Issue of disconnection within 1 minute with iPad Pro (A1673)

[saka4849]

Flash nRF5_SDK_15.2.0 ble_app_uart in PCA10056 without editing,
It occurs regardless of iOS Apps (nRF Connect / nRF Toolbox / LightBlue) when connected with iPad (A1673 iOS13.2).
It does not occur on iPad Air2 (A1566 iOS13.2) or iPad Pro3 (A1876).

It occurs even if sd_ble_gap_disconnect in project is commented out.
There is no error in Sniffer. (File reference)

Interval Max * (Slave Latency + 1) ≤ 2 seconds
Interval Min ≥ 20 ms
Interval Min + 20 ms ≤ Interval Max
Slave Latency ≤ 4
connSupervisionTimeout ≤ 6 seconds
Interval Max * (Slave Latency + 1) * 3 < connSupervisionTimeout

I follow these Apple guidelines.

• SLAVE_LATENCY：0
• connSupervisionTimeout：4s
• Interval Min：20ms
• Interval Max：75ms
• FIRST_CONN_PARAMS_UPDATE_DELAY：5000ms
• NEXT_CONN_PARAMS_UPDATE_DELAY：30000ms

Please help me with your advice...

SDK:nRF5_SDK_15.2.0
SD:s140_nrf52_6.1.0_softdevice.hex

cap.pcapng　

[Simon]

I am sorry for the delay, I am currently looking into your issue and will try to provide you with an answer as soon as possible.

Best regards,

Simon

[saka4849]

Thank You Simon!! I got it.
I'm looking forward to your reply.

Thanks and Best regards.

saka

[Simon]

It seems like the link layer of the iPad (A1673 iOS13.2) is misbehaving, due to the same reasons explained in this ticket.

Best regards,

Simon

[saka4849]

My Wireshark capture and the ticket are same.
By the way, when I update to v6.1.1, it was not disconnected even with the same FW!
Did you change anything in SD?
Is there a Release note with the changes?

Thanks and Best regards.

saka

[Simon]

I am sorry for the delay. Lately, a huge portion of the support team has been on Christmas vacation. Most of the staff will be back 6 of January 2020 and you can be sure to get an answer shortly after that.

Best regards,

Simon

[Simon]

Does this mean your issue is resolved? If you download SoftDevice S140 from here, you will get the release notes with changes as well.

Best regards,

Simon

[saka4849]

Thanks, this issue is resolved.

Fixed an issue where the SoftDevice would sometimes delay the LL_LENGTH_RSP in a Data Length Update procedure if a PHY Update procedure was ongoing at the same time (DRGN- 10853).

The bug fix is resolved this issue.