Regarding BLE data transfer speed

RE: Regarding BLE data transfer speed

haakonsh — Wed, 04 Mar 2020 08:22:10 GMT

The connection intervals are still invalid, I recommend a minimum value of 6 (7.5ms) and a maximum value of 24(30ms).

And we still need the logs.

RE: Regarding BLE data transfer speed

Zero.cool — Tue, 03 Mar 2020 02:47:13 GMT

Hi haakonsh,

Thank you for response.

I try to do setup as mentioned and provide logs.

Also I got my settings which are as below set in code.

BLE_GAP_DATA_LENGTH :- 251
PHY - LE 2

MAX_CONN_INTERVAL 5; //in 1.25 ms units.

MIN_CONN_INTERVAL 7.5; //in 1.25 ms units.(Changed as suggested , but no improvements)

GATT_MAX_MTU_SIZE 247,

Provide your view on settings.

Thanks,

RE: Regarding BLE data transfer speed

haakonsh — Mon, 02 Mar 2020 14:58:34 GMT

Enabled the log module and connect the DK to a PC, open up a terminal and read the log.

Baud rate: 115.200
8 data bits
1 stop bit
No parity
HW flow control: None

RE: Regarding BLE data transfer speed

Zero.cool — Mon, 02 Mar 2020 11:04:19 GMT

Hi,
Ok, how the log should be produced,
Using sniffer, or Can I use the Default DK (nrf52840 ) as sniffer and get it.?

Thanks,

RE: Regarding BLE data transfer speed

haakonsh — Mon, 02 Mar 2020 10:28:48 GMT

Your values are invalid. The minimum connection interval is 7.5ms. When your minimum and maximum values are outside of what the given stack you're connected is able to give you, you will usually get a default value that is usually very large.

Again, a log would tell you the actual values that your link is given after parameter negotiations. The values that you set MAX_CONN_INTERVAL, etc, to are desired values, they are not hard-coded, but rather it tells the Central stack what values you would prefer to get.

RE: Regarding BLE data transfer speed

Zero.cool — Mon, 02 Mar 2020 10:10:47 GMT

Hi haakonsh,

Sorry,

forgot to mention connection interval time.

MAX_CONN_INTERVAL 5; //in 1.25 ms units.

MIN_CONN_INTERVAL 3; //in 1.25 ms units.

GATT_MAX_MTU_SIZE 247,

Thanks,

RE: Regarding BLE data transfer speed

haakonsh — Mon, 02 Mar 2020 09:56:10 GMT

You need to log the connection parameters the are negotiated for your specific link otherwise we're just fumbling in the dark. There's not much that can be done to change the state if we do not know what the current state is.

RE: Regarding BLE data transfer speed

Zero.cool — Mon, 02 Mar 2020 09:29:29 GMT

Hi haakonsh,
Thank you for response.

I have already went through above mentioned links.

MTU Length :- 256 (which is max allowed)
PHY - LE 2
Connection event length we have kept variable for slave device to connect(according to my knowledge).
I have tried using PC - Linux- Ble , nrf52840 -DK, Rasp. (with 5.0 BLE) .
But same the speed is not getting increased.

Could you suggest some test which you might have conducted and scenario, I can try them and check your recommendation for max. throughput.

Thanks,

RE: Regarding BLE data transfer speed

haakonsh — Mon, 02 Mar 2020 09:22:34 GMT

First off you need to log what your negotiated connection interval, MTU length, Data Length Extensions/Connection event length, and PHY are for your link. What kind of a device are you connected to, another nRF52/µcontroller, or a smartphone?

These two guides are pretty good:
https://www.novelbits.io/bluetooth-5-speed-maximum-throughput/
https://punchthrough.com/maximizing-ble-throughput-on-ios-and-android/