Can't SoftDevice recognize cccd?

[JoonDong]

I coded following

BLE_GAP_CONN_SEC_MODE_SET_NO_ACCESS(&cccd_md.read_perm);

BLE_GAP_CONN_SEC_MODE_SET_NO_ACCESS(&cccd_md.write_perm);

char_md.char_props.notify = 1;

char_md.p_cccd_md = &cccd;

and deleted everything that check m_nus.is_notification_enabled.

Then notification operation works well.

Is the cccd just one of attributes?

Is enabling or disabling notification done manually by checking m_nus.is_notification_enabled(reflected cccd value)?

[FormerMember]

The purpose of the code knowing if the notifications are enabled or not, is for the application to know its current state. If trying to transmit a notification when notifications aren't enabled, sd_ble_gatts_hvx(..) will return NRF_ERROR_INVALID_STATE. The example ble_app_hrs is an example that doesn't know its current state: As long as there is a connection, it will try to update the heart rate measurement values.

[JoonDong]

So how can I change cccd value in server altough it is designated for client originally ?

[FormerMember]

If a server is able to enable notifications by itself, it will break the Bluetooth Core Specification. Therefore, I doubt that it is possible to do so.

[JoonDong]

So why does sd_ble_gatts_value_set() exist?

[FormerMember]

sd_ble_gatts_value_set() is used to set the value of the attribute. Notification/CCCD is a part of the properties of the attribute.

[JoonDong]

But I heard descriptor(including CCCD) is also attribute, isn't it?