Disconnect very quickly after connected,reason:0x3E

RE: Disconnect very quickly after connected,reason:0x3E

jay wang — Tue, 09 Mar 2021 08:34:56 GMT

Hi Hung:

I modify connect parameter, It's connect success now.Thank goodness.

Modification:

Parameter Origin Value Modified Value

NRF_BLE_SCAN_MIN_CONNECTION_INTERVAL 100 10

NRF_BLE_SCAN_MAX_CONNECTION_INTERVAL 300 30

NRF_BLE_SCAN_SLAVE_LATENCY 5 0

NRF_BLE_SCAN_SUPERVISION_TIMEOUT 6200 720

I enabled compatibility mode.

Now connect success rate is very high, Fail occasionally.

Think you for your help.

Cheers.

RE: Disconnect very quickly after connected,reason:0x3E

jay wang — Tue, 02 Mar 2021 12:50:50 GMT

OK, Thanks.

I am agree with you, It's an incompatibility issue.

I'll try your ideas. I will tell you if any update.

RE: Disconnect very quickly after connected,reason:0x3E

Hung Bui — Tue, 02 Mar 2021 12:45:37 GMT

Hi Jay,
It could be an incompatibility issue with the Linux device you have.

I'm not 100% sure why it doesn't work with our device, but you may want to check the clock source of the Linux device. It seems to me that it has wrong clock configuration (specifically crystal/RC tolerance) that make it missed the window size.

I'm not sure if it helps but you can try to reduce the LFCLK tolerance on the nRF52 , it might help in this case. Other than that I ran out of idea on how to fix this.

RE: Disconnect very quickly after connected,reason:0x3E

jay wang — Tue, 02 Mar 2021 01:08:57 GMT

The window offset always equal the connect interval when i enabled compat_1_mode.I add the sniffer trace in attachment:00-enabled-compat.pcapng.Please check it.

devzone.nordicsemi.com/.../00_2D00_enabled_2D00_compat.pcapng

RE: Disconnect very quickly after connected,reason:0x3E

Hung Bui — Mon, 01 Mar 2021 16:22:49 GMT

Hi Jay,

[quote user="jay wang"]The window offset is not 0 when enabled the compat_mode_1.[/quote]

Could you clarify what's the window offset was ? was it 0 or something else ? Could you provide a sniffer trace ?

RE: Disconnect very quickly after connected,reason:0x3E

jay wang — Mon, 01 Mar 2021 15:19:45 GMT

Thanks for reply.

I have found the compatibility mode today,But unfortunatly, This phenomenon is still hanppening.I catch the packet with sniffer,The window offset is not 0 when enabled the compat_mode_1.I'm sure that my setting is taken effort.

I've run out of my ideas.

RE: Disconnect very quickly after connected,reason:0x3E

Hung Bui — Mon, 01 Mar 2021 10:32:25 GMT

Hi Jay,
Thanks for the info. There are some devices that don't support window offset = 0 . We have created a compatibility mode to avoid using window offset = 0.
Please have a look at the ble_gap_opt_compat_mode_1_t struct quoted here:

/**@brief Compatibility mode 1 option.
 *
 * @details This can be used with @ref sd_ble_opt_set to enable and disable
 *          compatibility mode 1. Compatibility mode 1 is disabled by default.
 *
 * @note Compatibility mode 1 enables interoperability with devices that do not support a value of
 *       0 for the WinOffset parameter in the Link Layer CONNECT_IND packet. This applies to a
 *       limited set of legacy peripheral devices from another vendor. Enabling this compatibility
 *       mode will only have an effect if the local device will act as a central device and
 *       initiate a connection to a peripheral device. In that case it may lead to the connection
 *       creation taking up to one connection interval longer to complete for all connections.
 *
 *  @retval ::NRF_SUCCESS Set successfully.
 *  @retval ::NRF_ERROR_INVALID_STATE When connection creation is ongoing while mode 1 is set.
 */
typedef struct
{
   uint8_t enable : 1;                           /**< Enable compatibility mode 1.*/
} ble_gap_opt_compat_mode_1_t;

This mode can be enabled by calling sd_ble_opt_set().

I don't think there is an option to do this in the CLI interface, but you can add the call directly in the code of ble_app_interactive.

RE: Disconnect very quickly after connected,reason:0x3E

jay wang — Mon, 01 Mar 2021 02:28:29 GMT

Hi Hung:

My slave details:

> HCI Event: LE Meta Event (0x3e) plen 19
LE Connection Complete
status 0x00 handle 1025, role slave
bdaddr F5:CC:F0:5F:A0:DE (Random)
< ACL data: handle 1025 flags 0x00 dlen 16
L2CAP(d): cid 0x0005 len 12 [psm 0]
Connect: de:a0:5f:f0:cc:f5
> HCI Event: Number of Completed Packets (0x13) plen 5
handle 1025 packets 1
> HCI Event: Disconn Complete (0x05) plen 4
status 0x00 handle 1025 reason 0x3e
Reason: Connection Failed to be Established
< HCI Command: LE Set Advertise Enable (0x08|0x000a) plen 1
2020/10/31 22:48:16 l2conn: 0x0401 already disconnected
Disconnect: de:a0:5f:f0:cc:f5
> HCI Event: Command Complete (0x0e) plen 4
LE Set Advertise Enable (0x08|0x000a) ncmd 1
status 0x00

RE: Disconnect very quickly after connected,reason:0x3E

jay wang — Sat, 27 Feb 2021 11:05:25 GMT

Hi Hung Bui,

Good weekend, Thanks for your reply.

For you question:

1.How often do you see the issue- every time.when i connect it first.

2.Have you even managed to connect the central to the peripheral - My "nRF52840 dongle" connect to iphone is ok.But it's cannot connect to my MACHINE(It's linux host and maybe TI chip,not very sure).

3.Have you tried to connect using a phone to your peripheral- Yes ,My iphone connect to my MACHINE is ok, Not any problem.I use the app NRF CONNECT.

4.Please try to test with a normal BLE application in the SDK-- My application is used the example "ble_app_interactive" which is in the SDK.

5.Could you check the log on the peripheral-- I can see the log in my MACHINE (Use the HCIDUMP tool in linux host).It's can dicovery my central device, and putout the correct mac address, But it's display disconnect very soon .I can send the log to you in monday.

And i want to expain the attachment

00-connect_fail.pcapng : This packet is the process which connected fail.

00-connect_success.pcapng : When my nRF52840 Dongle have connected a peripheral before, I can connect my MACHINE as second link success, This packet is the proccess which connect success as second link.

It's can connect success when it's as second link, This is why i feel so strange.

If the slave cannot catch the connect request, why is connect success as sencond link? I compare the "fail "and "success" packet, The connect request content different is "window offset", I suspect this filed cause this problem,But the window offset and window size cannot set through soft device.

RE: Disconnect very quickly after connected,reason:0x3E

Hung Bui — Fri, 26 Feb 2021 14:48:48 GMT

Hi Jay,

[quote user=""]<info> app: CENTRAL: Disconnected, handle: 0, reason: 0x3E[/quote]

Disconnected reason 0x3E means: BLE_HCI_CONN_FAILED_TO_BE_ESTABLISHED.
This matched with what I can observe in the sniffer trace. The central sent the connect request but there was no response from the peripheral.

There could be a few posibilities:

1. The slave didn't catch the connect request from the central. How often do you see the issue ? Have you even managed to connect the central to the peripheral ? Have you tried to connect using a phone to your peripheral ? Please try to test with a normal BLE application in the SDK.
2. The slave caught the connect request but couldn't send the response packet due to timing issue. Could you check the log on the peripheral ? If it's the case the log on the peripheral should also show that it's connected but then quickly disconnected.

RE: Disconnect very quickly after connected,reason:0x3E

jay wang — Fri, 26 Feb 2021 01:43:46 GMT

Some notice:The connect exchange data is locate the end of captue package.Lot's of advertisement in the front of package.