org.bluez.GattCharacteristic - Man Page
BlueZ D-Bus GattCharacteristic API documentation
Description
GATT local/server and remote/client characteristic attribute representation share the same high-level D-Bus API.
Local/Server refers to GATT based characteristics exported by a plugin or an external application.
Remote/Client refers to GATT characteristics exported by the peer.
Interface
Client
- Service
org.bluez
- Interface
org.bluez.GattCharacteristic1
- Object path
[variable prefix]/{hci0,hci1,...}/dev_XX_XX_XX_XX_XX_XX/serviceXX/charYYYY
Server
- Service
unique name
- Interface
org.bluez.GattCharacteristic1
- Object path
freely definable
Methods
array{byte} ReadValue(dict options)
Issues a request to read the value of the characteristic and returns the value if the operation was successful.
Possible options:
- uint16_t offset
Read start offset in bytes.
- uint16_t mtu (server only)
Exchange MTU in bytes.
- object device (server only)
Device object.
Possible Errors:
- org.bluez.Error.Failed
Possible values: string 0x80 - 0x9f
org.bluez.Error.InProgress
org.bluez.Error.NotPermitted
org.bluez.Error.NotAuthorized
org.bluez.Error.InvalidOffset
org.bluez.Error.NotSupported
void WriteValue(array{byte} value, dict options)
Issues a request to write the value of the characteristic.
Possible options:
- uint16 offset
Write start offset in bytes.
- string type
Possible values:
- "command"
Use Write without response procedure.
- "request"
Use Write with response procedure.
- "reliable"
Use Reliable Write procedure.
- uint16 mtu
Exchanged MTU (Server only).
- object device
Device path (Server only).
- string link
Link type (Server only).
Possible values:
"BR/EDR"
"LE"
- boolean prepare-authorize
True if prepare authorization request.
Possible Errors:
- org.bluez.Error.Failed
Possible values: string 0x80 - 0x9f
org.bluez.Error.InProgress
org.bluez.Error.NotPermitted
org.bluez.Error.InvalidValueLength
org.bluez.Error.NotAuthorized
org.bluez.Error.NotSupported
fd, uint16 AcquireWrite(dict options) [optional]
Acquire file descriptor and MTU for writing. Only sockets are supported. Usage of WriteValue will be locked causing it to return NotPermitted error.
For server the MTU returned shall be equal or smaller than the negotiated MTU.
For client it only works with characteristic that has WriteAcquired property which relies on write-without-response Flag.
To release the lock the client shall close the file descriptor, a HUP is generated in case the device is disconnected.
Note: the MTU can only be negotiated once and is symmetric therefore this method may be delayed in order to have the exchange MTU completed, because of that the file descriptor is closed during reconnections as the MTU has to be renegotiated.
Possible options:
- object device
Object Device (Server only).
- uint16 mtu
Exchanged MTU (Server only).
- string link
Link type (Server only).
Possible values:
"BR/EDR"
"LE"
Possible Errors:
org.bluez.Error.Failed
org.bluez.Error.NotSupported
fd, uint16 AcquireNotify(dict options) [optional]
Acquire file descriptor and MTU for notify. Only sockets are support.
Usage of StartNotify will be locked causing it to return org.bluez.Error.NotPermitted.
For server the MTU returned shall be equal or smaller than the negotiated MTU.
Only works with characteristic that has NotifyAcquired property which relies on "notify" Flag and no other client have called StartNotify().
Notification are enabled during this procedure so StartNotify() shall not be called, any notification will be dispatched via file descriptor therefore the Value property is not affected during the time where notify has been acquired.
To release the lock the client shall close the file descriptor, a HUP is generated in case the device is disconnected.
Note: the MTU can only be negotiated once and is symmetric therefore this method may be delayed in order to have the exchange MTU completed, because of that the file descriptor is closed during reconnections as the MTU has to be renegotiated.
Possible options:
- object device
Object Device (Server only).
- uint16 mtu
Exchanged MTU (Server only).
- string link
Link type (Server only).
Possible values:
"BR/EDR"
"LE"
Possible Errors:
org.bluez.Error.Failed
org.bluez.Error.NotSupported
org.bluez.Error.NotPermitted
void StartNotify()
Starts a notification session from this characteristic if it supports value notifications or indications.
Possible Errors:
org.bluez.Error.Failed
org.bluez.Error.NotPermitted
org.bluez.Error.InProgress
org.bluez.Error.NotConnected
org.bluez.Error.NotSupported
void StopNotify()
Stops or cancel session previously created by StartNotify().
Note that notifications from a characteristic are shared between sessions thus calling StopNotify will release a single session.
Possible Errors:
org.bluez.Error.Failed
void Confirm() [noreply, optional] (Server only)
Confirms value was received.
Possible Errors:
org.bluez.Error.Failed
Properties
string UUID [read-only]
128-bit characteristic UUID.
object Service [read-only]
Object path of the GATT service the characteristic belongs to.
array{byte} Value [read-only, optional]
The cached value of the characteristic. This property gets updated only after a successful read request and when a notification or indication is received, upon which a PropertiesChanged signal will be emitted.
boolean WriteAcquired [read-only, optional]
True, if this characteristic has been acquired by any client using AcquireWrite.
For client properties is ommited in case 'write-without-response' flag is not set.
For server the presence of this property indicates that AcquireWrite is supported.
boolean NotifyAcquired [read-only, optional]
True, if this characteristic has been acquired by any client using AcquireNotify.
For client this properties is ommited in case 'notify' flag is not set.
For server the presence of this property indicates that AcquireNotify is supported.
boolean Notifying [read-only, optional]
True, if notifications or indications on this characteristic are currently enabled.
array{string} Flags [read-only]
Defines how the characteristic value can be used. See Core spec "Table 3.5: Characteristic Properties bit field", and "Table 3.8: Characteristic Extended Properties bit field".
The "x-notify" and "x-indicate" flags restrict access to notifications and indications by imposing write restrictions on a characteristic's client characteristic configuration descriptor.
Possible values:
"broadcast"
"read"
"write-without-response"
"write"
"notify"
"indicate"
"authenticated-signed-writes"
"extended-properties"
"reliable-write"
"writable-auxiliaries"
"encrypt-read"
"encrypt-write"
"encrypt-notify" (Server only)
"encrypt-indicate" (Server only)
"encrypt-authenticated-read"
"encrypt-authenticated-write"
"encrypt-authenticated-notify" (Server only)
"encrypt-authenticated-indicate" (Server only)
"secure-read" (Server only)
"secure-write" (Server only)
"secure-notify" (Server only)
"secure-indicate" (Server only)
"authorize"
uint16 Handle [read-only] (Client Only)
Characteristic handle.
uint16 Handle [read-write, optional] (Server Only)
Characteristic handle. When available in the server it would attempt to use to allocate into the database which may fail, to auto allocate the value 0x0000 shall be used which will cause the allocated handle to be set once registered.
uint16 MTU [read-only]
Characteristic MTU, this is valid both for ReadValue() and WriteValue() but either method can use long procedures when supported.