RN4870/71 PICtail™/PICtail Plus Daughter Board User’s Guide
DS50002547A-page 54
2016 Microchip Technology Inc.
, the GATT client can access the characteristics in the GATT
server in the Peripheral device. When connected, the GATT client reads the GATT
server service and characteristic UUIDs. The characteristic values can be accessed by
the GATT client using Write, Read, Indication and Notifications.
Write-REQ enables the GATT client to update characteristic values on the Peripheral's
GATT server. The write requests can be performed using RN4870
CHW
and
CUW
com-
mands. Refer to
Section 3.6 “Accessing GATT Service Using UART Commands
for more information on GATT characteristic access com-
mands.
A Write-CMD message performs an unacknowledged write from a GATT client to the
GATT server. This is allowed for Transparent UART Write procedure on the RN4870
when
SR,0100
command is used.
A GATT client sends Read-REQ read a characteristic value on the Peripheral's GATT
server. The read requests can be performed using RN4870
CHR
and
CUR
commands.
Notifications and Indications are unsolicited updates sent from the GATT server to the
GATT client. The GATT client must enable the Notification and Indication on a charac-
teristic to receive the updates. On the RN487x module, this is done by using the
CUW
or
CHW
command to write non-zero value to the Notification Characteristic. When
RN487x in Client mode receives a notification, the
%WC,hhhh,ddddddd%
message is
returned on UART in Command mode.
FIGURE C-1:
GATT SERVICE IN
RN4870
[GAP Peripheral, GATT Server]
GATT Server Service
Public Service 16-bit UUID
Characteristic 16-bit UUID
Properties & Descriptors
Characteristic 16-bit UUID
Properties & Descriptors
Characteristic 16-bit UUID
Properties & Descriptors
Private Service 128-bit UUID
Characteristic 128-bit UUID
Properties & Descriptors
Characteristic 16-bit UUID
Properties & Descriptors
Characteristic 128-bit UUID
Properties & Descriptors
BTLE Device
[GAP Central, GATT Client]
Central-Client devices
include the following:
x
SmartPhone
x
Host PC
x
Tablet
x
RN4020 module
x
RN4870 module
x
Other BTLE device
GATT Client Write-
5(4
GATT Client Read-
5(4
GATT Notification
GATT Indication
ACK-Write-REQ
Read-RESP
GATT Client Write-
&0'
ACK-Indication
