DevAcademy Bluetooth LE connection problems

[Lars M]

Hi,

I am going through the DevAcademy Bluetooth LE lessons, using nRF5 DK. But I run into problems directly in the exercise of the first lesson. Everything goes fine to step 4.2, but connecting doesn’t work. Connection is established, but almost immediately disconnection happens. LED2 is lit for a short moment. The print outs are like this:

No matter how many times I try, disconnection always happens this way. I have also tested to connect via the Bluetooth low energy desktop app using the Nordic BLE dongle. Then the connection works fine. I have tested with both nRF Connect SDK 2.3.0 and 2.0.0, and the scenario is the same for both versions.

In the desktop app it is possible to read the button state and activate notifications (and receive updates when the button is pressed). But I am not able to control LED3. I have put a breakpoint in write_led() in lbs.c (C:\...\v2.3.0\nrf\subsys\bluetooth\services\lbs.c), but the breakpoint isn't hit when I write to the LED characteristic. Though, a breakpoint in read_button() will be hit when I click "Nordic LED and Button Service", so I should be in the correct file.

 

Best regards,

Lars

[Lars M]

Hi again,

The last part in previous post is solved. I had to restart my computer, and after that there is no automatic connection.

/Lars

[Einarh]

Lars M said:

After the last part of lesson 3 exercise 2, connection always works. And that part has to do with some connection parameters (data length and time).

Then it seems like this was the tweaking of parameters needed to make it work, and it also seems like your phone remembers these parameters. Hard to say exactly what made the difference without being able to reproduce the error though.

Lars M said:

Can you say something about the red mark in packet 214? Why is it red when corresponding packet in another capture is not red? They look pretty much the same, apart from the red-marked comes after LL_CONNECTION_UPDATE_IND.

The red mark seems to indicate an unexpected sequencing of packets yes, the peripheral sending a PHY_REQ when the central expects a reply to its CONNECTION_UPDATE_IND.

[Lars M]

Einarh said:

Then it seems like this was the tweaking of parameters needed to make it work, and it also seems like your phone remembers these parameters.

Ok, it's maybe like that. Though, it would be nice to know it for sure. But maybe it's hard to get to know that.

But if it is like this, these update of parameters used in lesson 3 exercise 2 should be present in all BLE-programs to prevent a phone to behave like mine.

/Lars

[Lars M]

Hi again,

Another thing that makes this not really satisfactory is that I had my phone working with my own-made BLE-project at the same time as the phone didn't work with the DevAcademy-projects. For my project, the phone didn't send LL_CONNECTION_UPDATE_IND as every other time when the connection works.

Lars M said:

I have made my own BLE-program (called MMS), which is a light version of NUS. Here the connection works fine. It is also possible to send characters to and receive notifications from my dk, and also disconnect. The only difference in the connection process seems to be the lack of LL_CONNECTION_UPDATE_IND in my project.

So maybe there is more to this than just the possibility that the parameter updates have made my phone behave in a new way. It obviously behaved differently depending on project before.

/Lars

[Lars M]

It feels this never comes to an end. Now I have run lesson 4 exercise 1, and now the connection problem is back. Lesson 3 exercise 2 works fine, and also MMS. But when I go back to lesson 4 exercise 1, the connection problem is still there, the phone hasn't changed behaviour (at least not to make this program work). I also tried lesson 1, and now that works.

I have captured a lot. I attach the files, numbered in the order they are logged. Though, actually there is nothing new. Every time conenction works, LL_CONNECTION_UPDATE_IND is missing. And every time connection doesn't work, LL_CONNECTION_UPDATE_IND is present.

/Lars

1 Capture dk first phone less4 exer1 not working, before less3 exer2.pcapng

2 Capture dk first phone MMS working, before less3 exer2.pcapng

3 Capture dk first phone less4 exer1 not working, before less3 exer2 after MMS.pcapng

4 Capture dk first phone less3 exer2 working.pcapng

5 Capture dk first phone less4 exer1 not working, after MMS after less3 exer2.pcapng

6 Capture dk first phone less1 exer1 working, after MMS after less3 exer2.pcapng

7 Capture dk first phone less4 exer1 not working, after MMS after less3 exer2 after less1.pcapng