pc-ble-driver-py - Maximum data rate

RE: pc-ble-driver-py - Maximum data rate

Sigurd — Thu, 27 Feb 2020 09:51:24 GMT

There is a significant overhead using serialization, but only 300 bytes/ second is lower than what is expected. There are more reports about pc_ble_driver_py being slow, e.g in this post. We are looking into what is causing this.

RE: pc-ble-driver-py - Maximum data rate

frostp — Fri, 14 Feb 2020 11:41:10 GMT

Hi, apologies for the slow response, I've changed the test to this:

    timeBefore = time.perf_counter()
    bytesSent = 0
    for i in range(100):
        try:
            adapter.write_cmd(conn, bulkDataUuid, bytes(20))
            bytesSent += 20
        except NordicSemiException as error:
            if error.error_code == BLE_ERROR_NO_TX_PACKETS:
                adapter.evt_sync[conn].wait(BLEEvtID.evt_tx_complete)
            else:
                print(str(i) + " failed" + error)

    print("sending %d bytes took %f seconds, %f b/s" % (bytesSent, time.perf_counter() - timeBefore, bytesSent / (time.perf_counter() - timeBefore)))

Is this the sort of thing you meant? It is a little bit faster, about 300 bytes / second on average.

Edit: Just thought I'd add that I can't find a define for BLE_ERROR_NO_TX_PACKETS in the python BLE drivers at all so I just added BLE_ERROR_NO_TX_PACKETS = 12292 in my file.

RE: pc-ble-driver-py - Maximum data rate

Sigurd — Thu, 06 Feb 2020 15:38:02 GMT

The pc-ble-driver-(py) could add some delays to when you get the BLE_EVT_TX_COMPLETE event back.

Try fulling up the packet buffer, until your write command returns BLE_ERROR_NO_TX_PACKETS. See this link.

RE: pc-ble-driver-py - Maximum data rate

frostp — Wed, 05 Feb 2020 17:01:27 GMT

Yep, no problem

devzone.nordicsemi.com/.../Data-Rate-Test.pcapng

RE: pc-ble-driver-py - Maximum data rate

Sigurd — Wed, 05 Feb 2020 16:06:35 GMT

[quote user="frostp"]I checked with the nrf sniffer [/quote]

Can you upload the sniffer log?

RE: pc-ble-driver-py - Maximum data rate

frostp — Wed, 05 Feb 2020 14:41:21 GMT

Ah yes sorry forgot to say, 7.5ms, and I checked with the nrf sniffer that it is definitely is using that interval.

Edit: Just to add more info, I'm using the NRF51 dongle, and LE Secure passkey pairing

RE: pc-ble-driver-py - Maximum data rate

Sigurd — Wed, 05 Feb 2020 14:26:35 GMT

What connection interval are you using for the BLE connection?