When will I need to use ble_gatts_char_md_t, ble_gatts_attr_md_t... etc, and why?

[Mitch996]

Hello, I find these structs:

ble_gatts_attr_md_t ble_gatts_char_md_t

show up quite often in example projects. My qeustions are:

What are these? And when will I be needing them? For example, adding my very own, gatt based services?

[Jørgen Holmefjord]

Hi,

I have copied the description of these structures from BLE Characteristics, a beginner's tutorial:

ble_gatts_attr_md_t attr_md, The Attribute Metadata: This is a structure holding permissions and authorization levels required by characteristic value attributes. It also holds information on whether or not the characteristic value is of variable length and where in memory it is stored.

ble_gatts_char_md_t char_md, The Characteristic Metadata: This is a structure holding the value properties of the characteristic value. It also holds metadata of the CCCD and possibly other kinds of descriptors.

More details about the content of the structures can be found in ble_gatts_attr_md_t Struct Reference and ble_gatts_char_md_t Struct Reference.

I recomment you to go through the above mentioned tutorial, and the other BLE tutorials, to learn more about creating BLE applications.

Best regards,

Jørgen