nRF52832 Central device cannot receive Notifications from another nRF52832 peripheral

RE: nRF52832 Central device cannot receive Notifications from another nRF52832 peripheral

ovrebekk — Tue, 11 Jun 2024 13:00:41 GMT

Hi Dimitra

Good to hear you found the issue, and thanks a lot for reporting the solution. I was just about to look more into your traces, so the timing was good 😉

Best regards
Torbjørn

RE: nRF52832 Central device cannot receive Notifications from another nRF52832 peripheral

DimitraN — Tue, 11 Jun 2024 11:38:35 GMT

Hello again, after more testing, I finally found the bug which was irrelevant to all the above.
The bug was on the write function to the Write Characteristic and regarding about the type of data I send.

[quote userid="128023" url="~/f/nordic-q-a/111919/nrf52832-central-device-cannot-receive-notifications-from-another-nrf52832-peripheral"]function to write the uint8_t array in 0x0001 Characteristic[/quote]

In this function i had to change
this line:

write_req.params.gattc_write.p_value  = (uint8_t *)&subscribe;

to this:

write_req.params.gattc_write.p_value  = (uint8_t *)subscribe;

because the subscribe is already an array...

I am so sorry for creating such an issue and for spending your time on a question which was caused by another problem.

By the way, always thankful for your assistance!
Best regards,

Dimitra

RE: nRF52832 Central device cannot receive Notifications from another nRF52832 peripheral

DimitraN — Mon, 10 Jun 2024 14:41:12 GMT

Yes sure, I edited the answer above with the zip file, and one more question and observation.

Thank you

RE: nRF52832 Central device cannot receive Notifications from another nRF52832 peripheral

ovrebekk — Mon, 10 Jun 2024 12:56:38 GMT

I will take a look at the details and get back to you tomorrow. Do you mind attaching the sniffer traces directly rather than just sending screenshots?

You can simply drag drop a file into your reply to attach it (using zip is easier if you have multiple files).

Regards
Torbjørn

RE: nRF52832 Central device cannot receive Notifications from another nRF52832 peripheral

DimitraN — Mon, 10 Jun 2024 10:56:59 GMT

[quote userid="2116" url="~/f/nordic-q-a/111919/nrf52832-central-device-cannot-receive-notifications-from-another-nrf52832-peripheral/488067"]One thing I spotted in the log is that you have a CCCD handle of 36, which implies that you have a pretty long GATT table? Are you sure this is correct? [/quote]

The Services and Characteristics are more than I said, apart from the Generic Access, Generic Attribute, there are:
Device Information (0x180A)
Battery Service (0x180F)
UnknownService (0xFDF3)
UnknownService(0x2252) :the one that I mentioned and which is the only one I want to have access to.

[quote userid="2116" url="~/f/nordic-q-a/111919/nrf52832-central-device-cannot-receive-notifications-from-another-nrf52832-peripheral/488067"]Have you tried to capture some sniffer traces of the two cases, first when using the nRF Connect app and it's working fine, and then with your own central which is not working? [/quote]

I tried now for the first time, I haven't used it before, I will present below the logs from Sniffer.

here are the logs when my phone with nRF Connect app connects to the peripheral device.

here is the moment I write/subscribe to the write characteristic and to the cccd for the Notify

and here when I receive the Notification data

Versus when Central-Peripheral Device connects with the peripheral

1st difference here is that my Central Device performs bonding, which I thought wouldnt cause a problem. Maybe I should deactivate it.

And here is when I Write to the Write characterstic

So, 2nd difference is that my device tries to write to the characterstic of another Service (in the parenthesis it says Amersports, which is another service of the peripheral device) .

However, in my code,

#define SENSOR_UUID_SERVICE             0x2252
#define NOTIFY_CHARACTERISTIC           0x0002
#define WRITE_CHARACTERISTIC            0x0001

I let the Central device have acknowledge for only 0x2252 Service which is the only one I want it to communicate with, and with which I get the confirmation that it succesfuly discovered the Service and Characteristics,

these are the logs during connection.
So I thought that it scans and discovers and assigns the connection handles to this Service and Characteristics only, and ignore others. (The Amersports service also has 2 characterstics 0x0001, 0x0002)
Here are the 2 Services in nRF Connect App:

Edit: I saved the traces into files (and also included them in text type)

devzone.nordicsemi.com/.../8055.Wireshark_2D00_sniffertraces.zip

In the folder, I also included the Log file from nRF Connect when my phone connects with the Peripheral device

1. From the Sniffer, do you agree that the conclusion is that it probably writes and enables the characterstics of the other Service?
2. If that is the case, how do I solve this problem, that my device must look only at the specific service?
3. If this is not the case, what else could be the problem, if the Sniffer helps ?

Edit: 4. Finally, this time I also captured the sniffer traces on the Central device side, and I noticed that when it attempts to write something on the write characteristic or on cccd there is a message "Encrypted packet decrypted incorreclty (bad MIC)". What does this mean? Could it be relevant?

RE: nRF52832 Central device cannot receive Notifications from another nRF52832 peripheral

ovrebekk — Mon, 10 Jun 2024 09:14:54 GMT

Hi Dimitra

Have you tried to capture some sniffer traces of the two cases, first when using the nRF Connect app and it's working fine, and then with your own central which is not working?

Then it should be quite easy to figure out what is different in the two cases, which should hopefully point to a solution.

One thing I spotted in the log is that you have a CCCD handle of 36, which implies that you have a pretty long GATT table? Are you sure this is correct?

If you only use two characteristics I wouldn't expect you to reach a handle of 36.

Best regards
Torbjørn