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Attribute Protocol (ATT)¶

API Reference¶

group bt_att

Attribute Protocol (ATT)

Defines

BT_ATT_ERR_SUCCESS¶: The ATT operation was successful.

BT_ATT_ERR_INVALID_HANDLE¶: The attribute handle given was not valid on the server.

BT_ATT_ERR_READ_NOT_PERMITTED¶: The attribute cannot be read.

BT_ATT_ERR_WRITE_NOT_PERMITTED¶: The attribute cannot be written.

BT_ATT_ERR_INVALID_PDU¶: The attribute PDU was invalid.

BT_ATT_ERR_AUTHENTICATION¶: The attribute requires authentication before it can be read or written.

BT_ATT_ERR_NOT_SUPPORTED¶: The ATT Server does not support the request received from the client.

BT_ATT_ERR_INVALID_OFFSET¶: Offset specified was past the end of the attribute.

BT_ATT_ERR_AUTHORIZATION¶: The attribute requires authorization before it can be read or written.

BT_ATT_ERR_PREPARE_QUEUE_FULL¶: Too many prepare writes have been queued.

BT_ATT_ERR_ATTRIBUTE_NOT_FOUND¶: No attribute found within the given attribute handle range.

BT_ATT_ERR_ATTRIBUTE_NOT_LONG¶: The attribute cannot be read using the ATT_READ_BLOB_REQ PDU.

BT_ATT_ERR_ENCRYPTION_KEY_SIZE¶: The Encryption Key Size used for encrypting this link is too short.

BT_ATT_ERR_INVALID_ATTRIBUTE_LEN¶: The attribute value length is invalid for the operation.

BT_ATT_ERR_UNLIKELY¶

The attribute request that was requested has encountered an error that was unlikely.

The attribute request could therefore not be completed as requested

BT_ATT_ERR_INSUFFICIENT_ENCRYPTION¶: The attribute requires encryption before it can be read or written.

BT_ATT_ERR_UNSUPPORTED_GROUP_TYPE¶

The attribute type is not a supported grouping attribute.

The attribute type is not a supported grouping attribute as defined by a higher layer specification.

BT_ATT_ERR_INSUFFICIENT_RESOURCES¶: Insufficient Resources to complete the request.

BT_ATT_ERR_DB_OUT_OF_SYNC¶: The server requests the client to rediscover the database.

BT_ATT_ERR_VALUE_NOT_ALLOWED¶: The attribute parameter value was not allowed.

BT_ATT_ERR_WRITE_REQ_REJECTED¶: Write Request Rejected.

BT_ATT_ERR_CCC_IMPROPER_CONF¶: Client Characteristic Configuration Descriptor Improperly Configured.

BT_ATT_ERR_PROCEDURE_IN_PROGRESS¶: Procedure Already in Progress.

BT_ATT_ERR_OUT_OF_RANGE¶: Out of Range.

BT_ATT_MAX_ATTRIBUTE_LEN¶

BT_ATT_FIRST_ATTRIBUTE_HANDLE¶

BT_ATT_FIRST_ATTTRIBUTE_HANDLE¶

BT_ATT_LAST_ATTRIBUTE_HANDLE¶

BT_ATT_LAST_ATTTRIBUTE_HANDLE¶

Enums

enum bt_att_chan_opt¶

ATT channel option bit field values.

Note

BT_ATT_CHAN_OPT_UNENHANCED_ONLY and BT_ATT_CHAN_OPT_ENHANCED_ONLY are mutually exclusive and both bits may not be set.

Values:

enumerator BT_ATT_CHAN_OPT_NONE = 0x0¶: Both Enhanced and Unenhanced channels can be used

enumerator BT_ATT_CHAN_OPT_UNENHANCED_ONLY = BIT(0)¶: Only Unenhanced channels will be used

enumerator BT_ATT_CHAN_OPT_ENHANCED_ONLY = BIT(1)¶: Only Enhanced channels will be used

Functions

int bt_eatt_connect(struct bt_conn *conn, size_t num_channels)¶

Connect Enhanced ATT channels.

Sends a series of Credit Based Connection Requests to connect num_channels Enhanced ATT channels. The peer may have limited resources and fewer channels may be created.

Parameters:

conn – The connection to send the request on
num_channels – The number of Enhanced ATT beares to request. Must be in the range 1 - CONFIG_BT_EATT_MAX , inclusive.

Return values:

-EINVAL – if num_channels is not in the allowed range or conn is NULL.
-ENOMEM – if less than num_channels are allocated.
0 – in case of success

Returns:

0 in case of success or negative value in case of error.

size_t bt_eatt_count(struct bt_conn *conn)¶

Get number of EATT channels connected.

Parameters:

conn – The connection to get the number of EATT channels for.

Returns:

The number of EATT channels connected. Returns 0 if conn is NULL or not connected.