nRF52840 with SDK 15.2 running with BLE and Data Length Extension

[SebastianGutzwiller]

Hi all,

I observe a connection supervision timeout (HMI error code 0x08) in my Nordic firmware with certain Android smartphones (controller).

Additional info regarding GATT events: After the last connection parameter update and some GATT events the softdevice stops reporting BLE_GATTS_EVT_HVN_TX_COMPLETE and BLE_GATTS_EVT_WRITE.

After exchanging the MTU request in GATT the controller sends data length update requests over GAP with

• Max number of payload octets to receive of  251 bytes
• Max reception time of 2120 us
• Max number of payload octets to transmit of  135 bytes
• Max transmission time of 1192 us (BAD CASE) and 2120 us (GOOD CASE)

Any ideas?

[Amanda Hsieh]

Hi, 

Error Code 0x08 is an BLE_HCI_CONNECTION_TIMEOUT (supervision timeout, i.e. you have not received any packets from the peer in x seconds). 

Is this a custom board? Have you tried the same code on the nRF52840 DK? Does it happen there?

Could you try to debug to find which function returned this error code?

-Amanda H.

[SebastianGutzwiller]

Yes, the firmware is running on the nRF52840 DK.

The error comes as reason for BLE_GAP_EVT_DISCONNECTED in our event handling observer.

HTH Sebastian

[Amanda Hsieh]

Hi,

If your BLE peripheral is in a connection with a central, and the central stops responding for so long that the supervision timeout triggers, you will get the event BLE_GAP_EVT_DISCONNECTED with reason BLE_HCI_CONNECTION_TIMEOUT (0x08).

I suspect either peripheral or central is asserting, and when one side assert, it will by default do a system reset and start over again. This will be observed as BLE_HCI_CONNECTION_TIMEOUT on the other side.

To find what is causing the assert you need to define DEBUG and set a breakpoint in app_error_fault_handler() to find file name, line number, and error code.

-Amanda H.

[SebastianGutzwiller]

Hi,

We don't have an assertion in the SDK of our firmware.

Sebastian

[SebastianGutzwiller]

Hi,

In the attachments you see the Link Layer message sequences over the air for both the good & bad case.

Sebastian