Using STorM32 with ArduPilot

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The STorM32 gimbal controller can communicate with an ArduPilot flight controller via a serial data line. The serial communication allows for a much richer data exchange and accordingly richer set of features than possible with the traditional PWM connections. It also leads to a clean wiring.

Two aspects of the communication should be distinguished:

  • Control of the gimbal: The serial communication allows us to access all features of the STorM32 controller, such as those for controlling the orientation of the gimbal, triggering a camera, executing on-board scripts, and so on. It also allows the STorM32 to feed back information to the flight controller and the ground station, such as the actual camera orientation, which can be displayed e.g. by the ground station or an OSD. Advanced modes, provided by the flight controller and/or ground station, such a follow me, object tracking, and so on, also belong to that aspect.
  • Improved stabilization: In addition, the serial communication can be used to transfer data from the flight controller to the STorM32, which helps it to achieve a better stabilization performance. For instance, yaw drift can be corrected or horizon shifts in high-speed turns removed. This part of the serial communication is called the STorM32 Link.

This article is mostly concerned with the first aspect, also because the STorM32 Link is not yet fully developed.

STorM32 - ArduPilot Support

Three modes of operation are currently available:

STorM32 Mavlink

  • SERIAL_PROTOCOL = 1
  • MOUNT_TYPE = 4
  • STorM32 heartbeat must be activated, Mavlink Configuration = “emit heartbeat” or higher
  • available in ArduPilot and BetaCopter

For further details please visit ArduPilot Docs > Copter > Optional Hardware > Camera&Gimbals > SToRM32 Gimbal Controller.

Comment: When the STorM32's Mavlink System ID is configured to be different from that of the autopilot, e.g. to the default value “71”, when the mount works, but the gimbal point does not. Reversely, when the STorM32 is configured as component by setting its Mavlink System ID equal to that of the autopilot, usually “1”, when the mount does not work, but the gimbal point does. Camera trigger works partially.

STorM32 serial

  • SERIAL_PROTOCOL = 8
  • MOUNT_TYPE = 5 (the arducopter docu is wrong here)
  • STorM32 heartbeat must be deactivated, Mavlink Configuration = “no heartbeat”
  • available in ArduPilot and BetaCopter

For further details please visit ArduPilot Docs > Copter > Optional Hardware > Camera&Gimbals > SToRM32 Gimbal Controller.

STorM32 native

  • SERIAL_PROTOCOL = 83
  • MOUNT_TYPE is irrelevant
  • STorM32 heartbeat must be deactivated, Mavlink Configuration = “no heartbeat”
  • available only in BetaCopter

The remainder of this wiki page is devoted exclusively to describing the STorM32 native mode.

Feature Matrix

Feature STorM32 Mavlink STorM32 serial STorM32 native
Gimbal Angle Control x x x
Camera Trigger x - x
MAV_MOUNT_STATUS message - x x
Video on/off - - x
Extended Gimbal Angle Control - - x
360° Gimbal with Free Look - - x
STorM32 Functions - - x
STorM32 Scripts - - x
Transmitter Passthrough - - x
STorM32-Link - - x

BetaCopter 3.4

I made some modification to ArduCopter AC3.4 (currently rc2), yielding BetaCopter. However, unless the STorM32-specific features are not activated by a "secret key" 83, BetaCopter will - to the best of my knowledge - behave exactly like the original code. This means that - to the best of my knowledge - there is no additional risk in using BetaCopter instead of ArduCopter.

For the following you need betacopter 3.4rc2 v017 and o323bgc v2.11e. You can download them here:

On the STorM32, the Mavlink Configuration parameter must be set to “no heartbeat”.

The following settings or parameter fields are available. The features involve settings on both the BetaCopter and STorM32 side.

ArduCopter: SERIALx_PROTOCOL = 83

As serial protocol you may choose 83, which activates BetaCopter's native STorM32 protocol. SERIALx_BAUD must be set to 115. You should then notice this:

  • All ArduCopter camera features are working. That is, whenever a certain path of actions (Mavlink, receiver, mission,...) lets ArduCopter think it wants to take a picture, the STorM32 will know and act.
  • All ArduCopter mount features are working. Well, that's mostly exactly what you get also with the other modes of operation, e.g. when using the Mavlink connection with ArduPilot. One enhancement of the 83 mode is however that also the Mavlink MAV_MOUNT_STATUS message is emitted, so that in e.g. MissionPlaner the camera orientation can be read off. Furthermore, see the next parameters.
  • In the Message box of MissonPlanner "STorM32 ..." messages will appear.

Setting SERIALx_PROTOCOL = 83 is mandatory for any of the STorM32-specific features to work. That is, also the other features below won't work without that setting.

Comment: Setting MNT_TYPE is not required anymore, in fact with the serial protocol set to 83 the MNT_TYPE parameter is ignored. This makes it easy to configure for the STorM32 native connection.

ArduCopter: STORM Parameters

BetaCopter introduces some new parameters, which are collect under the STORM section.

  • STORM_ARMCHECKS: Enables pre-arm and arm checks, 0:disabled or 1:enabled.
    When enabled, this checks if the gimbal has been initialized, i.e. is in NORMAL state. Otherwise arming the copter is denied. In future this option will in addition allow us to extend the STorM32's initialization procedure to until the copter is ready to go, which the STorM32 gimbal controller will use to improve its calibration, and thus stabilization performance.
  • STORM_HAS_PAN: Allows to set the has_pan_control flag of the native STorM32 mount to 0:false or 1:true.
    It is not totally clear to me what this flag does (for the other mounts it is set to false). From the code I speculate that when false the copter will yaw along with a yaw command to the gimbal, while when true the copter isn't affected by a yawing mount. If so, the latter would enable a free 360° panning independent on the copter as expected for 360° gimbals (see e.g. digaus' tracking work). Anyway, whatever this flag does, it will be interesting to figure it out.
  • STORM_RC_TRGT: Allows to modify the behavior of the native STorM32 mount in the RC Targeting mode.
    A value of 0 sets it to the standard ArduPilot behavior, as you know it. In this setting, the camera motion is determined by the various MNT parameters. When set to 1, in contrast, the standard STorM32 behavior is obtained. Here, the camera motion is determined by the STorM32's Rc Input parameter fields. That is, the camera responds to transmitter inputs in exactly the same way as you know it for the STorM32. I guess, after having gotten used to it, most will prefer this operation mode. It is also somewhat more robust against rc failsafes.

STorM32: Virtual Channel Configuration = serial

The STorM32's Virtual Channel Configuration parameter can be set to “serial”. This enables this feature:

All STorM32 functions can be invoked by selecting a “Virtual-1” - “Virtual-16” input channel, as if the STorM32 would be directly connected to the receiver. This allows doing many useful things, such as activating a script or triggering video on/off from the transmitter. It however also allows doing nonsense, e.g. if the ArduCopter mount is activated and is in Rc Targeting mode, and a RC input control, e.g. Rc Pitch, is set to a virtual input channel, then the gimbal will move in funny ways since it receives the transmitter stick information from two different sides. In contrast, if the ArduCopter mount is in GPS or ROI Targeting mode, when one gets "free look", which is useful and quite cool actually. As said, all that is exactly as if the receiver would be directly connected to the STorM32 on its RC ports.

STorM32-Link

With SERIALx_PROTOCOL = 83 you should also note that in the STorM32 GUI, specifically the [GUI:Dashboard] and/or [GUI:Data Display], the STorM32-Link field goes ON. If you want to know what the STorM32-Link is about, please see http://www.rcgroups.com/forums/showthread.php?t=2395475. In short, the STorM32-Link transmits data from the flight controller to the STorM32 controller, which allows for an improved stabilization performance such as a better horizon stability, lower yaw drift, or IMU calibration.

The main parts of the STorM32-Link functionality are actually not yet implemented in the STorM32, this will take some more time. However, as evidenced by STorM32-Link field going ON, the data exchange is established, which can be considered a crucial milestone.

Testing the Serial Connection

The serial connection can be tested in several ways. The following tests do not require that the copter build is completed, and do not require that the copter is armed.

  • Message box in MissonPlanner: In the message box several messages related to the STorM32 should appear. In particular, a message like "STorM32 v2.10e nt v1.30 F103RC" informing about the STorM32 firmware version should be visible. Also, a message "STorM32 in NORMAL mode" should occur when the gimbal has initialized.
  • STorM32-Link field in the STorM32 GUI: The [GUI:Dashboard] and [GUI:Data Display] each have a field which is related to the STorM32-Link. They should display OK.
  • Trigger Camera NOW: In MissionPlanner the camera can be triggered by a right-mouse-click dropdown menu in the Flight Data map. On the STorM32 side the camera trigger can be easily tested by connecting a visible-light LED (red, green, blue, not IR) to the #IR port.
  • Gimbal RC Targeting: With the mount in RC Targeting mode (which should be the default setting), the camera can be turned with the transmitter sticks. This requires MNT_TYPE = 83 to be set.

Gimbal Point

MissionPlanner supports what it calls a gimbal point. It is a blue point icon on the map, which indicates the estimated position at which the gimbal is looking at (see also e.g. https://github.com/ArduPilot/MissionPlanner/issues/1323). In order to activate it, the following ArduPilot parameters must be set:

  • MNT_STAB_ROLL = 0
  • MNT_STAB_TILT = 1
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