btstack/CHANGELOG.md

Change Log

All notable changes to this project will be documented in this file.

The format is based on Keep a Changelog and this project adheres to Semantic Versioning.

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[Unreleased]

Fixed

Added

Changed

Changes October 2020

Fixed

• AVRCP/AVCTP: report AVRCP 1.6 and AVCTP 1.4 in SDP record

Added

Changed

Changes September 2020

Fixed

• HFP: fix parsing of ranges e.g. in +CIND responses
• AVDTP, AVRCP: fix bugs due to transaction id overrun
• A2DP Source: fix issues with stream configuration by sink
• hci_dump: fix tv_us calculation for non-posix / embedded systems with binary output

Added

• btstack_ring_buffer: add btstack_ring_buffer_reset to reset it to initial state/empty
• GAP: Support for address resolution of resolvable private addresses by Controller with ENABLE_LE_PRIVACY_ADDRESS_RESOLUTION

Changed

• AVDTP, AVRCP, HSP: schedule SDP query, avoids avoids 'command disallowed' if SDP client is busy
• HSP, HFP: allow to configure usable SCO packet types
• cc256x: update CC256xC init script to v1.4
• A2DP Source: use Get All Capabilities if supported by remote get Delay Reporting capability

Changes August 2020

Fixed

• ESP32: fix authentication for incoming Secure Connections
• AVDTP: Fix forwarding of Delay reports
• STM32-F4Discovery: fix pan_lwip_http_server by increasing HCI_ACL_PAYLOAD_SIZE
• tool/create_packet_log: basic support for 16-bit Unicode log files from Windows

Added

• btstack_run_loop_base: added btstack_run_loop_base_dump_timer
• GAP: request role change for classic connection via gap_request_role
• GAP: LE Whitelist API with gap_le_whitelist_x with x = add, remove, clear and new gap_connect_with_whitelist
• SDP Client: add sdp_client_register_query_callback() allows to register query request instead of polling sdp_client_ready()
• BNEP lwIP: add bnep_lwip_connect to establish BNEP connection and manage lwIP network interface
• New btstack_linked_queue utility, a linked list-based queue with first-in-first-out semantics and constant time enqueue/dequeue operations
• btstack_tlv_posix: add btstack_tlv_posix_deinit
• New btpclient for use with auto-pts project

Changed

• GAP: treat AES-CCM encrypted connection as mutually authenticated (BIAS)
• GAP: 'gap_auto_connect_x' API deprecated. Please direclty manage LE Whitelist with gap_le_whitelist_* functions and call gap_connect_with_whitelist instead
• example/hid_host_demo: try to become master for incoming connections
• btstack_run_loop: use btstack_assert instead of local while(true)
• att_db_util: allow to reset att_db via att_db_util_init

Changes July 2020

Fixed

• AVDTP: fix invalid response for Get Capabilities request if Delay Reporting was supported
• AVDTP: handle concurrent signaling establishment with reject and retry

Added

• example/hid_host_demo: support reconnect from HID device
• Crypto: support software AES128 for AES-CCM operations
• AVRCP: introduced AVRCP_FEATURE_MASK_* as alternative to avrcp_controller_supported_feature_t and avrcp_target_supported_feature_t enums
• btstack_audio: add set_volume() to sink and set_gain() to source interfaces, minimal volume control for portaudio playback
• AVDTP: renamed definition of supported features from AVDTP_SOURCE_SF_ and AVDTP_SINK_SF_ to AVDTP_SOURCE_FEATURE_MASK_ and AVDTP_SINK_FEATURE_MASK_ respectively
• GAP: Provide gap_get_role to query master/slave role for HCI connection handle
• GAP: Provide gap_pin_code_response_binary to use binary data as PIN, e.g. for pairing with Nintendo Wii Remote

Changed

• GAP: set minimum required encryption key size for Classic connections back from 16 to 7, matching the Core spec

Changes June 2020

Fixed

• HFP: Fix parsing of empty fields, e.g. phone number in +CLCC and other AT commands
• sm: Fix validation of confirm value for secure connection Passkey entry
• AVRCP: handle concurrent signaling establishment with reject and retry

Added

• GAP: Detect Secure Connection -> Legacy Connection Downgrade Attack by remote features and actual encryption type (BIAS)
• GAP: Mutual authentication: request authentication after Classic connection got encrypted (BIAS)
• Windows port for Dialog DA14585 connected via serial port

Changes

• CVSD PLC: treat zero frames as good and allow to mark data as bad, e.g. if reported by Controller as erroneous

Changes May 2020

Fixed

• hfp_hf, hsp_hs: use eSCO params in accept sco connection only for incoming eSCO connections
• pbap_client: fix PBAP UUID len on connect message
• sm: fix secure connection pairing as peripheral when local user confirmation happens after remote one
• A2DP Source: only connect to remote sink stream endpoints
• btstack_hal_flash_memory: fix write of 0xff bytes to simulated flash
• hsp_hs: fix disconnect if audio not connected
• hsp_ag: fix accept incoming connection

Added

• example/le_mitm: MITM implementation that forwards ATT PDUs and allows for pairing
• GAP: gap_set_security_level sets required security level for incoming and outgoing connections
• cc256x: allow to specify power vector for each modulation type
• FreeRTOS: btstack_run_loop_freertos_trigger_exit allows to request run loop exit
• sm: support LE Secure Connections Only mode with sm_set_secure_connections_only_mode
• GAP: enable BR/EDR Secure Connections if supported, add gap_secure_connections_enable

Changed

• L2CAP ERTM: send extended features request only once per HCI connection

Changes April 2020

Fixed

• hog_mouse_demo/hog_keyboard_demo: handle set protocol mode = boot protocol mode
• HCI: only update BD_ADDR placeholder in shortened and complete name in EIR data, limit device name to 240/248 bytes

Added

• GAP: gap_set_allow_role_switch allows to prevent role switch in outgoing classic ACL connections
• example: hog_boot_host_demo implements an HID-over-GATT Boot Host that supports keyboard and mouse
• HCI: add ENABLE_LE_LIMIT_ACL_FRAGMENT_BY_MAX_OCTETS that forces fragmentation of ACL-LE packets to fit into over-the-air packet

Changed

• Broadcom/Cypress: wait 300 ms after PatchRAM update in hci.c to assert Controller is ready
• esp32: provide esp-idf/component/btstack/btstack_port_esp32.c and only minimal app_main in template/main/main.c
• att_db: skip att_read_callback for ATT Read Blob Request if offset == value_len

Changes March 2020

Fixed

• GAP: fixed gap_set_scan_parameters() if issued right before gap_start_scan()
• HCI: only send HCI Read Local Encryption Key Size if supported by Controller

Added

• GATT Client: allow to register for any notification/indication and/or any connection
• HCI: added hci_read_inquiry_scan_activity and hci_write_inquiry_scan_activity commands
• chipset: assert hci packet buffers are suitable for firmware upload or patches (atwilc3000,bcm,cc256x,intel)
• btstack_util: added btstack_replace_bd_addr_placeholder

Changed

• AVRCP Target: volume in avrcp_target_volume_changed is reported as current value in interim response to register for volume change notifications
• SDP Client: query attributes 0x0000..0xffff instead of 0x0001..0xffff to match other stacks / improve compatibility with bad sdp server implementations

Changes Februar 2020

Fixed

• AVRCP Target: fix reporting of PLAYBACK_STATUS_CHANGED
• HCI: handle reconnect request for Classic and LE connections triggered by packet handler for Disconnection Complete Event

Changed

• hid_host_mode: allow sniff mode

Added

• port/qt-usb and port/qt-h4: integrate BTstack Qt run loop for Unix- and Win32-based Qt application connected to Bluetooth module via H4 over serial port or USB

Changes January 2020

Fixed

• L2CAP ERTM: avoid read-after-free on decline of incoming connection
• GATT Client: set uuid16 to zero when deserializing uuid128 services, characteristics, and descriptors
• att_db_util: fix realloc of att db buffer for large attributes
• btstack_tlv_posix: only keep last value in memory, fix delete operation
• l2cap_signaling: use packet boundary flags 0x00 for LE signaling packets (ignoring hci_non_flushable_packet_boundary_flag_supported())

Added

• att_db_util: provide GATT Database Hash via att_db_util_hash_calc
• GATT Compiler: provide GATT Database Hash via GATT_DATABASE_HASH Characteristic
• ATT Server: validate request pdu length

Changed

• Crypto: update AES-CMAC implementation to access all message bytes sequentially

Changes December 2019

Fixed

• example/pan_lwip_http_server: use Network Access Point, CoD
• sm: emit pairing complete in master role when no keys are distributed / bonding disabled

Added

Changed

• Updated CC256x initscript: CC256xC v1.3
• ESP32: add CMake project files

Changes November 2019

Fixed

• AVDTP Source: return correct avdtp_cid and local_seid in AVDTP_SUBEVENT_STREAMING_CAN_SEND_MEDIA_PACKET_NOW
• L2CAP: send LE Data Channel SDUs round robin with other data
• L2CAP ERTM: send ERTM I-frames round robin with other data

Added

• ATT Server: return error if request to send now for Notification or Indication already registered
• Linked List: return if item was added for btstack_linked_list_add[_tail]
• btstack_run_loop_remove: return bool true if timer/data source was removed
• segger-rtt: allow to configure with SEGGER_RTT_PACKETLOG_* directives, update to v6.54
• GAP: support setting Link Supervision Timetout for outgoing Classic connections using gap_set_link_supervision_timeout
• lwip: add download test files to http server demo

Changed

• Linked List: return bool true if item was removed

Changes October 2019

Fixed

Added

• btstack_bool.h: provide boolean type 'bool' via <stdbool.h> or as backport
• provide btstack_assert(condition)
• H4 Transport: avoid calling hci_transport_h4_trigger_next_read when transport is closed

Changed

• libusb and posix ports: store bonding information in TLV

Changes September 2019

Fixed

• L2CAP ERTM: assert that packet can be stored in fragment buffers in ertm
• L2CAP ERTM: reject incoming connection if ERTM is configured as mandatory but not supported by remote
• GATT Client: allow Write Without Response independent of other requests

Added

• GAP: allow to reject GAP classic connection via gap_register_classic_connection_filter
• GAP: support reading RSSI for Classic+LE using gap_read_rssi. Emits GAP_EVENT_RSSI_MEASUREMENT

Changed

• Bluetooth and BTstack Error Codes and Events: collect status codes in bluetooth.h and events in btstack_defines.h
• bluetooth.h: extract internal defintitions to respective protocol layers
• Updated CC256x initscripts (CC256xB v1.8, CC256xC v1.2, CC256xC v1.2)

Changes August 2019

Fixed

• POSIX, WICED, Windows, FreeRTOS run loops: handle time_ms overrun after 49 days
• RFCOMM: accept incoming L2CAP connection in Basic mode if ERTM is enabled but not requested for this connection
• RFCOMM: limit RFCOMM MTU by local L2CAP MTU for outgoing connections (only revelvant for ERTM)
• L2CAP ERTM: stop timers on disconnect
• L2CAP ERTM: fix sending of segmented SDUs
• L2CAP ERTM: handle unsupported Information Response
• SM: generate local nonce for confirm value in JW+NC+PK in Secure Connections Responder role

Added

• btstack_run_loop_base: portable implementation of timer and data source management as base for platform specific implementations

Changed

• FreeRTOS: use xQueueCreateStatic (static variant of xQueueCreate) if available for static memory-only setups
• L2CAP ERTM: handle invalid Information Response (assume no extended features supported)
• POSIX: use monotonic clock as timebase if available
• HCI Transport H4/H5/EM9304 SPI: ignore block read/sent from UART driver when closed
• HCI: Read Encryption Key Size after encryption was enabled
• Errata 11838:
  • GAP: gap_set_required_encryption_key_size allows to set the required key size, default = 16 (max)
  • GAP: validate encryption key size to emit GAP Security Levels

Changes July 2019

Fixed

• SM: Fixed regression introduced in f3582630
• L2CAP: avoid reading l2cap signaling command len out of bounds
• HCI Transport H4/H5/EM9304 SPI: fix payload size checks (also for 8/16-bit platforms)

Changed

• SM: Start encryption upon receiving slave securiy request if bonded
• hci: use 2 as HCI_INCOMING_PRE_BUFFER_SIZE in LE-only configuration for GATT Client

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Changes June 2019

Changed

• FreeRTOS: use freertos/.. prefix to include FreeRTOS headers if HAVE_FREERTOS_INCLUDE_PREFIX is defined
• BNEP: add Connection Handle to BNEP_EVENT_CHANNEL_OPENED
• Examples: renamed le_counter to gatt_counter and le_streamer to le_streamer_server to indicate suppport for GATT over BR/EDR

Fixed

• BNEP: Bluetooth address is stored in little-endian format for all BNEP_EVENT_*
• libusb: avoid use-after-free for SCO packets on disconnect

Added

• example: pan_lwip_http_server using lwIP as network stack to implement PAN NAP service
• platform/lwip/bnep_lwip.c: BNEP lwIP adapter that forwards packets between BNEP service and lwIP
• ENABLE_GATT_OVER_CLASSIC enables support for GATT over BR/EDR in att_server

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Changes May 2019

Changed

• ESP32: Configure SCO over HCI after power up
• btstack_tlv_flash_bank: support targets where a value cannot be overwritten with zero. When ENABLE_TLV_FLASH_EXPLICIT_DELETE_FIELD is defined, an explicit delete field is used to indicate an invalid entry.

Fixed

• SM: Avoid potential use-after-free on immediate disconnect (lookup connection via con handle instead of storing pointer)

Added

• gatt_client: emit query complete event for signed write operation
• hci_transport_h4: add workaround for flow control bug in CYW2070x, enable with ENABLE_CYPRESS_BAUDRATE_CHANGE_FLOWCONTROL_BUG_WORKAROUND

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Changes April 2019

Changed

• ESP32: use micro-ecc from 3rd-party as esp-idf removed it in their 3.3 release

Fixed

• hci: pad LE Scan response with zeroes
• SM: store local CSRK
• ATT DB: call write callback for validated signed writes
• ATT Server: abort signed write validation on incoming new request
• Bluetooth SIG web scraping tools updated
• libusb: compiles for FreeBSD

Added

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Changes March 2019

Changed

• use Makefile for stm32-f4discovery-cc256x port
• le_device_db: add secure_connection argument to le_device_db_encryption_set and le_device_db_encryption_get

Fixed

• SM: Use provided authentication requirements in slave security request

Added

• port/stm32-f4discovery-cc256x: add support for built-in MEMS microphone
• SM: Track if connection encryption is based on LE Secure Connection pairing
• ATT DB: Validate if connection encrypted is based on SC if requested
• att_db_util: support ATT_SECURITY_AUTHENTICATED_SC permission flag
• GATT Compiler: support READ_AUTHENTICATED and WRITE_AUTHENTICATED permsission flags
• ESP32: erase nvs flash is newer nvs version found
• libusb: add support for nRF52840-PCA10056 running Zephyr hci_usb example
• port/stm32-l073rz-nucleo-em9304 for Nucleo L073RZ with EM9304 DVK, replaces port/stm32-l053r8-nucleo-em9304

Changes February 2019

Changed

• example/a2dp_sink_demo: use linear resampling to fix sample rate drift
• btstack_audio: split interface into sink and source

Fixed

• Crypto: fix lockup when stack is shutdown while waiting for result of HCI Command, e.g. LE Read Local P256 Public Key
• SM: Avoid SM_EVENT_PAIRING_COMPLETE with ERROR_CODE_REMOTE_USER_TERMINATED_CONNECTION after successful pairing in responder role

Added

• example/a2dp_sink_demo: add target role, support volume control on both devices
• example/audio_duplex: playback audio audio source on audio sink (test audio path)
• btstack_audio_embedded: implement audio source path

---

Changes January 2019

Changed

• L2CAP: provide channel mode (basic/ertm) and fcs option in L2CAP_EVENT_CHANNEL_OPENED
• RFCOMM: support L2CAP ERTM. Callbacks passed to rfcomm_enable_l2cap_ertm() are used to manage ERTM buffers

Added

• L2CAP: emit L2CAP_EVENT_ERTM_BUFFER_RELEASED if ERTM buffer not needed/used anymore
• L2CAP: add fcs_option to ERTM config l2cap_ertm_config_t
• HCI: validate advertisement data length field when generating GAP_EVENT_ADVERTISING_REPORT
• ad_parser: validate data element length fields in ad_iterator_has_more
• Raspberry Pi 3 A+/B+ port in port/raspi, starts without power cycle

Fixed

• HCI: release outgoing buffer on disconnect if waiting to send another ACL fragment
• POSIX: use correct baudrate enums for baud rates higher than 921600 (Linux)
• Crypto: directly process queued crypto operation on HCI result

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Changes December 2018

Added

• SM: generate and store ER / IR keys in TLV, unless manually set by application
• hci_dump: support PacketLogger or BlueZ format output via SEGGER RTT Channel 1 Up

Fixed

• SM: fix internal buffer overrun during random address generation

Changes November 2018

Added

• GAP: gap_le_connection_interval provides connection interval for conn handle
• Nordic SPP Service Server: GATT service that emulates a serial port over BLE based on Nordic Semiconductor documentation.
• uBlox SPP Service Server: GATT service that emulates a serial port over BLE based on uBlox documentation.
• SM: ENABLE_LE_CENTRAL_AUTO_ENCRYPTION triggers automatic encryption on connect to bonded devices
• SM: generate and store ER / IR keys in TLV, unless manually set by application

Fixed

• SM: prevent random address updates if gap_random_address_set was used
• SM: fix internal buffer overrun that can cause storing of bonding information to fail
• SM: ignore Slave Security Request after sending own Pairing Request
• L2CAP: fix use after free on disconnect if ERTM is enabled
• HFP: Handle multiple commands/responses in single RFCOMM packet
• Memory Pools: clear all buffers before use

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Changes October 2018

Added

• SDP Server: queue incoming connections when already connected instead of rejecting them
• GAP: Support enter/exit sniff mode via gap_sniff_mode_enter/exit. gap_set_default_link_policy_settings is needed to enable sniff mode in general.
• HIDS Device: GATT service that exposes HID reports intended for HID Devices, like keyboard and mouse.

Fixed

• HCI: fix bug in gap_inquiry_stop that triggered additional GAP_EVENT_INQUIRY_COMPLETE instead of stopping the inquiry
• L2CAP: fix issue with outgoing connection before read remote supported complete when other channels exist
• L2CAP ERTM: allow SDU of szie MPS in first packet that contains L2CAP SDU Length
• L2CAP ERTM: fix memory corruption triggered if local_mtu > mps
• L2CAP ERTM: fix outgoing fragment management
• HFP: decline incoming RFCOMM connection after outgoing connection was started
• AVRCP: fix crash on disconnect of connection established by remote

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Changes September 2018

Fixed

• HCI: Error creating outgoing connection (e.g. Connection Limit Exceeded) now handled
• L2CAP: Error creating outgoing connection (e.g. Connection Limit Exceeded) now handled
• L2CAP: Evaluate 'can send now' on HCI Disconnect as ACL buffers in Bluetooth Controller have been used for the closed connection are freed implicitly
• L2CAP: Check can send now before sending extended information requeste needed for ERTM mode
• L2CAP: Use valid signaling identifier for L2CAP Connection Parameter Update Request
• RFCOMM: Trigger l2cap request to send on rfcomm credits when client is waiting to sendtrigger l2cap request to send on rfcomm credits when client is waiting to send
• RFCOMM: Avoid use-after-free on channel finalize
• GATT Client: stop timer on disconnect - fixes use after free / crash

Added

• A2DP Source: Support stream reconfiguration (a2dp_source_reconfigure_stream_sampling_frequency)
• 3rd-party: yxml is used for PBAP vCard list parsing
• cc256xC: new v1.1 init scripts

---

Changes August 2018

Added

• PBAP: added pbap_get_phonebook_size() to get phonebook entry count

Fixed

• GATT Server: Allow enable Notifications/Indication with Write Command. Fixes issue with some Android devices.
• SM: fix pairing for Secure Connections with Bonding if remote sends additional keys
• SM: drop LTK flag from Pairing Response for Secure Connections
• L2CAP: fix emitted L2CAP_EVENT_CONNECTION_PARAMETER_UPDATE_REQUEST

Changes June 2018

Added

• btstack_audio.h: application level API for audio playback and recording
• embedded/hal_audio.h: low-level API for audio playback and recording
• HID Device: hid_device_connect(..) function
• ESP32: implement hal_audio
• DA14585: support for Dialog Semiconductor DA14585 LE-only controller
• Raspberry Pi 3 + Raspberry Pi Zero W port in port/raspi

Changed

• Errata 10734:
  • SM: Generate new EC Public Keypair after each pairing
  • SM: Abort failure with DHKEY_CHECK_FAILED if received public key is invalid (instead of unspecified error)
• btstack.h: only include classic headers if ENABLE_CLASSIC is defined
• windows: ignore virtual Bluetooth adapter provided by VMware
• Replaced HCI_PACKET_BUFFER_SIZE with HCI_INCOMING_PACKET_BUFFER_SIZE and HCI_OUTGOING_PACKET_BUFFER_SIZE

---

Changes June 2018

Fixed

• HFP: Fix Wide Band Speech bit in SDP record for both HF/AG. Missing bit prevents macOS from using mSBC
• ATT Server: send ATT_EVENT_HANDLE_VALUE_INDICATION_COMPLETE with status ATT_HANDLE_VALUE_INDICATION_DISCONNECT on disconnect
• AVRCP Controller: fix parsing of now playing info

Changed

• ATT Server: ATT_HANDLE_VALUE_INDICATION_DISCONNECT is delivered to service handler if registered

Added

• ATT Server: packet handler field added to att_service_handler_t to receive: connect/disconnect, atu exchange, indication complete

---

Changes May 2018

Added

• GAP: re-encrypt outgoing connection if bonded
• ATT Server: wait until re-encryption is complete
• GATT Client: wait until re-encryption is complete
• ATT Server: added att_server_request_to_send_notification and att_server_request_to_send_indication
• GATT Client: if ENABLE_GATT_CLIENT_PAIRING, GATT Client starts pairing and retry operation on security error

Changed

• ATT Server: att_server_register_can_send_now_callback is deprecated, use att_server_request_to_send_notification/indication instead

Fixed

• SM: Fix LE Secure Connection pairing in Central role
• le_device_db_tlv: fix seq nr management
• SM: improve le_device_db lookup and storing of IRK
• GATT Server: fix lookup for Client Characteristic Configuration in services with multiple Characteristics
• RFCOMM: emit channel closed on HCI/L2CAP disconnect after sending DISC while expecting UA

---

Changes April 2018

Added

• Crypto: btstack_crypo.h provides cryptographic functions for random data generation, AES128, EEC, CBC-MAC (Mesh)
• SM: support pairing using Out-of-Band (OOB) data with LE Secure Connections
• Embedded: support btstack_stdin via SEGGER RTT

Changed

• att_db_util: added security requirement arguments to characteristic creators
• SM: use btstack_crypto for cryptographpic functions
• GAP: security level for Classic protocols (asides SDP) raised to 2 (encryption)

Fixed

• HFP: fix answer call command
• HCI: fix buffer overrun in gap_inquiry_explode
• SDP: free service record item on sdp_unregister_service

Changes March 2018

Added

• GAP: allow to limit number of connections in LE Peripheral role with gap_set_max_number_peripheral_connections
• ATT Server: support for delayed ATT read response, see example/att_delayed_read_response.c
• ATT Server: allow to specify security requirements seperately for read/writes. .h files need to be regenerated

Fixed

• RFCOMM: fix infinite loop on L2CAP connection error (regression from 4c3eeed1)
• HSP HS: accept incomming SCO connection
• SM: fix iteration over LE Device DB entries for bonding and address resolving
• SM: store pairing information only if both devices have requested bonding

---

Changes February 2018

Added

• GATT Client: gatt_client_request_can_write_without_response_event() causes GATT_EVENT_CAN_WRITE_WITHOUT_RESPONSE
• SM: new event SM_EVENT_PAIRING_COMPLETE
• GAP: support iteration over stored Classic link keys: gap_link_key_iterator_init, gap_link_key_iterator_get_next, gap_link_key_iterator_done
• GAP: add gap_delete_all_link_keys

Changed

• GATT Client: round robin for multiple connections
• ATT Dispatch: round robin for ATT Server & GATT Client
• L2CAP: round robin for all L2CAP channels (fixed and dynamic)
• btstack_link_key_db: addition functions for link key iteration
• GAP: LE scanning enabled not reset on HCI Reset -> can be enabled before HCI Power Up
• CSR: set all keys in psram instead of default

Fixed

• tc3556x: fix startup after baud rate change

---

Changes January 2018

Added

• Port for Windows with Zephyr HCI Firmware connected via serial port
• em9304: upload patch containers during HCI bootup
• Makefile for STM32-F4Discovery port
• support for console out via SEGGER RTT
• LE Data Channels example in BTstack and iOS example on GitHub
• LE Streamer Client can send as fast as possbile as well
• L2CAP: option to limit ATT MTU via l2cap_set_max_le_mtu

Changed

• HCI: allow to set hci_set_master_slave_policy (0: try to become master, 1: accept slave)
• GAP: gap_set_connection_parameters includes scan interval and window params
• GATT Client: GATT_EVENT_MTU indicates max MTU
• ATT DB Util: attribute handle is returned for new Services and Characteristics

Fixed

• Windows: retry serial port operations if not all bytes have been read/written
• HFP: avoid buffer overflows setting up messages
• SBC Decoder: improved error handling for invalid SBC audio data
• GAP: fix Connection Parameter Response in Central role
• ATT DB Util: update pointer to database in case of realloc
• GATT Client: set UUID16 field if 16-bit UUID is stored as UUID128
• GAP: release HCI Connnection after gap_le_conne
• ATT: Exchanged MTU is propagate to ATT Server and GATT Client

---

Changes December 2017

Added

• Introduced btstack_network.h network interface abstraction
• btstack_network_posix implementation using Linux tun/tap interface
• WICED: support for btstack_stdin (HAVE_STDIN)
• GATT Server: Writes to GATT Client Characteristic Configuration are stored in TLV and restored on reconnect. The db.h file generated from db.gatt needs to be re-created.
• TLV: global TLV instance available via btstack_tlv_get_instance() (src/btstack_tlv.h)
• TLV: POSIX implementation that appends to a file on disk (platform/posix/btstack_tlv_posix.c
• LE Device DB TLV: overwrite oldest entry if no free entries available
• SM: allow to set fixed passkey in display role using sm_use_fixed_passkey_in_display_role
• Example/hid_host_demo with HID parser and support for basic US keyboard layout
• EM9304: custom HCI Transport implementation for EM9304 on top of btstack_em9304_spi.h platform abstraction only requires hal_em9304_spi.h to be implemented for new ports
• Port for Apollo2 MCU with EM9304 (ports/apollo2-em9304)

Changed

• panu_demo: uses btstack_network.h now
• WICED: configure printf to replace Linefeed with CRLF
• SBC: split btstack_sbc_bludroid.c into seperate encoder and decoder implementations

Fixed

• RFCOMM: support connection requests during connection failure
• L2CAP: support connection requests during connection failure
• L2CAP: fix default remote MTU as 672 instead of 48 (Minimal MTU)
• HCI: avoid double free during halting
• SM: fixed reconnect using legacy pairing in slave role