BLE data write delay

[FormerMember]

Hello, all

I have a problem with ble data exchanging.

I have programmed an application which controls servo motors through phone application.

At the connection, ble data is sent immediately by clicking phone app button,

but the problem is that it lasts only few seconds.

After 3~4 sec, data exchanging has a delay and operates like a queue.

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please watch this link.

As you can see, data exchange has delay 3~4 sec later and it operates past event even I don't click app button.

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So I found solution but it also has another problem.

I set CONN_SUP_TIMEOUT to MSEC_TO_UNITS(10000, UNIT_10_MS) from MSEC_TO_UNITS(4000, UNIT_10_MS)

data exchanging has no delay permanently, but after 1~2 minute the connection is disconnected.

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Here is the link.

Unlike first video, there is no delay but after 1-2 minute the connection is lost.

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I also changed value of MIN_CONN_INTERVAL and MAX_CONN_INTERVAL, but the result has delay or disconnection event.

How do I exchange ble data without delay and diconnection event?

[Hung Bui]

@TY: Could you capture some sniffer trace when the issues happen ?

If you don't do writing but wait for a while or if you press the button with slower speed, would you have the delay and the disconnection ?

I suspect that it could be either the phone buffer was over flow when you send to many write command , or it was the connection interval was changed to a longer one.

[FormerMember]

Even I press the app button with slower speed, delay exist. or if I set MIN_CONN_INTERVAL to MSEC_TO_UNITS(10000, UNIT_10_MS) or lager, disconnection must happen.

[Hung Bui]

You should not set the connection interval to too large. For testing purpose you should try to set it as low as possible. Please try to capture a sniffer trace.

[FormerMember]

Here is the capture.

This capture is showing that ble data exchanging has delay and operate past data even I dont press the app button after about 3~4 sec at the connection.

please watch this video

[FormerMember]

I find how to fix it.

The problem is MAX_CONN_PARAMS_UPDATE_COUNT.

MAX_CONN_PARAMS_UPDATE_COUNT is basically set to 3

and NEXT_CONN_PARAMS_UPDATE_DELAY is set to 30.

So after about 1m 30s, the ble_conn_params timeout event call on_conn_params_evt() and operate sd_ble_gap_disconnect().

The solution is that set sd_ble_gap_disconnect() comment or remove in on_conn_params_evt().

But I dont understand why it wasnt disconnceted if I set MIN_CONN_INTERVAL to 450, MAX_CONN_INTERVAL to 550 and CONN_SUP_TIMEOUT to 4000. It should be disconnected after 1m 30s technically but woldnt, only make delay and operate past data.

Now I set MIN_CONN_INTERVAL, MAX_CONN_INTERVAL and CONN_SUP_TIMEOUT to whatever I want, I dont get delay and disconnection.