Using STorM32 with ArduPilot

The information on this page refers to firmware v2.40 and BetaCopter v011, and higher.

The STorM32 gimbal controller can communicate with an ArduPilot flight controller via (i) a serial UART data line or (ii) the CAN bus using the UAVCAN protocol. The serial/UAVCAN communication allows for a much richer data transmission and accordingly richer set of features than possible with the traditional PWM connections. Examples are advanced control functions or the STorM32-Link. It also leads to a clean wiring.

If you just need the range of functionality possible with the standard tilt & pan control, then you don't need anything of the following, and you may stop reading here. Also, some of the features discussed below can be accomplished by workarounds. Decide yourself which approach fits your needs best. :)

STorM32 - ArduPilot Support

ArduPilot offers two mounts, which can be used with the STorM32 controller, the STorM32 Mavlink (MNT_TYPE = 4) and STorM32 Serial (MNT_TYPE = 5) mount types. For further details please visit ArduPilot Docs > Copter > Optional Hardware > Camera&Gimbals > SToRM32 Gimbal Controller. A good sum-up by lvale for the STorM32 Mavlink Mount is found here [1], and a workaround to access further STorM32 functions here [2].

Comment: Unfortunately, ArduPilot's gimbal support is partially flawed, which is true especially for its MAVLink mount. That is, some features you will find to work nicely, some others you will find to not work. There is nothing the STorM32 or any gimbal controller can do about it; it's ArduPilot. Please note that the STorM32 firmware author is not responsible for the implementation of these two mounts; again, it's ArduPilot.

The BetaCopter fork of ArduPilot additionally offers the STorM32 Native (MNT_TYPE = 83) mount type, and Serial UAVCAN Tunnel ports for communicating via the CAN bus instead of a serial bus. These additions were created and are maintained by the STorM32 firmware developer and provide the best range of functions.

A comparison of the different techniques to connect the STorM32 controller with the flight controller is given in the following feature matrix.

Feature Matrix

(to the best of the authors knowledge)

Feature	PWM	STorM32 Mavlink	STorM32 Serial	STorM32 Native
Gimbal Angle Control	x	x (?)	x	x
Solo Smart Shots	x	-	-	x
MAV_MOUNT_STATUS message	-	x (1)	x (2)	x
Camera Trigger	x	x (?)	-	x
Gimbal Point in MP	-	x (?)	x	x
Video on/off	-	-	-	x
RC Targeting relative/absolute	-	-	-	x
360° Gimbal with Free Look	-	-	-	x
STorM32 Functions	-	-	-	x
STorM32 Scripts	-	-	-	x
STorM32-Link: Horizon Drift Comp.	-	-	-	x (3)
STorM32-Link: Yaw Drift Comp.	-	-	-	x (3)
Passthrough Configuration	-	-	-	x

(?) May or may not work properly in the latest ArduPilot releases, see the comment in the introduction. Please check with the ArduPilot community.

(1) The message reports the last set point, not the actual gimbal/camera orientation.

(2) Works only for deprecated v0.xx firmwares.

(3) Works only for T-STorM32 gimbals.

BetaCopter

Some modifications to the ArduCopter firmware were made and the result called BetaCopter, which provides simply the best support of STorM32 gimbals.

Comments:

• If you are satisfied with ArduPilot's gimbal support then there is really no need to use BetaCopter. However, if you want to make best use of the STorM32's features and capabilities then you want to chose BetaCopter.
• Before using BetaCopter it is strongly recommended to first install the original ArduCopter firmware and get the copter flying flawlessly with it, and only then to install BetaCopter.

BetaCopter comes in two variants:

• The 'u' version ('u' for UC4H) is derived from Copter 3.6.0, and includes the full set of additions, including all UAVCAN and UC4H additions.
• The 's' version ('s' for serial) is also derived from Copter 3.6.0. It includes all STorM32 additions, but does not include any of the UAVCAN or UC4H additions. It is a very straight forward, minimal intrusive extension of Copter-3.6.0, and "guaranteed" to work as reliably as Copter 3.6.0.

The latest versions of BetaCopter and the STorM32 firmware can be downloaded from here: Downloads.

In order to establish a working communication between the STorM32 and the flight controller, parameters on both sides, BetaCopter and STorM32, need to be adjusted, as described in the following.

The BetaCopter fork implements the STorM32 Native mount type, which handles all of the following. For the BetaCopter 's' version this means, that if the STorM32 Native mount is not activated, it will behave exactly like the original Copter-3.6 firmware, with no side effects.

STorM32 Native via UART Port

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The STorM32 board needs to be connected via one of its UART ports or the USB port to one of the UART ports on the ArduPilot flight controller, and these settings be made:

Settings in BetaCopter:

• MNT_TYPE = 83
• SERIALx_PROTOCOL = 83
• SERIALx_BAUD = 115

Settings in STorM32:

• Mavlink Configuration = “no heartbeat”

With the mount activated, you should notice:

• All ArduCopter mount features such as gimbal control, POI, follow me, smart shots, and so on, are working.
• All ArduCopter camera features are working. That is, whenever a certain path of actions (Mavlink, receiver, mission, UAVCAN, ...) lets ArduCopter want to take a picture, the STorM32 controller will know and activate its camera functions.
• In the Message box of MissonPlanner "STorM32 ..." messages will appear.
• The STorM32-Link, providing horizon drift and yaw drift compensation, and additional features, is present.

Comment: The default baudrate of the STorM32 serial ports is 115200 bps, hence in ArduPilot SERIALx_BAUD has to be set to 115. However, other baudrates can be configured; for e.g. 230400 bps one sets the STorM32 parameter Uart Baudrate to “230400” and the ArduPilot parameter SERIALx_BAUD to 230.

STorM32 Native via UAVCAN

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The STorM32 can also be connected via the CAN bus to the ArduPilot flight controller. The communication is then established by using one of the serial UAVCAN tunnels (SERIALTNLx) in BetaCopter, instead of a UART (SERIALx) port. Function-wise this configuration is identical to using a serial port, except of course that the data communication is now via the CAN bus using the UAVCAN protocol. The required settings are:

Settings in BetaCopter:

• MNT_TYPE = 83
• SERIALTNLx_PROT = 83
• SERIALTNLx_CH_ID = 71
• SERIALTNLx_BAUD = 115 (is actually irrelevant in this case)

Settings in STorM32:

• Mavlink Configuration = “no heartbeat”
• Can Configuration = “uavcan”
• Uavcan Node ID = “71”

The CAN bus of the flight controller must be configured in addition. This requires that additional parameters in the flight controller's CAN section must be set appropriately. Typical settings could be:

• CAN_D1_PROTOCOL = 1
• CAN_P1_BITRATE = 1000000
• CAN_P1_DRIVER = 1

Please consult the ArduPilot Docs for further information.

Comment: The channel ID used by BetaCopter and STorM32 must be identical. The STorM32's channel ID is identical to its UAVCAN node ID, which by default is 71. Dynamic node allocation is not supported. The range of allowed IDs is restricted to 11 - 124. The STorM32 board needs to be reset for a change to become effective.

The details of the STorM32's UAVCAN support, including its configuration, are described in the article UAVCAN.

The 'STorM32 Native via UAVCAN' option obviously requires using the 'full' version of BetaCopter, and is not available with the 's' version.

STorM32-Link

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Parameter in STorM32:

• STorM32Link Configuration = “v1”

With MNT_TYPE = 83 also the STorM32-Link is activated (for details see STorM32-Link). That is, in addition to the 'conventional' data also the data required for the functioning of the STorM32-Link are emitted by the flight controller. The parameter STorM32Link Configuration set to “v1” makes the STorM32 using them. In the STorM32 GUI, specifically the [GUI:Dashboard] and/or the [GUI:Data Display], you should note that the STorM32-Link field goes to INUSE and OK.

Comment: If only the 'conventional' data but not the STorM32-Link data are received by the STorM32 controller, then an ISPRESENT and/or OK will be displayed to indicate that a working link has been established between STorM32 and BetaCopter, and that the 'conventional' control functions are all working. The INUSE flag will not appear, which indicates that the STorM32-Link, i.e., the horizon and yaw drift compensation feature, is not active.

Comment: The STorM32-Link is available only for T-STorM32 gimbals, but not the conventional STorM32 NT gimbals.

STorM32: Virtual Channel Configuration

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Parameter in STorM32:

• Virtual Channel Configuration = “serial”

With this setting, all STorM32 functions can be invoked by selecting any of the “Virtual-1” - “Virtual-16” input channels, exactly as one would do if the STorM32 controller 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, and it is the users responsibility to avoid that. For instance, if the ArduPilot mount is activated and is in Rc Targeting mode, and e.g. Rc Pitch Control is set to a virtual input channel, then the gimbal may move in funny ways since it may receive the transmitter stick information from both the ArduPilot mount and the receiver. In contrast, if the ArduPilot mount is in GPS or ROI Targeting mode, then one gets "free look", which is useful and quite cool actually. As said, all this is exactly as if the receiver would be directly connected to the STorM32 controller on its RC ports.

RC Targeting

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Parameter in BetaCopter:

• MNT_STRM_BM

The BetaCopter parameter MNT_STRM_BM, which is a bit mask, allows us to enable/disable various functions. Especially the behavior of the RC Targeting mode can be modified. By setting the 1-st bit of MNT_STRM_BM, that is by adding +1 to the current value, the RC Targeting is determined now by the STorM32 parameters in the [GUI:Rc Inputs] tab. This especially allows us to set a relative mode.

Passthru Configuration

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Parameter in BetaCopter:

• MNT_STRM_PTSER

This feature allows you to connect the STorM32 GUI to the USB port of an ArduPilot flight controller, or in fact to any of its serial ports, or the UAVCAN bus, and to directly communicate with the STorM32 gimbal. This is extremely convennient for configuring STorM32 gimbals when e.g. installed permanently in the flight vehicle. This also works via a wireless telemetry link, and thus opens the option of e.g. tuning the gimbal during flight, and further unheard of possibilities for controlling the gimbal during flight.

These two video demonstrate this feature, and also explain the setup:

Comment: In BetaCopter v0.10 and higher, by default the passthru communication is disabled when the flight controller is armed, and e.g. in-flight configuration would not work. This protection can be disabled by setting the 7-th bit in the MNT_STRM_BM parameter, by adding +64 to its value.

Testing the Connection

The serial/UAVCAN connection can be tested in several ways. The following tests do not require that the copter is completely built, and do not require that the copter is armed.

• 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, PRESENT or a similar positive message.

• Message box in MissonPlanner: In the message box several messages related to the STorM32 should appear. In particular, a message like "STorM32 v2.40 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 finished initialization and entered NORMAL mode.

• 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 ArduPilot mount in RC Targeting mode (which should be the default setting), the camera can be moved with the transmitter sticks.

• Sniffing the communication: One of course can sniff directly what is going on on the communication data lines. This is especially helpful when using CAN/UAVCAN. You when need a SLCAN adapter, e.g., the UC4H SLCAN adapter.

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:

Settings in ArduPilot:

• MNT_STAB_ROLL = 0
• MNT_STAB_TILT = 1