Moto E4 fails to connect with nRFConnect app itself (Error 0x85 - GATT ERROR)

[jmuralinux]

Hi All,

Moto E4 mobile phones do not connect right away and at times takes few minutes and connects eventually. Right after I hit connect I get an error 0x85(GATT ERROR) and the app is in connecting state for a while and at times it connects, but some times it's stuck in connecting. Even when it is connected, if I try to do a write operation, the app doesn't show any error but the other side(firmware) doesn't get any data.

This firmware works with various phones like Samsung S7, LG V20, LG Pheonix, Moto Nexus, all iPhone models, etc. Issue is observed only with Moto E4 running Android 7.1.1. From the firmware side, it sees connected event and gets disconnected within a second, but in the app, it still shows connecting and the firmware again gets connected event and disconnects again. The issue is reproducible most of the times and it rarely connects properly doing MTU exchange and other handshakes.

nRF BLE sniffer shows Connect event from the app and nothing else. So no clue on what is that phone is missing that stops it from communicating to the firmware.

As you can see in the attached capture, the CONNECT_REQ event is there and stuck for about 30 seconds without any other activity. Please refer to Line 1526 of the capture.

Any help on this issue is much appreciated. 

Moto Not Working Sample.pcapng

[Martin Lesund]

Hi Jmuralinux,

Does it work better with nRF Connect?

 Seems like there is an issue with the Moto E4. I have two proposals to you:

1.  Try to refresh the device cache (use nRF Connect to check if it works, then try it in the app) 

2. Change the phone?

[jmuralinux]

The issue that I noticed is with both nRFConnect and nRFtoolbox apps. i will try the device cache option and update. 

Our solution with this product is targeted for a wide audience and we do not control what phones the customers can use and would like to understand if this is a limitation on Moto E4 itself or Android or Nordic (soft device). If there is a work around possible, we would like to try that as well. Our own app and the nRF apps work fine with quite few other phones that we tested with (as mentioned in my OP).

[Martin Lesund]

- What SDK version and Softdevice version are you using?

- Have you seen this thread? (It may be of help)

[jmuralinux]

We are using s140_nrf52_6.0.0 Soft device and not using SDK.

I read the thread earlier but do not really understand what handle is to be set. We are setting the start_on_notify_cccd_handle to BLE_GATT_HANDLE_INVALID and calling the sd_ble_gap_ppcp_get. Any inputs on which handle to be used here?

Thanks!

[Martin Lesund]

If you are not using our SDK:

- Then you have to run a sd_ble_gap_conn_param_update() to trigger a parameter update from the peripheral. If you have used sd_ble_gap_ppcp_set() before that, then you can use NULL for *p_conn_params for  sd_ble_gap_conn_param_update().