Getting Started With EZ-
BLE™ PRoC™ Module
www.cypress.com
Document No.: 001-96841 Rev. **
10
Figure 10
shows the services and characteristics
implemented in the peripheral.
G e n e r i c At t r i b u t e P r o f i l e ( G AT T )
GATT defines the ways in which the attributes can be
found and used. GATT operates in one of two roles:
GATT client:
The device that requests the data.
GATT server:
The device that provides the data.
Figure 9
shows the client-server architecture in the GATT
layer.
Figure 9. Client-Server Architectures
Client
Server
Service
Char.
Service
Char.
Service
Char.
Requests
Responses
Figure 10
shows an example in which a smartphone is
configured as the GATT client (wants data) and a heart
rate sensor that is configured as the GATT server (has
data).
G e n e r i c A c c e s s P r o f i l e ( G AP )
The GAP layer provides the device-specific information:
device address, device name, and how it can be
discovered and connected.
Profile:
This specification defines how devices connect to
each other to find and use services. It describes the type
of application and general expected behavior of that
device.
Figure 10
shows an example of a Heart rate
monitor Profile.
The GAP layer operates in one of four roles:
Broadcaster:
This is a non-connectable advertising
role that is used to broadcast its data, but cannot form
BLE connections. A typical example of a GAP
broadcaster is iBeacon.
Observer:
This is a listening role that scans for
advertisements. It is capable of connections but
cannot initiate one. A typical example of a GAP
observer is a packet sniffer.
Peripheral:
This is a connectable advertising role that
operates as a slave after a connection is established.
For example, a heart-rate sensor reporting the
measured heart-rate to a remote device operates as a
GAP peripheral.
Central:
This is a GAP role that scans for
advertisements and initiates connections. It operates
as a master after a connection is established. For
example, a mobile device retrieving the heart-rate
measurement from a peripheral heart-rate sensor
operates as a GAP central.
Figure 10
shows an example where a smartphone in
which the heart rate app operates as a GAP central and
the heart-rate sensor operates as a GAP peripheral.
