Can't SoftDevice recognize cccd?

RE: Can't SoftDevice recognize cccd?

JoonDong — Tue, 14 Feb 2017 01:25:47 GMT

Thank you. It's very useful.

RE: Can't SoftDevice recognize cccd?

FormerMember — Mon, 13 Feb 2017 20:55:00 GMT

Yes, a CCCD is an attribute, but because setting it manually breaks the spec, it is not possible to do so. This thread explains it a little more thoroughly.

RE: Can't SoftDevice recognize cccd?

JoonDong — Mon, 13 Feb 2017 11:02:27 GMT

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

RE: Can't SoftDevice recognize cccd?

FormerMember — Mon, 13 Feb 2017 09:50:00 GMT

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.

RE: Can't SoftDevice recognize cccd?

JoonDong — Fri, 10 Feb 2017 14:40:06 GMT

So why does sd_ble_gatts_value_set() exist?

RE: Can't SoftDevice recognize cccd?

FormerMember — Fri, 10 Feb 2017 14:12:16 GMT

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.

RE: Can't SoftDevice recognize cccd?

JoonDong — Fri, 10 Feb 2017 13:51:13 GMT

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

RE: Can't SoftDevice recognize cccd?

FormerMember — Fri, 10 Feb 2017 12:44:43 GMT

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.