HID Host API

hid_host.h

/**
 * @brief Set up HID Host 
 * @param hid_descriptor_storage
 * @param hid_descriptor_storage_len
 */
void hid_host_init(uint8_t * hid_descriptor_storage, uint16_t hid_descriptor_storage_len);

/**
 * @brief Register callback for the HID Host. 
 * @param callback
 */
void hid_host_register_packet_handler(btstack_packet_handler_t callback);

/*
 * @brief Create HID connection to HID Device and emit HID_SUBEVENT_CONNECTION_OPENED event with status code, 
 * followed by HID_SUBEVENT_DESCRIPTOR_AVAILABLE that informs if the HID Descriptor was found. In the case of incoming
 * connection, i.e. HID Device initiating the connection, the HID_SUBEVENT_DESCRIPTOR_AVAILABLE is delayed, and the reports 
 * may already come via HID_SUBEVENT_REPORT event. It is up to the application code if 
 * these reports should be buffered or ignored until the descriptor is available.
 * @note  HID_PROTOCOL_MODE_REPORT_WITH_FALLBACK_TO_BOOT will try ti set up REPORT mode, but fallback to BOOT mode if necessary. 
 * @note  HID_SUBEVENT_DESCRIPTOR_AVAILABLE possible status values are:
 * - ERROR_CODE_SUCCESS if descriptor available, 
 * - ERROR_CODE_UNSUPPORTED_FEATURE_OR_PARAMETER_VALUE if not, and 
 * - ERROR_CODE_MEMORY_CAPACITY_EXCEEDED if descriptor is larger then the available space
 * @param remote_addr
 * @param protocol_mode see hid_protocol_mode_t in btstack_hid.h
 * @param hid_cid to use for other commands
 * @result status ERROR_CODE_SUCCESS on success, otherwise ERROR_CODE_COMMAND_DISALLOWED, BTSTACK_MEMORY_ALLOC_FAILED
 */
uint8_t hid_host_connect(bd_addr_t remote_addr, hid_protocol_mode_t protocol_mode, uint16_t * hid_cid);


/*
 * @brief Accept incoming HID connection, this should be called upon receiving HID_SUBEVENT_INCOMING_CONNECTION event.
 * @param hid_cid
 * @param protocol_mode see hid_protocol_mode_t in btstack_hid.h
 * @result status ERROR_CODE_SUCCESS on success, otherwise ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER, ERROR_CODE_COMMAND_DISALLOWED
 */
uint8_t hid_host_accept_connection(uint16_t hid_cid, hid_protocol_mode_t protocol_mode);

/*
 * @brief Decline incoming HID connection, this should be called upon receiving HID_SUBEVENT_INCOMING_CONNECTION event.
 * @param hid_cid
 * @result status ERROR_CODE_SUCCESS on success, otherwise ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER, ERROR_CODE_COMMAND_DISALLOWED
 */
uint8_t hid_host_decline_connection(uint16_t hid_cid);

/*
 * @brief Disconnect from HID Device and emit HID_SUBEVENT_CONNECTION_CLOSED event.
 * @param hid_cid
 */
void hid_host_disconnect(uint16_t hid_cid);

// Control messages:

/*
 * @brief Send SUSPEND control signal to connected HID Device. A Bluetooth HID Device which receives a SUSPEND control signal
 * may optionally disconnect from the Bluetooth HID Host.
 * @param hid_cid
 * @result status ERROR_CODE_SUCCESS on success, otherwise ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER, ERROR_CODE_COMMAND_DISALLOWED
 */
uint8_t hid_host_send_suspend(uint16_t hid_cid);

/*
 * @brief Order connected HID Device to exit suspend mode. 
 * The Bluetooth HID Device shall send a report to the Bluetooth HID Host.
 * @param hid_cid
 * @result status ERROR_CODE_SUCCESS on success, otherwise ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER, ERROR_CODE_COMMAND_DISALLOWED
 */
uint8_t hid_host_send_exit_suspend(uint16_t hid_cid);

/*
 * @brief Unplug connected HID Device. 
 * @note This is the only command that can be also received from HID Device. It will be indicated by receiving 
 * HID_SUBEVENT_VIRTUAL_CABLE_UNPLUG event, as well as disconnecting HID Host from device.
 * @param hid_cid
 * @result status ERROR_CODE_SUCCESS on success, otherwise ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER, ERROR_CODE_COMMAND_DISALLOWED
 */
uint8_t hid_host_send_virtual_cable_unplug(uint16_t hid_cid);

/*
 * @brief Set Protocol Mode on the Bluetooth HID Device and emit HID_SUBEVENT_SET_PROTOCOL_RESPONSE event with handshake_status, see hid_handshake_param_type_t
 * @param hid_cid
 * @param protocol_mode see hid_protocol_mode_t in btstack_hid.h
 * @result status ERROR_CODE_SUCCESS on success, otherwise ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER, ERROR_CODE_COMMAND_DISALLOWED
 */
uint8_t hid_host_send_set_protocol_mode(uint16_t hid_cid, hid_protocol_mode_t protocol_mode);

/*
 * @brief Retrieve the Protocol Mode of the Bluetooth HID Device and emit HID_SUBEVENT_GET_PROTOCOL_RESPONSE with handshake_status, see hid_handshake_param_type_t
 * @param hid_cid
 * @param protocol_mode see hid_protocol_mode_t in btstack_hid.h
 * @result status ERROR_CODE_SUCCESS on success, otherwise ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER, ERROR_CODE_COMMAND_DISALLOWED
 */
uint8_t hid_host_send_get_protocol(uint16_t hid_cid);

/*

 * @brief Send report to a Bluetooth HID Device and emit HID_SUBEVENT_SET_REPORT_RESPONSE with handshake_status, see hid_handshake_param_type_t. The Bluetooth HID Host shall send complete reports.
 * @param hid_cid
 * @param report_type see hid_report_type_t in btstack_hid.h
 * @param report_id
 * @param report
 * @param report_len
 * @result status ERROR_CODE_SUCCESS on success, otherwise ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER, ERROR_CODE_COMMAND_DISALLOWED
 */
uint8_t hid_host_send_set_report(uint16_t hid_cid, hid_report_type_t report_type, uint8_t report_id, const uint8_t * report, uint8_t report_len);

/*
 * @brief Request a HID report from the Bluetooth HID Device and emit HID_SUBEVENT_GET_REPORT_RESPONSE event with with handshake_status, see hid_handshake_param_type_t. 
 * Polling Bluetooth HID Devices using the GET_REPORT transfer is costly in terms of time and overhead, 
 * and should be avoided whenever possible. The GET_REPORT transfer is typically only used by applications 
 * to determine the initial state of a Bluetooth HID Device. If the state of a report changes frequently, 
 * then the report should be reported over the more efficient Interrupt channel, see hid_host_send_report.
 * @param hid_cid
 * @param report_type see hid_report_type_t in btstack_hid.h
 * @param report_id
 * @result status ERROR_CODE_SUCCESS on success, otherwise ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER, ERROR_CODE_COMMAND_DISALLOWED
 */
uint8_t hid_host_send_get_report(uint16_t hid_cid, hid_report_type_t report_type, uint8_t report_id);

/**
 * @brief Send HID output report on interrupt channel.
 * @param hid_cid
 * @param report_id
 * @param report
 * @param report_len
 * @result status ERROR_CODE_SUCCESS on success, otherwise ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER, ERROR_CODE_COMMAND_DISALLOWED
 */
uint8_t hid_host_send_report(uint16_t hid_cid, uint8_t report_id, const uint8_t * report, uint8_t report_len);

/*
 * @brief Get descriptor data
 * @param hid_cid
 * @result data
 */
const uint8_t * hid_descriptor_storage_get_descriptor_data(uint16_t hid_cid);

/*
 * @brief Get descriptor length
 * @param hid_cid
 * @result length
 */
uint16_t hid_descriptor_storage_get_descriptor_len(uint16_t hid_cid);