BLE Discovery Service Can Not Find Service

[ctzn]

Hi,

I have a hardware that I want to connect via BLE and send data via NUS (Nordic UART Service). I can connect to this hardware via the NRF Connect application on android and see the service UUIDs in the Client tab. When I want to connect to the same hardware using the central_uart sample in the nrf Connect SDK, it says no service found in RTT. Therefore, I cannot send data over BLE. I am running the uart_central sample on the nRF52833 DK.

The advertise interval of the hardware I want to connect to is 4750 ms, slightly higher than other hardware. So should I change a parameter in the config?

RTT logs are listed below.

00> [00:00:18.700,286] <inf> central_uart: Filters matched. Address: EE:C4:00:98:C8:2D (random) connectable: 1
00> [00:00:18.744,689] <inf> central_uart: Connected: EE:C4:00:98:C8:2D (random)
00> [00:00:18.896,270] <inf> central_uart: MTU exchange done
00> [00:00:18.996,032] <dbg> bt_gatt_dm.discovery_callback: NULL attribute
00> [00:00:18.996,063] <dbg> bt_gatt_dm.discovery_complete_not_found: Discover complete. No service found.
00> [00:00:18.996,063] <dbg> bt_gatt_dm.svc_attr_memory_release: Attr memory release
00> [00:00:18.996,215] <inf> central_uart: Service not found
00> [00:00:44.817,108] <wrn> central_uart: Failed to send data over BLE connection(err -128)
00> [00:00:44.967,193] <wrn> central_uart: NUS send timeout
00> [00:00:44.967,193] <wrn> central_uart: Failed to send data over BLE connection(err -128)
00> [00:00:45.117,309] <wrn> central_uart: NUS send timeout

 Edit: In the uart_central sample I just edited the filter to be device_name. Other than that, no changes were made.

[Simonr]

Hi

Sorry about the late reply, but I've been out of office most of last week and I'm just now catching up to my backlog. 

I don't think these issues come from the scan filter you're using, as it seems specifically related to the discovery manager. Are you sure you didn't change anything in the discovery procedure at all? If not, is the NUS service actually advertised by the peripheral. The nRFConnect app searches for all kinds of services which is also why it takes longer, while the central UART should only care about the NUS service. This still doesn't explain why the central isn't able to discover the NUS service. 

The "NULL attribute" message points to the discovery callback not getting any attributes, so I guess the peripheral isn't providing these to the central for some reason.

Best regards,

Simon