:orphan:

.. title:: CONFIG_BT_BUF_ACL_TX_SIZE

.. kconfig:: CONFIG_BT_BUF_ACL_TX_SIZE

CONFIG_BT_BUF_ACL_TX_SIZE
#########################

*Maximum supported ACL size for outgoing data*

Type: ``int``

Help
====

.. code-block:: none

    Maximum supported ACL size of data packets sent from the Host to the
    Controller. This value does not include the HCI ACL header.
    The Host will segment the data transmitted to the Controller so that
    packets sent to the Controller will contain data up to this size.
    In a combined build this value will be set in both the Host and the
    Controller.
    In a Host-only build the Host will read the maximum ACL size supported
    by the Controller and use the smallest value supported by both the
    Bost and the Controller.
    The Host supports sending of larger L2CAP PDUs than the ACL size and
    will fragment L2CAP PDUs into ACL data packets.
    The Controller will return this value in the HCI LE Read Buffer
    Size command response. If this size if greater than effective Link
    Layer transmission size then the Controller will perform
    fragmentation before transmitting the packet(s) on air.
    If this value is less than the effective Link Layer transmission size
    then this will restrict the maximum Link Layer transmission size.
    Maximum is set to 251 due to implementation limitations (use of
    uint8_t for length field in PDU buffer structure).

Direct dependencies
===================

\ :kconfig:`BT_HCI <CONFIG_BT_HCI>` && \ :kconfig:`BT <CONFIG_BT>`

*(Includes any dependencies from ifs and menus.)*

Default
=======

- 27

Kconfig definition
==================



At ``<Zephyr Subsystem>/bluetooth/common/Kconfig:7``

Included via ``Kconfig:8`` → ``Kconfig.zephyr:44`` → ``<Zephyr Subsystem>/Kconfig:9`` → ``<Zephyr Subsystem>/bluetooth/Kconfig:173``

Menu path: (Top) → Sub Systems and OS Services → Bluetooth

.. code-block:: kconfig

    config BT_BUF_ACL_TX_SIZE
    	int "Maximum supported ACL size for outgoing data"
    	range 27 251
    	default 27
    	depends on BT_HCI && BT
    	help
    	  Maximum supported ACL size of data packets sent from the Host to the
    	  Controller. This value does not include the HCI ACL header.
    	  The Host will segment the data transmitted to the Controller so that
    	  packets sent to the Controller will contain data up to this size.
    	  In a combined build this value will be set in both the Host and the
    	  Controller.
    	  In a Host-only build the Host will read the maximum ACL size supported
    	  by the Controller and use the smallest value supported by both the
    	  Bost and the Controller.
    	  The Host supports sending of larger L2CAP PDUs than the ACL size and
    	  will fragment L2CAP PDUs into ACL data packets.
    	  The Controller will return this value in the HCI LE Read Buffer
    	  Size command response. If this size if greater than effective Link
    	  Layer transmission size then the Controller will perform
    	  fragmentation before transmitting the packet(s) on air.
    	  If this value is less than the effective Link Layer transmission size
    	  then this will restrict the maximum Link Layer transmission size.
    	  Maximum is set to 251 due to implementation limitations (use of
    	  uint8_t for length field in PDU buffer structure).

*(The 'depends on' condition includes propagated dependencies from ifs and menus.)*