Disconnect very quickly after connected,reason:0x3E

[jay wang]

Hi Supporter:

Hardware:nRF52840 dongle

Software: basic example "ble_app_interactive", s140_nrf52_6.1.1_softdevice

There is a strange problem,I connect my machine with iphone nrf connect, connect is ok, discovery all normal, But when i use Dongle with the software "ble_app_interactive", It's quickly disconnect.Log:

<info> app: CENTRAL: Connecting...
<debug> app: Connection Request Failed, reason 8
Connected to address: 00 1D 48 2F 18 29
<info> app: CENTRAL: Connected, handle: 0.
<debug> nrf_ble_gatt: Requesting to update ATT MTU to 247 bytes on connection 0x0.
<debug> nrf_ble_gatt: Updating data length to 251 on connection 0x0.
<info> app: Connecting to target 29182F481D00
<info> app: CENTRAL: Disconnected, handle: 0, reason: 0x3E

I test my central dongle with other dongle which use example "usbd_ble_uart",It's connect ok;Log

<info> app: CENTRAL: Connecting...
<debug> app: Connection Request Failed, reason 8
Connected to address: F6 17 FA C0 12 F1
<info> app: CENTRAL: Connected, handle: 0.
<debug> nrf_ble_gatt: Requesting to update ATT MTU to 247 bytes on connection 0x0.
<debug> nrf_ble_gatt: Updating data length to 251 on connection 0x0.
<info> app: Connecting to target F112C0FA17F6
<debug> nrf_ble_gatt: Peer on connection 0x0 requested an ATT MTU of 64 bytes.
<debug> nrf_ble_gatt: Updating ATT MTU to 64 bytes (desired: 247) on connection 0x0.
Current MTU: 64
<debug> nrf_ble_gatt: ATT MTU updated to 64 bytes on connection 0x0 (response).
MTU changed successfully
<debug> nrf_ble_gatt: Data length updated to 251 on connection 0x0.
<debug> nrf_ble_gatt: max_rx_octets: 251
<debug> nrf_ble_gatt: max_tx_octets: 251
<debug> nrf_ble_gatt: max_rx_time: 2120
<debug> nrf_ble_gatt: max_tx_time: 2120
<info> app: Data length updated to 251 bytes.

But when i connect peripheral  dongle with this central dongle first, and then i connect my machin, It's connect ok. 

It's very strange.00-connect_fail.pcapng00-connect_success.pcapng

I use sniffer crab some bags. 

Attachment is my sniffer bags. 

Hope my description is clearly .

Thanks any help.

[jay wang]

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.

[Hung Bui]

Hi Jay, 

 

jay wang said:

The window offset is not 0 when enabled the compat_mode_1.

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

[jay wang]

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.

00-enabled-compat.pcapng

[Hung Bui]

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. 

[jay wang]

OK, Thanks.

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

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