BLE enable notification on nRF52833

[Katie Newell]

Hi all,

I am developing BLE firmware to send and receive data between the development kit PCA10100 and nRFConnect App Desktop. 

I'd like to notify the client (the App) that data changed and update the data value. Following this tutorial, it seems that the server (my dev board) can only notify if the client enable notification. Is my understanding correct? When the client enable the notification, the server gets a notification enabled and that's when it can update data. I've implemented this using sd_ble_gatts_hvx and it is working ok for me. 

I'd like to notify/update data to the client without the client enabling the notification. Is this possible?

Many thanks 

Regards

[Hung Bui]

Hi Katie, 

It's designed by spec that the CCCD (Client Characteristic Configuration Descriptor) has to be enabled before the server can send the notification to the client. You can have a look here.

It's possible to skip that only if you have paired to the peer device. When you re-connect you can reuse the previous value of CCCD to send notification right away without waiting for the client to enable CCCD. This feature is already supported in most of our BLE example (that use peer manager library)

[Katie Newell]

Hi Hung, 

Many thanks for your reply. 

Your explanation is clear, thank you. Could you please re-post the link you attached above? I am getting server error when I open it. 

Many thanks

Kind regards

[Hung Bui]

Please try again with this link: https://infocenter.nordicsemi.com/topic/com.nordic.infocenter.s132.api.v7.2.0/group___b_l_e___g_a_t_t_s___h_v_n___m_s_c.html?cp=4_7_3_1_2_4_3_5

[Katie Newell]

This works

Many thanks