Generic Attribute Profile (GATT)

Generic Attribute Profile (GATT) . More...

Topics
	GATT Client APIs
	GATT Server APIs

Data Structures
struct	bt_gatt_attr
	GATT Attribute. More...
struct	bt_gatt_service_static
	GATT Service structure. More...
struct	bt_gatt_service
	GATT Service structure. More...
struct	bt_gatt_service_val
	Service Attribute Value. More...
struct	bt_gatt_include
	Include Attribute Value. More...
struct	bt_gatt_cb
	GATT callback structure. More...
struct	bt_gatt_authorization_cb
	GATT authorization callback structure. More...
struct	bt_gatt_chrc
	Characteristic Attribute Value. More...
struct	bt_gatt_cep
	Characteristic Extended Properties Attribute Value. More...
struct	bt_gatt_ccc
	Client Characteristic Configuration Attribute Value. More...
struct	bt_gatt_scc
	Server Characteristic Configuration Attribute Value. More...
struct	bt_gatt_cpf
	GATT Characteristic Presentation Format Attribute Value. More...

Macros
#define	BT_GATT_ERR(_att_err)
	Construct error return value for attribute read and write callbacks.
#define	BT_GATT_CHRC_BROADCAST   0x01
	Characteristic Properties Bit field values.
#define	BT_GATT_CHRC_READ   0x02
	Characteristic read property.
#define	BT_GATT_CHRC_WRITE_WITHOUT_RESP   0x04
	Characteristic write without response property.
#define	BT_GATT_CHRC_WRITE   0x08
	Characteristic write with response property.
#define	BT_GATT_CHRC_NOTIFY   0x10
	Characteristic notify property.
#define	BT_GATT_CHRC_INDICATE   0x20
	Characteristic indicate property.
#define	BT_GATT_CHRC_AUTH   0x40
	Characteristic Authenticated Signed Writes property.
#define	BT_GATT_CHRC_EXT_PROP   0x80
	Characteristic Extended Properties property.
#define	BT_GATT_CEP_RELIABLE_WRITE   0x0001
	Characteristic Extended Properties Bit field values.
#define	BT_GATT_CEP_WRITABLE_AUX   0x0002
#define	BT_GATT_CCC_NOTIFY   0x0001
	Client Characteristic Configuration Values.
#define	BT_GATT_CCC_INDICATE   0x0002
	Client Characteristic Configuration Indication.
#define	BT_GATT_SCC_BROADCAST   0x0001
	Server Characteristic Configuration Values.

Typedefs
typedef ssize_t(*	bt_gatt_attr_read_func_t) (struct bt_conn *conn, const struct bt_gatt_attr *attr, void *buf, uint16_t len, uint16_t offset)
	Attribute read callback.
typedef ssize_t(*	bt_gatt_attr_write_func_t) (struct bt_conn *conn, const struct bt_gatt_attr *attr, const void *buf, uint16_t len, uint16_t offset, uint8_t flags)
	Attribute Value write implementation.

Enumerations
enum	bt_gatt_perm {   BT_GATT_PERM_NONE = 0 , BT_GATT_PERM_READ = BIT(0) , BT_GATT_PERM_WRITE = BIT(1) , BT_GATT_PERM_READ_ENCRYPT = BIT(2) ,   BT_GATT_PERM_WRITE_ENCRYPT = BIT(3) , BT_GATT_PERM_READ_AUTHEN = BIT(4) , BT_GATT_PERM_WRITE_AUTHEN = BIT(5) , BT_GATT_PERM_PREPARE_WRITE = BIT(6) ,   BT_GATT_PERM_READ_LESC = BIT(7) , BT_GATT_PERM_WRITE_LESC = BIT(8) }
	GATT attribute permission bit field values. More...
enum	{ BT_GATT_WRITE_FLAG_PREPARE = BIT(0) , BT_GATT_WRITE_FLAG_CMD = BIT(1) , BT_GATT_WRITE_FLAG_EXECUTE = BIT(2) }
	GATT attribute write flags. More...

Detailed Description

Generic Attribute Profile (GATT) .

Macro Definition Documentation

BT_GATT_CCC_INDICATE

#define BT_GATT_CCC_INDICATE   0x0002

#include <zephyr/bluetooth/gatt.h>

Client Characteristic Configuration Indication.

If set, changes to Characteristic Value shall be indicated.

BT_GATT_CCC_NOTIFY

#define BT_GATT_CCC_NOTIFY   0x0001

#include <zephyr/bluetooth/gatt.h>

Client Characteristic Configuration Values.

Client Characteristic Configuration Notification.

If set, changes to Characteristic Value shall be notified.

BT_GATT_CEP_RELIABLE_WRITE

#define BT_GATT_CEP_RELIABLE_WRITE   0x0001

#include <zephyr/bluetooth/gatt.h>

Characteristic Extended Properties Bit field values.

BT_GATT_CEP_WRITABLE_AUX

#define BT_GATT_CEP_WRITABLE_AUX   0x0002

#include <zephyr/bluetooth/gatt.h>

BT_GATT_CHRC_AUTH

#define BT_GATT_CHRC_AUTH   0x40

#include <zephyr/bluetooth/gatt.h>

Characteristic Authenticated Signed Writes property.

If set, permits signed writes to the Characteristic Value.

BT_GATT_CHRC_BROADCAST

#define BT_GATT_CHRC_BROADCAST   0x01

#include <zephyr/bluetooth/gatt.h>

Characteristic Properties Bit field values.

Characteristic broadcast property.

If set, permits broadcasts of the Characteristic Value using Server Characteristic Configuration Descriptor.

BT_GATT_CHRC_EXT_PROP

#define BT_GATT_CHRC_EXT_PROP   0x80

#include <zephyr/bluetooth/gatt.h>

Characteristic Extended Properties property.

If set, additional characteristic properties are defined in the Characteristic Extended Properties Descriptor.

BT_GATT_CHRC_INDICATE

#define BT_GATT_CHRC_INDICATE   0x20

#include <zephyr/bluetooth/gatt.h>

Characteristic indicate property.

If set, permits indications of a Characteristic Value with acknowledgment.

BT_GATT_CHRC_NOTIFY

#define BT_GATT_CHRC_NOTIFY   0x10

#include <zephyr/bluetooth/gatt.h>

Characteristic notify property.

If set, permits notifications of a Characteristic Value without acknowledgment.

BT_GATT_CHRC_READ

#define BT_GATT_CHRC_READ   0x02

#include <zephyr/bluetooth/gatt.h>

Characteristic read property.

If set, permits reads of the Characteristic Value.

BT_GATT_CHRC_WRITE

#define BT_GATT_CHRC_WRITE   0x08

#include <zephyr/bluetooth/gatt.h>

Characteristic write with response property.

If set, permits write of the Characteristic Value with response.

BT_GATT_CHRC_WRITE_WITHOUT_RESP

#define BT_GATT_CHRC_WRITE_WITHOUT_RESP   0x04

#include <zephyr/bluetooth/gatt.h>

Characteristic write without response property.

If set, permits write of the Characteristic Value without response.

BT_GATT_ERR

#define BT_GATT_ERR

(

_att_err

)

#include <zephyr/bluetooth/gatt.h>

Value:

(-(_att_err))

Construct error return value for attribute read and write callbacks.

Parameters

_att_err

ATT error code

Returns

Appropriate error code for the attribute callbacks.

BT_GATT_SCC_BROADCAST

#define BT_GATT_SCC_BROADCAST   0x0001

#include <zephyr/bluetooth/gatt.h>

Server Characteristic Configuration Values.

Server Characteristic Configuration Broadcast

If set, the characteristic value shall be broadcast in the advertising data when the server is advertising.

Typedef Documentation

bt_gatt_attr_read_func_t

typedef ssize_t(* bt_gatt_attr_read_func_t) (struct bt_conn *conn, const struct bt_gatt_attr *attr, void *buf, uint16_t len, uint16_t offset)

#include <zephyr/bluetooth/gatt.h>

Attribute read callback.

This is the type of the bt_gatt_attr.read() method.

This function may safely assume the Attribute Permissions are satisfied for this read. Callers are responsible for this.

Callers may set conn to emulate a GATT client read, or leave it NULL for local reads.

Note

GATT server relies on this method to handle read operations from remote GATT clients. But this method is not reserved for the GATT server. E.g. You can lookup attributes in the local ATT database and invoke this method.

The GATT server propagates the return value from this method back to the remote client.

Parameters

conn	The connection that is requesting to read. NULL if local.
attr	The attribute that's being read
buf	Buffer to place the read result in
len	Length of data to read
offset	Offset to start reading from

Returns

Number of bytes read, or in case of an error BT_GATT_ERR() with a specific BT_ATT_ERR_* error code.

bt_gatt_attr_write_func_t

typedef ssize_t(* bt_gatt_attr_write_func_t) (struct bt_conn *conn, const struct bt_gatt_attr *attr, const void *buf, uint16_t len, uint16_t offset, uint8_t flags)

#include <zephyr/bluetooth/gatt.h>

Attribute Value write implementation.

This is the type of the bt_gatt_attr.write() method.

This function may safely assume the Attribute Permissions are satisfied for this write. Callers are responsible for this.

Callers may set conn to emulate a GATT client write, or leave it NULL for local writes.

If flags contains BT_GATT_WRITE_FLAG_PREPARE, then the method shall not perform a write, but instead only check if the write is authorized and return an error code if not.

Attribute Value write implementations can and often do have side effects besides potentially storing the value. E.g. togging an LED.

Note

GATT server relies on this method to handle write operations from remote GATT clients. But this method is not reserved for the GATT server. E.g. You can lookup attributes in the local ATT database and invoke this method.

The GATT server propagates the return value from this method back to the remote client.

Parameters

conn	The connection that is requesting to write
attr	The attribute that's being written
buf	Buffer with the data to write
len	Number of bytes in the buffer
offset	Offset to start writing from
flags	Flags (BT_GATT_WRITE_FLAG_*)

Returns

Number of bytes written, or in case of an error BT_GATT_ERR() with a specific BT_ATT_ERR_* error code.

Enumeration Type Documentation

anonymous enum

anonymous enum

#include <zephyr/bluetooth/gatt.h>

GATT attribute write flags.

Enumerator
BT_GATT_WRITE_FLAG_PREPARE	Attribute prepare write flag. If set, write callback should only check if the device is authorized but no data shall be written.
BT_GATT_WRITE_FLAG_CMD	Attribute write command flag. If set, indicates that write operation is a command (Write without response) which doesn't generate any response.
BT_GATT_WRITE_FLAG_EXECUTE	Attribute write execute flag. If set, indicates that write operation is a execute, which indicates the end of a long write, and will come after 1 or more BT_GATT_WRITE_FLAG_PREPARE.

bt_gatt_perm

enum bt_gatt_perm

#include <zephyr/bluetooth/gatt.h>

GATT attribute permission bit field values.

Enumerator
BT_GATT_PERM_NONE	No operations supported, e.g. for notify-only
BT_GATT_PERM_READ	Attribute read permission.
BT_GATT_PERM_WRITE	Attribute write permission.
BT_GATT_PERM_READ_ENCRYPT	Attribute read permission with encryption. If set, requires encryption for read access.
BT_GATT_PERM_WRITE_ENCRYPT	Attribute write permission with encryption. If set, requires encryption for write access.
BT_GATT_PERM_READ_AUTHEN	Attribute read permission with authentication. If set, requires encryption using authenticated link-key for read access.
BT_GATT_PERM_WRITE_AUTHEN	Attribute write permission with authentication. If set, requires encryption using authenticated link-key for write access.
BT_GATT_PERM_PREPARE_WRITE	Attribute prepare write permission. If set, allows prepare writes with use of BT_GATT_WRITE_FLAG_PREPARE passed to write callback.
BT_GATT_PERM_READ_LESC	Attribute read permission with LE Secure Connection encryption. If set, requires that LE Secure Connections is used for read access.
BT_GATT_PERM_WRITE_LESC	Attribute write permission with LE Secure Connection encryption. If set, requires that LE Secure Connections is used for write access.