SWRU270
Page 19 of 28
Figure 26
The value should be “03” in each notification, since it is copied from the value of the third characteristic
in the profile (which has a default value of 3). The third characteristic has write-only properties, and
therefore can be changed. By following the procedure from section 4.3.4, the handle of the third
characteristic can be found to be 0x0017. By following the procedure from section 4.3.2, a new value can
be written to handle 0x0017. Once this is done, the value of the fourth characteristic will change. This
new value is reflected in the incoming notification messages.
Figure 27
4.4 Using the Simple Keys GATT Profile
The simple keys profile on the keyfob allows the device to send notifications of key presses and releases to
a central device. The UUID of the simple keys data characteristic value is 0xFFE1.
Using the same discovery process as before with the “Discover Characteristic by UUID” command, it can
be determined that the handle of the simple keys data is 0x001F. Like the fourth characteristic value in
the simple GATT profile, the simple keys data is a “configurable” characteristic, in that the client device
can configure the server to send notifications of the characteristic value. The handle immediately
following the characteristic value is the “characteristic configuration”.
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