CC2564C: Delay needed before connection parameters update?

Morten T

Part Number: CC2564C

Hi. I'm using CC2564C in a peripheral, connecting to various smarthphones etc. I use a 3rd party Host stack and UART HCI. This issue was found using patch 1.3, but also persists if I update to 1.4 In the peripheral, U want to request a connection parameter update after a connection has been established. In some cases, this does however fail and the connection is lost.

Two conditions seem to be needed in order to see the issue:

Connection parameter update request has to be sent right after the connection is established. Delaying for a few hundred milliseconds seem to resolve the issue.
It only seems to fail towards certain LE master devices. It fails rather consistently towards iPhone SE 2nd gen and in some cases against some Samsung tablets.

I can see from sniffer logs that in the failing scenarios, the connection parameter is sent to the master immediately when the connection is established, even before version and feature exchange. Short thereafter, the CC2564C loses track of the connection. A simple workaround is to add a delay before sending the request, but I would like know a bit more about this issue in order to determine a suitable delay and have not been able to find any information about this on the web or in the forum. Some questions:

Can you confirm if this is expected or unintended behavior in the controller?
Please advise on selecting the right delay before sending connection parameter update request over HCI in case that cannot be fixed in other ways.

I have attached a sniffer log taken with Wireshark. The issue starts at packet #2067.

Thanks, Morten

iphone_se_connect_fail.pcapng.gz

over 5 years ago

0 Hari Nagalla over 5 years ago

TI__Mastermind 27090 points

We, are not aware of the delay need.. Can, you take FW logs to check, if there are transaction collisions happening with your timing..

ThanksCC256x Logger User Guide - Texas Instruments Wiki.pdf

0 Morten T over 5 years ago in reply to Hari Nagalla

Prodigy 30 points

Hi Hari,

I managed to capture logs from the TX_DBG pin, the files are attached here. I had to add .gz to the file name of the logger file as the forum does not allow me to upload .lgr files. The file is not gzipped so just rename it before loading.

Looking more into details, it seems the connection is lost during LL_FEATURE_REQ/RSP exchange, which happen immediately after the new connection parameters have been applied.

In the logger trace, the following happens:

CONNECT_IND around #1146
Update parameters received around #1205, applied around #1271
LL_FEATURE_REQ received from master around #1278.
LL_FEATURE_RSP sent but then sync is lost.

In the Wireshark trace, CONNECT_IND is sent in packet #324.

I hope this is useful for you, otherwise please let me know. Thanks in advance for your help

/Morten

logger_iphone_se_connect_fail2.lgr.gz 8284.iphone_se_connect_fail2.pcapng.gz

0 Hari Nagalla over 5 years ago in reply to Morten T

TI__Mastermind 27090 points

It appears, there is a transaction collision. Can, you also provide the FW logs, where the connection update was successful.

Thanks

0 Morten T over 5 years ago in reply to Hari Nagalla

Prodigy 30 points

Hi Hari,

Attached Logger and Wireshark traces. Same procedure as last time regarding file names.

In logger trace, connect happens around #22984. In Wireshark trace it happens around #1485.

/Morten

logger_iphone_se_connect_ok2.lgr.gz

iphone_se_connect_ok2.pcapng.gz

0 Hari Nagalla over 5 years ago in reply to Morten T

TI__Mastermind 27090 points

Thanks for the logs. I will compare and get back in a day..

Thanks

0 Hari Nagalla over 5 years ago in reply to Hari Nagalla

TI__Mastermind 27090 points

Hi Morten,

Reviewed the failed log:

For the failed case, due to some reason the 'instant' in the wireshark message shows '11', where as the controller shows it is '12'. It appears due to this reason the connection event sync is getting lost.. For now, as a work around delay the sending of the 'connection parameter update request'. I will look into further, of there is a minimum 'instant' i.e number of connection events after a connect needed for the parameter update..

Where, as in the logger (se_connect_fail2.lgr) it shows -

1208 02:07:52.044 -0:00:00.018 start peer transaction WB_LL_CONNECTION_UPDATE_REQ, connection index = 0, current 0 local 0
1209 02:07:52.044 -0:00:00.018 ULP con update win size 3, win offset 0, interval 12, latency 0
1210 02:07:52.044 -0:00:00.018 ULP con update: timout 72, instant 12, current 4

Thanks

Bluetooth®︎

Bluetooth forum

CC2564C: Delay needed before connection parameters update?