Hardware Reference
In-Depth Information
Table 4-8. Service changed characteristic value
Handle
Type
Permissions
Value
Value length
UUID
service changed
None
Affected handle range
4
0xNNNN
A client must enable indications on the corresponding CCCD for this characteristic
before doing anything else, so that it can become aware of any changes on the server's
attribute structure.
If the server suffers a structural change in attribute layout, it will then immediately send
a handle value indication to the client and wait for the corresponding confirmation. In
this way, it can be sure that the client understands that cached attribute handles in that
range might no longer be valid. If the attributes change outside the lifetime of a con‐
nection with a bonded device, the server will send the indication right after the con‐
nection is set up, so that the client has a chance to rediscover the affected area.
