Using STorM32 with ArduPilot

The STorM32 gimbal controller can communicate with an ArduPilot flight controller via (i) a serial data line or (ii) the CAN bus using UAVCAN. The serial/UAVCAN communication allows for a much richer data transmission 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/UAVCAN communication allows us to control the orientation of the gimbal, with higher precision than possible with the standard inputs, and gives access to all other features of the STorM32 controller, such as 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 by a ground station or OSD. Advanced operation modes, which in addition involves the flight controller, ground station, companion computer, or other electronics, such as follow me or object tracking, also fall into that category.
• Improved stabilization: In addition, the serial/UAVCAN communication is used to transfer dedicated data from the flight controller to the STorM32 controller, which helps in achieving better stabilization, and hence better videos. For instance, yaw drift can be corrected, horizon shifts in high-speed turns removed, or smoother pans achieved. This part of the serial/UAVCAN 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.

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, many of the things below could be accomplished by workarounds. Decide yourself which approach fits your needs best. :)

STorM32 - ArduPilot Support

Four modes of operation are available:

STorM32 Mavlink

• MOUNT_TYPE = 4
• SERIAL_PROTOCOL = 1
• 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. A good sum-up by lvale is found here [1], and a workaround to access further STorM32 functions here [2].

STorM32 Serial

• MOUNT_TYPE = 5 (the arducopter documentation is wrong here)
• SERIAL_PROTOCOL = 1
• 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 UAVCAN

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

STorM32 Native

• MOUNT_TYPE = 84
• SERIAL_PROTOCOL = 84
• STorM32 heartbeat must be deactivated, Mavlink Configuration = “no heartbeat”
• available only in BetaCopter

The STorM32 UAVCAN and STorM32 Native modes are essentially identical, except that the data communication in the former case is via the CAN bus using the UAVCAN protocol, and in the latter case via the selected serial port.

The remainder of this wiki page is devoted exclusively to describing the STorM32 UAVCAN/Native modes; the STorM32 UAVCAN mode is chosen exemplarily.

Feature Matrix

Feature	STorM32 Mavlink	STorM32 Serial	STorM32 UAVCAN
Gimbal Angle Control	x	x	x
Camera Trigger	x (?)	-	x
MAV_MOUNT_STATUS message	x	x	x
Video on/off	-	-	x
Extended Gimbal Angle Control	-	-	x
360° Gimbal with Free Look	-	-	x
STorM32 Functions	-	-	x
STorM32 Scripts	-	-	x
STorM32-Link	-	-	x

BetaCopter

I made some modification to ArduCopter (currently AC3.4-rc5), yielding BetaCopter. However, unless the STorM32-specific features are 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, or higher. You can download the latest versions from here: Downloads.

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 should be set to 115, but is in fact ignored; the baudrate will always be configured to 115200 bps. 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, including all those that follow.

Comment: Setting MNT_TYPE is not required, and its value is in fact ignored. This makes it easy to configure for the STorM32 native connection.

ArduCopter: STORM Parameters

BetaCopter introduces some new parameters, which are collected under the STORM header.

• 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.

• STORM_RCIN_DZ: Sets deadbands for the native STorM32 mount, when STORM_RC_TRGT is enabled.

• STORM_DIS_MASK: Bitmask to disable specific features by setting a corresponding bit.
  It sometimes can be useful to disable a particular function. Bits 1: disable mount, 2: disable camera trigger, 4: disable transmitter passthrough.

• STORM_FS_HOVER: Enables BetaCopter's better radio failsafe, 0:disabled or 1:enabled.
  For some receivers ArduPilot doesn't provide a satisfying failsafe handling, which easily leads to potentially harmful flying conditions. That's specifically so when using a Spektrum satellite. This is known for long but still not addressed; when you're using a Spektrum satellite it is recommended to enable that feature.

STorM32: Virtual Channel Configuration = serial

In the STorM32 GUI the Virtual Channel Configuration parameter can be set to “serial”, with this effect:

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, 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 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 also have activated the STorM32-Link (if you want to know in detail what the STorM32-Link is about, please see [3]). In the STorM32 GUI, specifically the [GUI:Dashboard] and/or [GUI:Data Display], you should thus note that the STorM32-Link field goes ON.

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

Testing the Serial Connection

The serial 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.

• Message box in MissonPlanner: In the message box several messages related to the STorM32 should appear. In particular, a message like "STorM32 v2.11e 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.

• 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 or a similar positive message.

• 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 turned with the transmitter sticks.

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