughput is 1110 - 1133 kbps.

And no, blatann doesn't support long mtu packets, my question is is there something that can be done on the side of the dongle to get the rest of the throughput that has been measured when using two dev boards.

And do you maybe know why do those meausrements work well with 400 ms connection interval while in this scenario only 7.5 ms inteval gives the best throughput?

[Vidar Berg]

Sorry, I did not notice the other screenshot. I only saw the one where you got the low throughput @ 400 ms. A likely explanation for this is that the connection event length is too short. The connection event length can be configured when you enable the BLE stack on the dongle.

I increased the event length to 400 ms at line 141 in this pc-ble-driver-py script:

Fullscreen 4010.nus_central.py Download

#
# Copyright (c) 2016 Nordic Semiconductor ASA
# All rights reserved.
#
# Redistribution and use in source and binary forms, with or without modification,
# are permitted provided that the following conditions are met:
#
#   1. Redistributions of source code must retain the above copyright notice, this
#   list of conditions and the following disclaimer.
#
#   2. Redistributions in binary form must reproduce the above copyright notice, this
#   list of conditions and the following disclaimer in the documentation and/or
#   other materials provided with the distribution.
#
#   3. Neither the name of Nordic Semiconductor ASA nor the names of other
#   contributors to this software may be used to endorse or promote products
#   derived from this software without specific prior written permission.
#
#   4. This software must only be used in or with a processor manufactured by Nordic
#   Semiconductor ASA, or in or with a processor manufactured by a third party that
#   is used in combination with a processor manufactured by Nordic Semiconductor.
#
#   5. Any software provided in binary or object form under this license must not be
#   reverse engineered, decompiled, modified and/or disassembled.
#
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
# ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
# WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
# DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR
# ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
# (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
# LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
# ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
# SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
#

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

TARGET_DEV_NAME = "Nordic_UART"
CONNECTIONS = 1
CFG_TAG = 1

global config, BLEDriver, BLEAdvData, BLEEvtID, BLEAdapter, BLEEnableParams, BLEGapTimeoutSrc, BLEUUID, BLEUUIDBase, BLEConfigCommon, BLEConfig, BLEConfigConnGatt, BLEGapScanParams, BLEConfigConnGap, BLEGapConnParams
from pc_ble_driver_py import config
config.__conn_ic_id__ = "NRF52"
# noinspection PyUnresolvedReferences
from pc_ble_driver_py.ble_driver import (
        BLEDriver,
    BLEAdvData,
    BLEEvtID,
    BLEEnableParams,
    BLEGapTimeoutSrc,
    BLEUUID,
    BLEUUIDBase,
    BLEGapScanParams,
    BLEGapConnParams,
    BLEConfigCommon,
    BLEConfig,
    BLEConfigConnGatt,
    BLEConfigConnGap,
)


def init(conn_ic_id):
    # noinspection PyGlobalUndefined
    global config, BLEDriver, BLEAdvData, BLEEvtID, BLEAdapter, BLEEnableParams, BLEGapTimeoutSrc, BLEUUID, BLEUUIDBase, BLEConfigCommon, BLEConfig, BLEConfigConnGatt, BLEGapScanParams, BLEConfigConnGap, BLEGapConnParams
    from pc_ble_driver_py import config

    config.__conn_ic_id__ = conn_ic_id
    # noinspection PyUnresolvedReferences
    from pc_ble_driver_py.ble_driver import (
        BLEDriver,
        BLEAdvData,
        BLEEvtID,
        BLEEnableParams,
        BLEGapTimeoutSrc,
        BLEUUID,
        BLEUUIDBase,
        BLEGapScanParams,
        BLEGapConnParams,
        BLEConfigCommon,
        BLEConfig,
        BLEConfigConnGatt,
        BLEConfigConnGap,
    )

    # noinspection PyUnresolvedReferences
    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 NusCollector(BLEDriverObserver, BLEAdapterObserver):
    
    CUS_BASE_UUID = BLEUUIDBase([
            0x6e, 0x40, 0x00, 0x00, 0xb5, 0xa3, 0xf3, 0x93, 0xe0, 0xa9, 0xe5, 0x0e, 0x24, 0xdc, 0xca, 0x9e
        ])
    CUS_WR_UUID = BLEUUID(0x0002, CUS_BASE_UUID)
    CUS_RD_UUID = BLEUUID(0x0003, CUS_BASE_UUID)
    def __init__(self, adapter):
        super(NusCollector, self).__init__()
        self.first = 1
        self.adapter = adapter
        self.conn_q = Queue()
        self.adapter.observer_register(self)
        self.adapter.driver.observer_register(self)
        self.adapter.default_mtu = 247
        self.nus_base = BLEUUIDBase([
            0x6e, 0x40, 0x00, 0x00, 0xb5, 0xa3, 0xf3, 0x93, 0xe0, 0xa9, 0xe5, 0x0e, 0x24, 0xdc, 0xca, 0x9e
        ], 0x2)
        self.nus_rx = BLEUUID(0x0002, self.nus_base)
        self.nus_tx = BLEUUID(0x0003, self.nus_base)

    def open(self):
        self.adapter.driver.open()
        if config.__conn_ic_id__ == "NRF51":
            self.adapter.driver.ble_enable(
                BLEEnableParams(
                    vs_uuid_count=1,
                    service_changed=0,
                    periph_conn_count=0,
                    central_conn_count=1,
                    central_sec_count=0,
                )
            )
        elif config.__conn_ic_id__ == "NRF52":
            gatt_cfg = BLEConfigConnGatt()
            gatt_cfg.att_mtu = self.adapter.default_mtu
            gatt_cfg.tag = CFG_TAG
            self.adapter.driver.ble_cfg_set(BLEConfig.conn_gatt, gatt_cfg)

            conn_cfg = BLEConfigConnGap()
            conn_cfg.conn_count = 1
            conn_cfg.event_length = 320
            self.adapter.driver.ble_cfg_set(BLEConfig.conn_gap, conn_cfg)

            self.adapter.driver.ble_enable()
            #self.adapter.driver.ble_vs_uuid_add(self.nus_base)
            self.adapter.driver.ble_vs_uuid_add(NusCollector.CUS_BASE_UUID)



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

    def connect_and_discover(self):
        scan_duration = 5
        scan_params = BLEGapScanParams(interval_ms=200, window_ms=150, timeout_s=scan_duration)
        message = "We are connected!\r\n"

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

        try:
            new_conn = self.conn_q.get(timeout=scan_duration)
            self.adapter.service_discovery(new_conn)
            #self.adapter.enable_notification(new_conn, self.nus_tx)
            self.adapter.enable_notification(new_conn, NusCollector.CUS_RD_UUID)
            data = [ord(n) for n in list(message)]
            self.adapter.write_cmd(new_conn, NusCollector.CUS_WR_UUID, data)
            return new_conn
        except Empty:
            print("No device advertising with name {TARGET_DEV_NAME} found.")
            return None

    def on_gattc_evt_exchange_mtu_rsp(self, ble_driver, conn_handle, status, att_mtu):
        print("ATT MTU updated to {}".format(att_mtu))
    
    def on_gap_evt_data_length_update(
        self, ble_driver, conn_handle, data_length_params
    ):
        print("Max rx octets: {}".format(data_length_params.max_rx_octets))
        print("Max tx octets: {}".format(data_length_params.max_tx_octets))
        print("Max rx time: {}".format(data_length_params.max_rx_time_us))
        print("Max tx time: {}".format(data_length_params.max_tx_time_us))

    def on_gatts_evt_exchange_mtu_request(self, ble_driver, conn_handle, client_mtu):
        print("Client requesting to update ATT MTU to {} bytes".format(client_mtu))
    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
    ):
        conn_params = BLEGapConnParams(min_conn_interval_ms=7.5, max_conn_interval_ms=7.5, conn_sup_timeout_ms=4000, slave_latency=0)
        
        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 == TARGET_DEV_NAME:
            self.adapter.connect(peer_addr, conn_params = conn_params, tag=CFG_TAG)

    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))


def main(selected_serial_port):
    print("Serial port used: {}".format(selected_serial_port))
    driver = BLEDriver(
        serial_port=selected_serial_port, auto_flash=False, baud_rate=1000000, log_severity_level="info"
    )

    adapter = BLEAdapter(driver)
    collector = NusCollector(adapter)
    collector.open()
    conn = collector.connect_and_discover()

    while conn is not None:
        time.sleep(100)

    collector.close()


def item_choose(item_list):
    for i, it in enumerate(item_list):
        print("\t{} : {}".format(i, it))
    print(" ")

    while True:
        try:
            choice = int(input("Enter your choice: "))
            if (choice >= 0) and (choice < len(item_list)):
                break
        except Exception:
            pass
        print("\tTry again...")
    return choice


if __name__ == "__main__":
    logging.basicConfig(
        level="DEBUG",
       format="%(asctime)s [%(thread)d/%(threadName)s] %(message)s",
    )
    serial_port = None
    if len(sys.argv) < 2:
        print("Please specify connectivity IC identifier (NRF51, NRF52)")
        exit(1)
    init(sys.argv[1])
    if len(sys.argv) == 3:
        serial_port = sys.argv[2]
    else:
        descs = BLEDriver.enum_serial_ports()
        choices = ["{}: {}".format(d.port, d.serial_number) for d in descs]
        choice = item_choose(choices)
        serial_port = descs[choice].port
    main(serial_port)
    quit()