Setup Guide SK 540 Flybarless System - Skookum …©2012 Skookum Robotics Ltd. 2 Congratulation on buying the Skookum Robotics SK 540 Flybarless System! The SK 540 is a high performance

Setup Guide SK 540 Flybarless System

Rev. 1.0 April 2012

©2012 Skookum Robotics

©2012 Skookum Robotics Ltd. 1

Safety Warnings .......................................................................................................................................................................................... 3

Getting Started............................................................................................................................................................................................ 4

Installing the SK 540’s Software.............................................................................................................................................................. 4

Modes & LED Indicator States ................................................................................................................................................................ 5

Connecting the SK 540 ................................................................................................................................................................................ 8

Connecting Servos Using a 3-Point Swashplate...................................................................................................................................... 9

Connecting Servos Using a 4-Point Swashplate.................................................................................................................................... 10

Connecting Satellite (Remote) Receivers.............................................................................................................................................. 11

Connecting S Bus Receivers .................................................................................................................................................................. 13

Connecting PPM Receivers ................................................................................................................................................................... 15

Connecting Traditional Receivers ......................................................................................................................................................... 17

Connecting RPM Sensors ...................................................................................................................................................................... 20

Mounting the SK 540 ................................................................................................................................................................................ 21


Congratulation on buying the Skookum Robotics SK 540 Flybarless System! The SK 540 is a high performance flybarless controller,

including an optional governor and flight logging capabilities. The SK 540 also features a user interface to help in setting up and

tuning the unit, and Setup Wizards to walk you through the setup steps within the interface.

Your SK-540’s box contains:

1 SK 540

1 USB Cable

1 Decal Sheet

Mounting Tape


Safety Warnings

RC helicopters are not toys and have the potential to cause serious personal injury and propter damage. Use of

this gyro places a flight control computer (the SK720) between the radio receiver and the servos that position the

helicopter’s controls. Loss of control of the helicopter may result if the SK720 is mistuned or set up incorrectly.

WARNING: Stand clear! Always test fly in an area away from spectators and keep yourself at a safe distance

when flying the helicopter, especially after any change in the gyro’s setup or tuning. DO NOT stand closer than

10m (30 feet) from the helicopter during test hovers or any other flying. Keep bystanders clear of the flight area

at all times.

WARNING: Always “safe” the motor before you use the PC setup software or SK-LCD terminal to set up or tune

your SK-720. Basic safety practice is to kill the engine on a nitro RC helicopter, or disconnect the motor or main

battery on an electric RC helicopter, whenever the heli is behind the flight line, or is being adjusted in any way.


Getting Started

Installing the SK 540’s Software

The SK540’s setup software is available online in the Updates section of our website (www.skookumrobotics.com). Download the

SK540 installer package, and find the file “SK_setup.exe.” Open this file and follow the instructions on the installation wizard. Once

this is installed, you’re ready to begin the Setup Wizards and the setup of your SK 540.

If the SK 540’s software cannot open, make sure you are running the latest version of Windows .NET Runtime. See Microsoft’s

website for the most recent edition. You can find the most up to date version of the SK-720’s software on the Updates page of our

website.


Modes & LED Indicator States

The SK 540’s LED indicates the gyro’s current function. The table below outlines the LED’s patterns for each function:

LED State Meaning

Slow Green Setup Mode

Fast Green USB File Transfer

Solid Red Flight Mode – Initializing

Solid Green Flight Mode – Ready to Fly

Flashing Red Error State

Alternating Red / Green Firmware Updating – Do Not Disturb

The SK 540 switches to Setup Mode when it is connected to a PC via the USB cable or to the LCD terminal. In this mode the SK 540

provides control mixing, but no stabilizing action – this allows you to complete mechanical setup and servo trimming.

When initializing, the SK 540 needs to be completely still for several seconds. The SK 540 will fly without being properly initialized,

but it will not be in trim – make sure you have a solid green LED before flying!

The most common causes for the flashing red error state are:

• The cyclic stick wasn’t centred during gyro initialization in flight mode

• Your helicopter has onboard electrical system voltage problems.

• The SK 540 is too hot or too cold

In most cases resetting the SK 540 will clear the error state.


Below is the SK 540 software interface, designed and developed for the setup and tuning of your SK 540.

The SK 540’s Setup Wizards provide step by step instructions on using the interface and setting up your helicopter. They must be

completed before flying your helicopter.

Figure 1 - The SK 540 Software Interface


Following the Setup Wizards ensures proper setup of the SK 540 and your helicopter. You must complete all 4 of the Setup

Wizards before spooling up your heli. If you’re unsure about how to proceed in any of the setup wizards, video walkthroughs of

the wizards (and more!) are available on our YouTube channel at: http://www.youtube.com/user/SkookumRobotics. More

information and troubleshooting tips are available at www.skookumrobotics.com/wiki, and you can reach the Skookum Robotics

team by emailing us at:

.

Figure 2 – The SK 540’s Setup Wizards


Connecting the SK 540 Your helicopter’s servos get connected midway through the Initial Setup Wizard. DO NOT connect them until you reach that step in

the Wizard. Cables are connected to the SK 540 with the signal wire on the top (closest to the SK 540 label), positive in the middle

and ground on the bottom. On electric helis, the SK 540 is powered via the ESC. Nitro helis require the SK 540 to be powered by a

battery or BEC connected to any open port on the SK 540.

The SK 540’s servo bus has 9 ports on the side of the unit. The table below outlines the abbreviations and names for each port.

Port Full Name

EX-LED External LED

IO-C Input/Output C

IO-B Input/Output B

IO-A(T) Input/Output A/Throttle

SW-A Swash - Aft

SW-L Swash - Left

SW-R Swash - Right

SW-C Swash - Centre

Tail Tail


Connecting Servos Using a 3-Point Swashplate

The diagrams below outline the servo connections to the SK 540 using 3- and 4-point swashplates. When using a three point

swashplate, you can mount the centre servo in front or behind the left and right servos.

Figure 3 - The SK540 connected to a 3-point swashplate.


Connecting Servos Using a 4-Point Swashplate

When using a four point swashplate, the centre servo gets mounted at the front of the heli, and the aft servo is mounted at the

back.

Figure 4 - The SK540 connected to a 4-point swashplate.


Connecting Satellite (Remote) Receivers

Your SK 540 can be used with Spektrum, JR, Futaba SBUS and traditional receivers. Satellite receivers are connected to the SAT RX

ports at the side of the SK 540.

Using two Sat RXs is not necessary, though we recommend using a second satellite for larger helicopters. If you use a second Sat RX,

make sure that the antennae point in different directions to the other RX to improve signal diversity.

Figure 5 – Satellite (remote) receivers are connected to the ports at the bottom of the etched label.


Spektrum/JR Sats are the default setting for receivers in the SK 540’s interface. Newer Spektrum TXs (DX7se and newer) use 2048

resolution, older (DX-7, DX-6 and older) use 1024.

Figure 6 - Be sure to specify your Spektrum/JR receiver's resolution.


Connecting S Bus Receivers

SBUS receivers are connected to the IO-B port using a jumper. Unlike the SK 720, the 540 does not need an SBUS adapter.

If you are running servos directly from your SBUS receiver, run a power-only jumper cable (red and black wires only) to your receiver

along with the SBUS adapter. Power can be provided from an open port on the SK 540 or a BEC. This will provide enough power for

the receiver and servos. Figure 7 - S Bus receivers are connected to the IO-B port with a jumper cable


By default, the receiver in the SK 540’s software is set to Spektrum/JR - make sure to specify Futaba SBUS in the Control Tab of the

SK 540’s software.

Figure 8 - When using an S Bus RX, be sure to specify that receiver type in the Control tab.


Connecting PPM Receivers

PPM Receivers are connected to the SK 540 via the IO/B port. If you are using a PPM Receiver, make sure to specify that type of RX

in the SK 540 software. Figure 9 - PPM Receivers are connected to the IO-B port.


By default, the receiver in the SK 540’s software is set to Spektrum/JR - make sure to specify PPM Receivers in the Control tab of the

SK 540’s software. Figure 10 (below) demonstrates.

Figure 10 – When using a PPM RX, be sure to specify that receiver type in the Control tab.


Connecting Traditional Receivers

Traditional receivers are connected to the EX-LED and IO ports using the SK 540-specific Traditional RX cable kit. Note that the ESC

or throttle servo is connected directly to the receiver rather than the IO-A(T) port.

Figure 11 - Connecting the SK 540 to a traditional receiver


The diagram below displays the pin placement of the SK-CBL on the SK-720. RPM sensors are connected to the IO-C port regardless

of the SK 720’s setup. As a result, RPM sensors cannot be used along with a Traditional RX setup.

Figure 12 - Pin placement for connecting the SK 540 to a traditional receiver.


By default, the receiver in the SK 540’s software is set to Spektrum/JR - make sure to specify Traditional Receiver in the Control Tab

of the SK 540’s software. Figure 13 (below) demonstrates.

Figure 13 - When using a traditional receiver, be sure to specify that receiver type in the Control tab.


Connecting RPM Sensors

RPM sensors are always connected to the IO-C port. Since IO-C is occupied if you are using a traditional receiver, the governor is not

available when using a traditional receiver. Be sure to set the governor to Electric or Nitro in the SK540’s setup software.

Figure 14 - RPM sensors are connected to IO-C, even when using the Power Bus as well.

The SK 540 is compatible with all phase and crankcase sensors as of the release of this manual, including Hyperion and Eagle Tree

sensors. However, if you use an Eagle Tree sensor you must swap the red and black wires.

Most sensors will be damaged by voltage higher than 5.5V. If you are using HV servos on your heli, the SK 540 will output the higher

voltage to the RPM sensor. Using a step-down to the sensor will be necessary if you use HV servos.


Mounting the SK 540 The SK 540 can be mounted in a variety of orientations. There are only two requirements for mounting the SK540:

1. The unit’s etched label must be facing up or down

2. The unit must be mounted with its edges square to the helicopter’s frame.

Below is a diagram outlining the possible orientations of the SK 540:

Figure 15 – Possible mounting orientations of the SK540


The alignment of your SK 540 is very important. If your SK 540 is even a few degrees out of alignment problems can occur with

tuning the unit. A few degrees of misalignment are measured as a difference of over 2mm or 1/16” between the two ends of the

unit compared to the helicopter’s frame. Handling and control issues are often the result of improper alignment, so make sure that

all the SK 540s edges are 90° to the helicopter’s frame. Proper alignment is shown below.

Figure 16 - Correct alignment of the SK540.


The SK 540 can also be mounted in a variety of positions on your heli. Mounting the 540 close to your heli’s centre of gravity will

give the best performance, but you can mount the unit away from the centre of gravity as long as the location you choose meets the

orientation requirements.

Figure 17 - The SK540 mounted near the helicopter's tail boom.


The SK 540 can be secured to your heli using the included mounting tape. You can also mount the SK 540 using PU gel, 3M double-

sided foam tape or grey mounting foam, but it is not necessary to take extreme steps to isolate the SK 540 from vibrations. The

SK540 can be mounted with thin tape as well.

Figure 18 – When using a strap to secure the SK540, be sure not to strap it too tightly.


The SK540 can be used with the SKPB1 and SKPB2 Power Bus. However, the SK540 does not have the same requirements as the

SK720. The SK540 does not need the Power Bus to reduce vibrations.

BUS-A and BUS-B send the throttle, swash and tail servo signals from the SK 540 to the servos and ESC. These are the only two

connections you need to use the Power Bus. S Bus and PPM receivers, RPM sensors and external LEDs can all be connected directly

to the SK540 without using the Power Bus.

Figure 19 - The SK540 connected to the Power Bus. Note: the Power Bus ports are reversed for clarity.


The diagram below shows the pin placement on the SK540 when using the Power Bus. The orange wires shown may be white,

depending on your servo wires.

Figure 20 - Connecting the SK540 to the Power Bus

Documents

Setup Guide SK 540 Flybarless System - Skookum …©2012 Skookum Robotics Ltd. 2 Congratulation on buying the Skookum Robotics SK 540 Flybarless System! The SK 540 is a high performance