MAVLink Communication

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Revision as of 11:11, 2 September 2019 by OlliW (talk | contribs) (→‎Passthrough)
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The information on this page refers to firmware v2.43 and higher.

In addition to the serial commands, the STorM32 controller also understands MAVLink messages, as defined in the MAVLink standard. The STorM32 controller in fact supports a rich set of MAVLink messages and features, as well as the MAVLink 2 protocol, and might be by far the most integrated MAVLink capable gimbal controller available.

The STorM32 controller integrates two MAVLink components, which in the following are referred to as the MAVLink Gimbal and MAVLink Camera components:

  • MAVLink Gimbal: This component deals with the gimbal operation, and is the part as you know it from older firmware versions.
  • MAVLink Camera: This component is related to the NT Camera, and provides a Camera Protocol microservice server. It allows you to control the camera through MAVLink in unprecedented useful ways.

The MAVLink Gimbal and MAVLink Camera components share some parameters, but function-wise are independent of each other. That is, both can be used, the MAVLink Gimbal component can be used without the MAVLink Camera component, and vice versa.

Comment: In the [GUI:Dashboard], the MAVLINK field shows MAVLINK is PRESENT when the STorM32 controller is receiving valid MAVLink messages, i.e., when a MAVLink connection is established. This can be handy for diagnosis.

Comment: In case you find it somewhat confusing what "two MAVLink components" is supposed to mean, then just connect the STorM32 (with both components enabled) to MissionPlanner: I will find that it will show you two components, one named Gimbal and the other one named Camera :).

Parameters

The MAVLink parameters are located in the [GUI:Interfaces Tool] window, which is accessible via the [GUI:Experts Only] menu.

It has the following parameters:

  • Mavlink Configuration: Enables the MAVLink Gimbal component, and activates emission of its heartbeat and other messages.
  • Mavlink Com Port: Selects the com port which shall be used for the MAVLink communication. Applies to both the MAVLink Gimbal and MAVLink Camera components.
  • Mavlink System ID: Sets the system ID of the STorM32 controller (default = “1”). Applies to both the MAVLink Gimbal and MAVLink Camera components. If it is set to “0”, then the system ID is autodetected, i.e., the STorM32 waits for incoming heartbeat messages from an autopilot and when uses its system ID.
  • Mavlink Component ID: Sets the component ID of the MAVLink Gimbal component (default = “154” = MAV_COMP_ID_GIMBAL).
  • Mavlink Version: Sets the used MAVLink protocol version. Applies to both the MAVLink Gimbal and MAVLink Camera components. Must be set to “Mavlink2” for the MAVLink Camera component to fully work.
  • Mavlink Camera: Enables the MAVLink Camera component and sets its component ID.

The STorM32 system ID should match the system ID of the autopilot (this can be e.g. achieved by using autodetection, Mavlink System ID = “0”). The component ID should usually not be changed.

STorM32 supports the MAVLink 1 and MAVLink 2 protocols, which can be set via the parameter Mavlink Version. Per default MAVLink 2 is disabled, but it is highly recommended to enable it by setting Mavlink Version = “Mavlink2”.

Comment: The STorM32 controller always accepts and serves incoming MAVLink messages on any of its serial ports, irrespective of the setting in the Mavlink Configuration and Mavlink ComPort parameters. However, all outgoing messages such as the heartbeats are emitted only on the selected serial port, and this port also does not accept incoming serial commands, i.e., is exclusive for MAVLink communication.

Comment: The baudrate of the selected serial port is determined by the respective baudrate parameter in the [GUI:Expert] tab.

Comment: For v1.x boards: When the UART port is selected, one cannot use a BT module and a serial MAVLink connection at the same time.

MAVLink Gimbal

In order to enable the MAVLink Gimbal component, the emission of its heartbeat must be enabled by setting the Mavlink Configuration parameter to “emit heartbeat” or higher.

The system ID and component ID can be adjusted via the Mavlink System ID and Mavlink Component ID parameters. They usually can be left at their default values.

Passthrough

It is possible to connect the STorM32 GUI to any routing component in a MAVLink ecosystem, such as an autopilot or an on-board companion computer, and to directly communicate with the STorM32 gimbal by using MAVLink Tunnel messages.

This mode of operation is enabled by checking the [MAVLink] checkbox next to the [Port] combo box.

This is extremely convenient when the STorM32 gimbal is permanently installed in a vehicle, as it allows us to configure the STorM32 gimbal without having to have direct access to its USB or UART ports. This also works via wireless telemetry links, and thus opens the option of e.g. tuning the gimbal during flight, and further unheard-of possibilities for controlling the gimbal during flight.

Comment: The passthrough communication is based on standard MAVLink, and thus should works for any MAVLink compatible autopilot.

This preliminary demo video demonstrates this feature:

Messages

The following MAVLink messages are supported:

MAVLINK_MSG_ID_HEARTBEAT (#0, 0x00)

See HEARTBEAT.

The emission of the heartbeat needs to be activated in the GUI via the Mavlink Configuration parameter. The heartbeat is emitted at 1 Hz, with the following values:

  • type: MAV_TYPE_GIMBAL (= 26)
  • autopilot: MAV_AUTOPILOT_INVALID (= 8)
  • base_mode: either 0 or MAV_MODE_FLAG_SAFETY_ARMED (= 0x80)
  • custom_mode: STATE value of the o323bgc firmware
  • system_status: either MAV_STATE_BOOT (= 1) or MAV_STATE_ACTIVE (= 4)

MAVLINK_MSG_ID_PARAM_REQUEST_READ (#20, 0x14)

See PARAM_REQUEST_READ.

MAVLINK_MSG_ID_PARAM_REQUEST_LIST (#21, 0x15)

See PARAM_REQUEST_LIST.

MAVLINK_MSG_ID_PARAM_VALUE (#22, 0x16)

See PARAM_VALUE.

MAVLINK_MSG_ID_PARAM_SET (#23, 0x17)

See PARAM_SET.

MAVLINK_MSG_ID_ATTITUDE (#30, 0x1E)

See ATTITUDE.

The emission of the attitude message with 2 Hz can be activated in the GUI via the Mavlink Configuration parameter, or by requesting a data stream using the MAV_CMD_SET_MESSAGE_INTERVAL command. The yaw angle is relative to the forward direction.

MAVLINK_MSG_ID_RC_CHANNLES (#65, 0x41)

See RC_CHANNELS.

When an ArduPilot autopilot (= MAV_AUTOPILOT_ARDUPILOTMEGA) is detected, streaming of this message by the autopilot is requested with req_stream_id = MAV_DATA_STREAM_RC_CHANNELS and req_message_rate = 10.

The parameter Virtual Channel Configuration needs to be set to “serial” for the values received by this message to become available for inputs as “Virtual-1” to “Virtual-16”.

MAVLINK_MSG_ID_COMMAND_LONG (#76, 0x4C)

See COMMAND_LONG.

Each command is acknowledged with a COMMAND_ACK message. The following commands are supported (parameter fields not mentioned are ignored): 

MAV_CMD_DO_SET_PARAMETER (#180, 0xB4)
* param1 = parameter index
* param2 = parameter value

MAV_CMD_DO_SET_SERVO (#183, 0xB7)
* param2 = pwm value (only 700...2300 accepted)

MAV_CMD_DO_DIGICAM_CONFIGURE (#202, 0xCA)
  is just there so that a COMMAND_ACK with MAV_CMD_ACK_OK is returned

MAV_CMD_DO_DIGICAM_CONTROL (#203, 0xCB)
* param5 = shot (0 = off, 1 = IRSHUTTER)

MAV_CMD_DO_MOUNT_CONFIGURE (#204, 0xCC)
* param1 = mount_mode (0 = MAV_MOUNT_MODE_RETRACT and 1 = MAV_MOUNT_MODE_NEUTRAL recenters the camera)

MAV_CMD_DO_MOUNT_CONTROL (#205, 0xCD)
* param1 = pitch, angle in degree (COMMENT: the sign is opposite to convention!)
* param2 = roll, angle in degree
* param3 = yaw, angle in degree (COMMENT: the sign is opposite to convention!)
* param7 = mount_mode (0 = MAV_MOUNT_MODE_RETRACT and 1 = MAV_MOUNT_MODE_NEUTRAL recenters the camera)

MAV_CMD_DO_SET_CAM_TRIGG_DIST(#206, 0xCE)
* param3 = trigger camera once immediately (0 = off, 1 = IRSHUTTER)

MAV_CMD_PREFLIGHT_STORAGE (#245, 0xF5)
* param1 = parameter storage
     0: restore parameter values from EEPROM
     1: store parameter values in EEPROM
     2: ignored, as it maybe harmful

MAV_CMD_PREFLIGHT_REBOOT_SHUTDOWN(#246, 0xF6)
* param4
     1: restart with full reset
     2: shut down motors

MAV_CMD_GET_MESSAGE_INTERVAL (#510, 0x01FE)
* param1 =  MAVLink message ID;

MAV_CMD_SET_MESSAGE_INTERVAL (#511, 0x01FF)
* param1 =  MAVLink message ID
* param2 = interval between two messages, in microseconds; set to -1 to disable
 
The periodic emission of one of these messages can be requested:
  * ATTITUDE (message id = 30)
  * MOUNT_STATUS (message id = 158)
  * MOUNT_ORIENTATION (message id = 265)
Stream rates of up to 100 Hz are supported. Note however that this can take a significant toll and may strain the STorM32's microcontroller capabilities.

MAV_CMD_REQUEST_MESSAGE (#512, 0x0200)
* param1 = message ID of the requested message  
     30: send ATTITUDE message
     148: send AUTOPILOT_VERSION message
     158: send MOUNT_STATUS message
     265: send MOUNT_ORIENTATION message
     300: send PROTOCOL_VERSION message
     700: send COMPONENT_INFORMATION message

MAV_CMD_REQUEST_PROTOCOL_VERSION (#519, 0x0207)
  send PROTOCOL_VERSION message 

MAV_CMD_REQUEST_AUTOPILOT_CAPABILITIES (#520, 0x0208)
  send AUTOPILOT_VERSION message

MAV_CMD_REQUEST_COMPONENT_INFORMATION (#700)
  send COMPONENT_INFORMATION message
  this is not official and work in progress, see https://github.com/mavlink/mavlink/issues/1133

MAVLINK_MSG_ID_COMMAND_ACK (#77, 0x4D)

See COMMAND_ACK.

MAVLINK_MSG_ID_AUTOPILOT_VERSION (#148, 0x94)

See AUTOPILOT_VERSION.

MAVLINK_MSG_ID_MOUNT_STATUS (#158, 0x9E)

ArduPilot specific message. See MOUNT_STATUS.

The emission of the mount status message with 2 Hz can be activated in the GUI via the Mavlink Configuration parameter, or by requesting a data stream using the MAV_CMD_SET_MESSAGE_INTERVAL command. The yaw angle is relative to the forward direction. The target is set to target_system = 0, target_component = 0.

MAVLINK_MSG_ID_AUTOPILOT_VERSION_REQUEST (#183, 0xB7)

ArduPilot specific message. See AUTOPILOT_VERSION_REQUEST.

MAVLINK_MSG_ID_MESSAGE_INTERVAL (#244, 0xF4)

See MESSAGE_INTERVAL.

MAVLINK_MSG_ID_STATUSTEXT (#253, 0xFD)

See STATUSTEXT.

This message is sent out after a PARAM_REQUEST_LIST has been served, and provides firmware and board type information.

MAVLINK_MSG_ID_MOUNT_ORIENTATION (#265, 0x109)

See MOUNT_ORIENTATION.

The emission of the mount orientation message with 2 Hz can be activated in the GUI via the Mavlink Configuration parameter, or by requesting a data stream using the MAV_CMD_SET_MESSAGE_INTERVAL command. The yaw angle is relative to the forward direction.

MAVLINK_MSG_ID_PROTOCOL_VERSION (#300, 0x12C)

See PROTOCOL_VERSION.

MAVLINK_MSG_ID_TUNNEL (#385, 0x181)

See TUNNEL.

Currently, for incoming messages the payload_type is 33333 and for outgoing messages it is 33334.

MAVLINK_MSG_ID_COMPONENT_INFORMATION (#700)

This is not official and work in progress, see https://github.com/mavlink/mavlink/issues/1133.

MAVLink Camera

The MAVLink Camera component is independent on the MAVLink Gimbal component, and can also be used then the MAVLink Gimbal component is disabled.

The setting in the Mavlink Camera parameter enables the MAVLink Camera component. In addition, MAVLink 2 must be enabled by setting Mavlink Version = “Mavlink2”; otherwise many functions of the MAVLink Camera component won't work properly.

The system ID of the MAVLink Camera component is determined by the parameter Mavlink System ID also used by the MAVLink Gimbal component. The component ID is determined by the Mavlink Camera setting: “Camera1” corresponds to MAV_COMP_ID_CAMERA (= 100), “Camera2” to MAV_COMP_ID_CAMERA2 (= 101), and so on.

The MAVLink Camera component supports the File Transfer Protocol micro service, which allows us to download the camera definition .xml files directly from the STorM32 gimbal controller.

The MAVLink Camera component is deeply related to the NT Camera. This means that it works in conjunction with the Camera Control function and associated parameters in the [GUI:Functions] tab.

Messages

The following MAVLink messages are supported:

MAVLINK_MSG_ID_HEARTBEAT (#0, 0x00)

See HEARTBEAT.

The emission of the heartbeat needs to be activated in the GUI via the Mavlink Camera parameter. The heartbeat is emitted at 1 Hz, with the following values:

  • type: MAV_TYPE_CAMERA (= 30)
  • autopilot: MAV_AUTOPILOT_INVALID (= 8)
  • base_mode: 0
  • custom_mode: 0
  • system_status: MAV_STATE_ACTIVE (= 4)

MAVLINK_MSG_ID_PARAM_REQUEST_READ (#20, 0x14)

See PARAM_REQUEST_READ.

MAVLINK_MSG_ID_PARAM_REQUEST_LIST (#21, 0x15)

See PARAM_REQUEST_LIST.

MAVLINK_MSG_ID_PARAM_VALUE (#22, 0x16)

See PARAM_VALUE.

MAVLINK_MSG_ID_PARAM_SET (#23, 0x17)

See PARAM_SET.

MAVLINK_MSG_ID_COMMAND_LONG (#76, 0x4C)

See COMMAND_LONG.

Each command is acknowledged with a COMMAND_ACK message. The following commands are supported (parameter fields not mentioned are ignored): 

MAV_CMD_REQUEST_MESSAGE (#512, 0x0200)
* param1 = message ID of the requested message  
     148: send AUTOPILOT_VERSION message
     259: send CAMERA_INFORMATION message
     260: send CAMERA_SETTINGS message
     261: send STORAGE_INFORMATION message
     262: send CAMERA_CAPTURE_STATUS message
     300: send PROTOCOL_VERSION message

MAV_CMD_REQUEST_PROTOCOL_VERSION (#519, 0x0207)
  send PROTOCOL_VERSION message 

MAV_CMD_REQUEST_AUTOPILOT_CAPABILITIES (#520, 0x0208)
  send AUTOPILOT_VERSION message

MAV_CMD_REQUEST_CAMERA_INFORMATION (#521, 0x0209)
* param1 = request camera capabilities
       1: send CAMERA_INFORMATION message

MAV_CMD_REQUEST_CAMERA_SETTINGS (#522, 0x020A)
  send CAMERA_SETTINGS message

MAV_CMD_REQUEST_STORAGE_INFORMATION (#525, 0x020D)
  send STORAGE_INFORMATION message

MAV_CMD_STORAGE_FORMAT (#526, 0x020E)
  returns COMMAND_ACK with MAV_CMD_ACK_DENIED

MAV_CMD_REQUEST_CAMERA_CAPTURE_STATUS (#527, 0x020F)
  send CAMERA_CAPTURE_STATUS message

MAV_CMD_RESET_CAMERA_SETTINGS (#529, 0x0211)
  returns COMMAND_ACK with MAV_CMD_ACK_DENIED

MAV_CMD_SET_CAMERA_MODE (#530, 0x0212)
* param2 = camera mode

MAV_CMD_SET_CAMERA_ZOOM (#531, 0x0213)
  returns COMMAND_ACK with MAV_CMD_ACK_DENIED

MAV_CMD_SET_CAMERA_FOCUS (#532, 0x0214)
  returns COMMAND_ACK with MAV_CMD_ACK_DENIED

MAV_CMD_IMAGE_START_CAPTURE (#2000, 0x07D0)
* param2 = desired elapsed time between two consecutive pictures (in seconds)
* param3 = total number of images to capture
* param4 = capture sequence number starting

MAV_CMD_IMAGE_STOP_CAPTURE (#2001, 0x07D18)
  stops capturing images

MAV_CMD_REQUEST_CAMERA_IMAGE_CAPTURE (#2002, 0x07D2)
  returns COMMAND_ACK with MAV_CMD_ACK_DENIED

MAV_CMD_VIDEO_START_CAPTURE (#2500, 0x09C4)
* param1 = video stream ID 
* param2 = frequency CAMERA_CAPTURE_STATUS messages should be sent while recording

MAV_CMD_VIDEO_STOP_CAPTURE (#2501, 0x09C5)
* param1 = video stream ID

MAVLINK_MSG_ID_COMMAND_ACK (#77, 0x4D)

See COMMAND_ACK.

MAVLINK_MSG_ID_FILE_TRANSFER_PROTOCOL (#110, 0x6E)

See FILE_TRANSFER_PROTOCOL.

The opcodes TerminateSession, ResetSessions, ListDirectory, OpenFileRO, ReadFile and CalcFileCRC32 are supported.

MAVLINK_MSG_ID_AUTOPILOT_VERSION (#148, 0x94)

See AUTOPILOT_VERSION.

MAVLINK_MSG_ID_AUTOPILOT_VERSION_REQUEST (#183, 0xB7)

ArduPilot specific message. See AUTOPILOT_VERSION_REQUEST.

MAVLINK_MSG_ID_CAMERA_INFORMATION (#259, 0x103)

See CAMERA_INFORMATION.

MAVLINK_MSG_ID_CAMERA_SETTINGS (#260, 0x104)

See CAMERA_SETTINGS.

MAVLINK_MSG_ID_STORAGE_INFORMATION (#261, 0x105)

See STORAGE_INFORMATION.

MAVLINK_MSG_ID_CAMERA_CAPTURE_STATUS (#262, 0x106)

See CAMERA_CAPTURE_STATUS.

MAVLINK_MSG_ID_CAMERA_IMAGE_CAPTURED (#263, 0x107)

See CAMERA_IMAGE_CAPTURED.

MAVLINK_MSG_ID_PROTOCOL_VERSION (#300, 0x12C)

See PROTOCOL_VERSION.

MAVLINK_MSG_ID_PARAM_EXT_REQUEST_READ (#320, 0x140)

See PARAM_EXT_REQUEST_READ.

MAVLINK_MSG_ID_PARAM_EXT_REQUEST_LIST (#321, 0x141)

See PARAM_EXT_REQUEST_LIST.

MAVLINK_MSG_ID_PARAM_EXT_VALUE (#322, 0x142)

See PARAM_EXT_VALUE.

MAVLINK_MSG_ID_PARAM_EXT_SET (#323, 0x143)

See PARAM_EXT_SET.

MAVLINK_MSG_ID_PARAM_EXT_ACK (#324, 0x144)

See PARAM_EXT_ACK.

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