User's Manual

the configuration of a local characteristic, command “SHR” should be used to
retrieve such information.
This command is effective with or without an active link. Reading value of a
characteristic locally is always permitted regardless of characteristic property.
Characteristic property is only used for remote access. The value returned is
retrieved from local device and equal to what is written at most recent time.
Example: SUR,2A19 // Read the local value of characteristic with
// UUID 0x2A19
3.3.3.13 SUW
According to command interpolation method described in section 3.3.3.1, command
“SUW” writes content of characteristic in server service to local device by
addressing its UUID.
This command takes two parameters. The first parameter is hex value of the UUID of
a characteristic. The UUID could be either 16-bit short UUID for public
characteristic, or 128bit long UUID for private characteristic. The second parameter
is the content to be written to the characteristic. The format of each public
characteristic is defined in Bluetooth SIG specifications. The user defines the format
of each private characteristic.
This command is effective only if the UUID is valid in server service. Characteristic
in server service is always writable regardless of its property. Characteristic
property is only for remote access. The configuration of a characteristic, which
starts or stops notification/indication, is usually set remotely. Therefore, command
“SUW” could not be used to modify the configuration of local characteristic. In the
exceptional case that such configuration has to be modified, command “SHW”
should be considered.
When Buffered Read feature (See section 3.2.1.12 for command “SR”) is not enabled,
RN4020 requests content of a characteristic from the host MCU, when receiving
read request from the remote device. The host MCU needs to use command “SHW”
or “SUW” to write the content and therefore responds to the request.
When command “SUW” is issued to change the local content of characteristic, a
notification or indication might be send to remote device, if following conditions are
met:
 An active connection exists
 Remote device support the corresponding service and characteristic as client
role
 Property of corresponding characteristic supports notification or indication