BLE disconnection - NRF_ERROR_RESOURCES

[Roei]

Hi,

I'm using nrf52840 to connect a mobile device via BLE.

I've noticed that when a lot of messages are sent, a disconnection occurs with reason code of NRF_ERROR_RESOURCES.

Can you please help me?

Thanks!

[Kenneth]

Hi,

NRF_ERROR_RESOURCES simply means that the softdevice have already buffered all notification in can hold, so you need to wait until BLE_GATTS_EVT_HVN_TX_COMPLETE event and retry.

Best regards,
Kenneth

[Roei]

Hi,

Just to clarify - NRF_ERROR_RESOURCES is received as an error code for disconnections. Do you think I need to try waiting for BLE_GATTS_EVT_HVN_TX_COMPLETE?

Thanks!

[Kenneth]

If the link have disconnected, then simply ignore the error code, and wait until next connection seems like a reasonable solution.

Kenneth

[Roei]

Sorry, I'm not sure I understand.

How can I prevent the disconnection? Can I increase buffer size?

Thanks

[Kenneth]

Re-reading the case I think I may have misunderstood.

Can you tell me the disconnect reason on BLE_GAP_EVT_DISCONNECTED event?

It should be possible to read this by:
p_ble_evt->evt.gap_evt.params.disconnected.reason

The available disconnect reasons are listed in ble_hci.h, there is no disconnect reason NRF_ERROR_RESOURCES.

[Roei]

Hi,

NRF_ERROR_RESOURCES is the disconnect reason code from p_ble_evt->evt.gap_evt.params.disconnected.reason, after I'm using nrf_strerror_get() to convert it to a string. Am I doing something wrong?

Thanks

[Kenneth]

You can't use nrf_strerror_get(), since it's not an error, it is a reason. I suspect that the value it is converting here is '19', this means BLE_HCI_REMOTE_USER_TERMINATED_CONNECTION. So the peer is disconnecting the link, difficult to say why, I cannot see any reason it should depend on the messages sent.

Kenneth

[Roei]

That is correct - the value is 19. In addition - I can see the log "Generating ECC key pair" from function nrf_ble_lesc_keypair_generate, before disconnection. Do you think it may be related?

Thanks

[Kenneth]

I do not see any reason why that should trigger disconnect, but does the issue go away if you disable LESC support during bonding?

Kenneth

[Roei]

I don't think it's the trigger as well.

However - I've noticed something else - each time disconnection with value 19 occurs - my BLE mobile application disappears, maybe crushed. I think it may be related to overload of messages on the mobile. Does it make sense?

[Kenneth]

Yes, that may explain things yes.

Kenneth

[Roei]

Ok, any ideas what is the reason for application failure when a lot of messages are sent?