nrf52 observer scanning intervals erratic in nrf connect 2.7 when connected as peripheral

RE: nrf52 observer scanning intervals erratic in nrf connect 2.7 when connected as peripheral

Hung Bui — Mon, 28 Oct 2024 12:53:56 GMT

Hi Edward,
Indication should have a confirm in 30 seconds. This could be the reason why you saw a lock up in 30 seconds.
If it's the case, then the issue can be with the peer device, not the one who sends the indication.

Could you try to capture a sniffer trace when you test with indication ? The trace would provide the information about what cause the issue.
Please also capture a trace when you do notification, we can check if it's hitting the max bandwidth. This can explain error -12 when doing notification.

RE: nrf52 observer scanning intervals erratic in nrf connect 2.7 when connected as peripheral

edmcnicholas — Fri, 25 Oct 2024 18:14:31 GMT

It does not lock up if I change to an notify i see an error that should probably be in the indicate as well but it seems to lock up. Since the -12 is ENOMEM.

buf = bt_att_create_pdu(conn, BT_ATT_OP_INDICATE, len);
	if (!buf) {
		LOG_WRN("No buffer available to send indication");
		bt_att_req_free(req);
		return -ENOMEM;
	}

Error

[00:00:37.726,409] <wrn> hfrCentral: Armed MSG Filters matched. Address: EC:C0:85:69:36:93 (random) RSSI: -57 dRSSI 1412
[00:00:37.726,562] <wrn> bt_conn: Unable to allocate buffer within timeout
[00:00:37.726,562] <err> bt_att: Unable to allocate buffer for op 0x1b

RE: nrf52 observer scanning intervals erratic in nrf connect 2.7 when connected as peripheral

edmcnicholas — Fri, 25 Oct 2024 17:48:12 GMT

The scan window. it works but is basically a flat line which is fine for now.

RE: nrf52 observer scanning intervals erratic in nrf connect 2.7 when connected as peripheral

Hung Bui — Fri, 25 Oct 2024 13:47:29 GMT

Hi Edward,
Please clarify what you changed ? You meant to change to notification or to change the scan window=scan interval.
Anyway, please try to capture a sniffer trace and try to reproduce on a sample.

RE: nrf52 observer scanning intervals erratic in nrf connect 2.7 when connected as peripheral

edmcnicholas — Fri, 25 Oct 2024 13:29:49 GMT

I have done that and it does not affect the indicate that is the same either way.

RE: nrf52 observer scanning intervals erratic in nrf connect 2.7 when connected as peripheral

Hung Bui — Fri, 25 Oct 2024 13:26:12 GMT

Hi again,
I'm not 100% sure about switching to notification can solve the issue. Because I'm not 100% sure if error -12 was caused by an ongoing indication or something else. Please try to test with the notification to see if you get the same error.
If you can reproduce the issue with indication on a sample, it would be great.

Please try to test with scan window = scan period to see if it improves.

RE: nrf52 observer scanning intervals erratic in nrf connect 2.7 when connected as peripheral

edmcnicholas — Fri, 25 Oct 2024 12:47:42 GMT

Also if I do the same scan interval and window it looks to stay in RX the entire time.

RE: nrf52 observer scanning intervals erratic in nrf connect 2.7 when connected as peripheral

edmcnicholas — Fri, 25 Oct 2024 12:46:38 GMT

If i were to switch this to a notify would that work better and not hang as it does not require a response or can I look and see if there is a pending indicate. These can be sent at very high rate but don't need to be.

RE: nrf52 observer scanning intervals erratic in nrf connect 2.7 when connected as peripheral

Hung Bui — Fri, 25 Oct 2024 07:41:06 GMT

Hi Edward,

Could you reproduce the issue with a sample ?
Can you capture a sniffer trace ?
You may have error -12 with indication when there is a ongoing indication not confirmed yet. I suspect that it was because there were packet drop due to bad scheduling. A sniffer trace would be able to tell that.
How often do you send the indication ?

RE: nrf52 observer scanning intervals erratic in nrf connect 2.7 when connected as peripheral

edmcnicholas — Thu, 24 Oct 2024 13:05:19 GMT

It looks like the indicate function if very different in 2.7 as well

RE: nrf52 observer scanning intervals erratic in nrf connect 2.7 when connected as peripheral

edmcnicholas — Thu, 24 Oct 2024 13:00:17 GMT

The indicate is sent out when we receive a broadcast message to the central takes a long time to fail with error -12 it looks like it is locking up for a good 30s and this was also not the case in 2.6 is there a buffer that needs to be increased? a lot of these messages get received.

int rc = bt_gatt_indicate(NULL, &g_armed_char_ind_params);
    if (rc)
    {
        LOG_WRN("Armed Indicate failed: %d", rc);
    }

[00:02:36.018,371] <wrn> hfrCentral: Armed MSG Filters matched. Address: EC:C0:85:69:36:93 (random) RSSI: -63 dRSSI 2818
[00:03:05.906,463] <wrn> bt_det: Armed Indicate failed: -12

RE: nrf52 observer scanning intervals erratic in nrf connect 2.7 when connected as peripheral

Hung Bui — Thu, 24 Oct 2024 12:31:55 GMT

Hi Edward,
If you look at the documentation here: https://docs.nordicsemi.com/bundle/ncs-2.7.99-cs2/page/nrfxlib/softdevice_controller/doc/scheduling.html

You can find that the scanner (which windows is not equal to interval) can get 4th priority which is lower than advertising/connection. This is not listed in the documentation in v2.6.0
This may explain why the scheduling looks different between v2.6.0 and v2.7.0.

Back to your issue, you mentioned "it hangs on indicate events seemingly locking up the devices Bluetooth" could you explain ?

One suggestion to avoid this issue is to do scan interval = scan windows. This will utilize the timeslot better (any available free timeslot will be used for scanning)

Could you give some more info about your application ?

RE: nrf52 observer scanning intervals erratic in nrf connect 2.7 when connected as peripheral

edmcnicholas — Thu, 24 Oct 2024 10:56:28 GMT

It's actually the connection causing the issue it is fine while advertising

RE: nrf52 observer scanning intervals erratic in nrf connect 2.7 when connected as peripheral

Hung Bui — Thu, 24 Oct 2024 10:50:36 GMT

Hi Edward,

I'm taking over the ticket from Håkon.
I have reproduced the issue here. It seems that there is some change in the scheduler algorithm from v2.7.
I am checking internally with the team to see why that happen and if there is anyway you can have the scanner having more priority over the advertiser.

RE: nrf52 observer scanning intervals erratic in nrf connect 2.7 when connected as peripheral

edmcnicholas — Mon, 21 Oct 2024 13:11:13 GMT

Here is the dis peripheral sample with a scanner running with a delayable kwork that switches the interval.

2.7 one interval at 500/250 all others 500/50 or shorter.

2.6.2 500/250ms windows

devzone.nordicsemi.com/.../peripheral_5F00_dis_5F00_scan.zip

RE: nrf52 observer scanning intervals erratic in nrf connect 2.7 when connected as peripheral

Elfving — Mon, 21 Oct 2024 08:49:06 GMT

Are you able to show this difference or reproduce this issue with something more minimal, or a sample from the SDK? I would like to reproduce this on my side here.

Regards,

Elfving

RE: nrf52 observer scanning intervals erratic in nrf connect 2.7 when connected as peripheral

edmcnicholas — Fri, 18 Oct 2024 13:26:39 GMT

I am using sysbuild in the 2.7 build and the child image for 2.6.2. I am running the exact same prj.conf on an nrf52840 and the only difference is the version of the SDK. This code has been working through multiple versions of the SDK for the last several years since my initial release.

RE: nrf52 observer scanning intervals erratic in nrf connect 2.7 when connected as peripheral

Elfving — Fri, 18 Oct 2024 13:21:17 GMT

Hello Edward,

So yeah, you are not building using the new "sysbuild" then? And you are not building this directly from the SDK folder (maybe by modifying a sample or something), as that might also make it build using sysbuild?

I should also mention that the VSC extensions functionality is also a bit limited in 2.7, but if this is an older project that you've just copy-pasted a few files to I guess you haven't modifed any of these files in the VSC GUI either?

You are using NRF52, so I guess this isn't relevant either. I am not really seeing anything here either, but let me know something catches your eye. What nRF52 Soc is it?

Regards,

Elfving

RE: nrf52 observer scanning intervals erratic in nrf connect 2.7 when connected as peripheral

edmcnicholas — Thu, 17 Oct 2024 15:08:49 GMT

I can confirm that this is not the code porting to more device tree oriented code as I just used the same project with the old board files and child image build system. This is definitely an issue with the soft device.