UART example in SDK 13.0.0 will not connect

[gnf]

The UART example in examples\ble_peripheral\ble_app_uart will not connect with SDK 13.0.0. This example was running just fine with v11.0.0 (Softdevice S132 v2.0.0) and v12.2.0 (Softdevice S132 v3.0.0) but now when I am trying to upgrade to SDK 13.0.0 (Softdevice S132 v4.0.2) I can not get a connection.

I have been trying the apps "nRF Connect" and "nRF UART v2.0" without success. This was no problem with v11 and v12.

I downloaded the SDK v13.0.0_04a0bfd from here: developer.nordicsemi.com/.../

The evaluation board I'm using is a PCA10040 V1.1.0

Where should I start looking?

Edit: The debug log looks like this (with settings #define NRF_LOG_DEFAULT_LEVEL 4 and #define NRF_LOG_BACKEND_SERIAL_USES_UART 1):

UART Start!
                                                               
SDH:DEBUG:RAM start at 0x200025f8.

                                      
                                                                            
UART Start!
                                                               
APP:INFO:UART Start!
                                                      
nrf_ble_gatt:DEBUG:Requesting to update ATT MTU to 64 bytes on connection 0x0.

nrf_ble_gatt:DEBUG:Requesting to update data length to 162 on connection 0x0.

APP:INFO:Connected
                                                        
APP:INFO:Disconnected
                                                     
nrf_ble_gatt:DEBUG:Requesting to update ATT MTU to 64 bytes on connection 0x0.

nrf_ble_gatt:DEBUG:Requesting to update data length to 162 on connection 0x0.

APP:INFO:Connected
                                                        
nrf_ble_gatt:DEBUG:ATT MTU updated to 64 bytes on connection 0x0 (response).

APP:INFO:Data len is set to 0x3D(61)
                                      
APP:DEBUG:ATT MTU exchange completed. central 0x9e peripheral 0x40
        
APP:INFO:Disconnected
                                                     
nrf_ble_gatt:DEBUG:Requesting to update ATT MTU to 64 bytes on connection 0x0.

nrf_ble_gatt:DEBUG:Requesting to update data length to 162 on connection 0x0.

APP:INFO:Connected
                                                        
APP:INFO:Disconnected
                                                     
nrf_ble_gatt:DEBUG:Requesting to update ATT MTU to 64 bytes on connection 0x0.

nrf_ble_gatt:DEBUG:Requesting to update data length to 162 on connection 0x0.

APP:INFO:Connected
                                                        
APP:INFO:Disconnected

[Hung Bui]

Hi GNF,

Could you let me know which phone are you using ?

It seems that the phone doesn't support Bluetooth 4.2 features and when the nRF52 request it would just simply disconnect.

My suggestion is to disable request to extend ATT MTU and data length which is handled by the experimental GATT module.

Please try to comment out gatt_init(); in main() and nrf_ble_gatt_on_ble_evt() in ble_evt_dispatch().

[gnf]

Thank you! When commenting out the lines you suggest it works.

I have not yet understood what the experimental GATT module does. Is this new for ver 13 of the SDK?

Anyway, I have tested the following phones:

• Sony E6553, Android 7.0: Does not work without the fix.
• Sony E6653, Android 7.0: Does not work without the fix.
• Google Nexus 5X, Android 7.1.1: Works!
• Iphone (model unclear): Works!

By the way, the app I was using on the Android devices was nRF Connect version 4.11.0

[Hung Bui]

I just checked the Sony E6553 spec stated that it only supports Bluetooth 4.1, most likely it's the reason why it disconnects.