cyber® reaction wheel 2
Project planning guideDoc. no.: 5022-D060586

Revision: 02

Project planning guide
Revision history

cyber® reaction wheel 2

Revision

Date

Comment

Chapter

01

12/08/2021

New Version

All

Technical support
In the event of technical questions, contact the following address:
WITTENSTEIN cyber motor GmbH
Sales
Walter-Wittenstein-Str. 1
D-97999 Igersheim
Tel.: +49 (0) 79 31 / 493-15800
Fax: +49 (0) 79 31 / 493-10905
Email: info@wittenstein-cyber-motor.de
If you have any questions about installation, startup or optimization, please contact our support
hotline.
WITTENSTEIN cyber motor GmbH support hotline
Tel.: +49 (0) 79 31 / 493-14800
In the event of technical malfunctions, contact us at the following address:
WITTENSTEIN cyber motor GmbH
Customer Service
Walter-Wittenstein-Str. 1
D-97999 Igersheim
Tel.: +49 (0) 79 31 / 493-15900
Email: service@wittenstein-cyber-motor.de

Copyright© WITTENSTEIN cyber motor GmbH 2021
This documentation is protected by copyright.
WITTENSTEIN cyber motor GmbH reserves all the rights to photo-mechanical reproduction,
copying, and the distribution by special processes (such as computers, file media, data
networks), even in parts.
Subject to technical and content changes without notice.

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Contents
1

About this manual1
1.1
Signal words2
1.2
Safety symbols
3
1.3
Structure of the safety information
3
1.4
Information symbols
3
2 Product characteristics
4®
2.1
cyber reaction wheel 2
5
2.1.1
2.1.2
2.1.3
2.1.4

Type code
Name plate
Packaging and scope of delivery
System characteristics

3

5
6
6
7

2.1.4.1 DC power, torque and speed
2.1.4.2 Control characteristics

7
8

2.1.5 Electrical data

8

2.2.1
2.2.2
2.2.3
2.2.4
2.2.5

Type code
13
Intended use
13
Packaging and scope of delivery 14
Structure
15
Electrical interfaces
16

2.2.5.1
2.2.5.2
2.2.5.3
2.2.5.4

A: USB port
B: Application interface
D: Interface to reaction wheel
E: Supply voltage

16
17
18
18

2.2.6 LEDs
2.2.7 Application notes

19
19

2.2.7.1 Setting the supply voltage
2.2.7.2 Provision of V-IO for the logic
blocks on the starter kit
2.2.7.3 Integration of digital IOs
2.2.7.4 UART switching
2.2.7.5 Brake chopper: Dissipation ofrecuperation energy

20

2.2.8 Environmental conditions

22

2.3

20
20
21
21

Graphical user interface cyber®
reaction wheel assistant23

2.3.1 Installation of the cyber® reaction
wheel assistant23
2.3.2 CHM-Help
23
2.3.3 Oscilloscope23
2.3.4 Setting of communication
parameters
24

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25

2.3.5.1 Setting the voltage limits
2.3.5.2 Setting speed and current limits

25
26

Startup of the cyber® reaction
wheel 227
3.1
Safety instructions27
3.2
Preparations27
3.3
Startup with the cyber® reaction
wheel assistant27

3.4

2.1.6 Control and setpoint selection of
the reaction wheel
112.1.7 Ensuring availability of thereaction wheel
112.1.8 Environmental conditions
12
2.1.9 Vibration/shock12
2.1.10 Electromagnetic Compatibility
(EMC)
12

cyber® reaction wheel starter kit
13

24

3.3.1 Installation at cyber® reaction
wheel starter kit
3.3.2 Establishing the power supply
3.3.3 Establishing a connection
3.3.4 Speed setting

2.1.5.1 Pin assignment of connector A
92.1.5.2 Pin characteristics of connector A 9
2.1.5.3 Use of digital IOs
10

2.2

2.3.4.1 Setting the I2C address

2.3.5 Changing important systemparameters

28
28
28
29

Prototypical integration of thecyber® reaction wheel 2 into an
ADCS environment
30

3.4.1 Preparations at the cyber® reaction
wheel starter kit
30
3.4.2 Example of an integration of areaction wheel for startup via SPI
with a Nucleo board from ST
30
3.4.3 Communication interfaces
32
3.4.3.1 I2C interface
3.4.3.2 SPI interface
3.4.3.3 UART interface

33
33
34

3.4.4 Wittenstein software stack for
integration of the reaction wheel 35

3.5
3.6

Diagnostics using the cyber®
reaction wheel assistantFirmware update

3536

3.6.1 Firmware update with the cyber®
reaction wheel assistant36
3.6.2 Firmware update with ADCS
36

4

Integration of the cyber® reaction
wheel 2 into a satellite
37
4.1
Electrical integration of thecyber® reaction wheel 2
37
4.2
Mechanical integration of thecyber® reaction wheel 2
38®
4.3
Installation of the cyberreaction wheel 2
38
4.4
Requirements for power
adapters and supply voltage 39
4.5
Installation space39
4.6
Mounting position
39
4.7
Cooling39
4.8
Maintenance39
4.9
Software-side integration in
ADCS
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1 About this manual
These instructions contain information required for the safe use of the cyber® reaction wheel 2
system, also referred to as the reaction wheel and the cyber® reaction wheel starter kit, also
referred to as starter kit.
The document must always be used in connection with the cyber® reaction wheel 2 operating
manual.
Each drive system is clearly described by its serial number (SN).
In case of conflict between this general operating manual and the material-specificdocumentation, the material-specific documentation applies. This project planning guide is valid
for the product (drive system) unless another, material-specific documentation exists.
If this manual is supplied with amendment sheets (e.g. for special applications), then theinformation in the amendment is valid. Contradictory specifications in this manual are therefore
void.
The operator must ensure that this operating manual is read through by all persons assigned to
install, operate, or maintain the drive system, and that they fully comprehend its content.
Store this manual within reach of the drive system.
Inform colleagues who work in the area around the machine about the safety instructions sothat no one sustains injuries.
The original was prepared in German, all other language versions are translations of theoriginal manual.

1.1 Signal words
The following signal words are used to indicate hazards, things that are forbidden andimportant information:

DANGER
This signal word indicates an imminent danger that will cause
serious injuries or even death.

WARNING
This signal word indicates a potential hazard that could cause
serious injuries and even death.

CAUTION
This signal word indicates a potential hazard that could cause
minor or serious injuries.

NOTICE
This signal word indicates a potential hazard that could lead toproperty damage.
A note without a signal word indicates application tips or especially
important information for handling the drive system.

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Project planning guide1.2 Safety symbols
The following safety symbols are used to indicate hazards, things that are forbidden andimportant information:

General danger

Hot surface

Electric voltage

Electrostaticallysensitive device

1.3 Structure of the safety information
Safety information in this manual has been structured according to the following template:

CAUTION
Explanatory text shows the consequences of disregarding thisinformation.
• Instructive text uses direct address to indicate what to do.

1.4 Information symbols
The following information symbols are used:•

Indicates an action to be performedIndicates the results of an action

 Provides additional handling information

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Project planning guide2 Product characteristics
The reaction wheel with integrated servo controller provides a defined angular momentum. It is
used to exchange an adjustable angular momentum with a satellite body. This induced angularmomentum can be used for alignment of the satellite body or for compensation of interferencesfrom the environment. The reaction wheel can be used in satellites with high demands foralignment accuracy.
This document is intended to familiarize the user with the use of the cyber® reaction wheel 2.
Following the product specifications of the cyber® reaction wheel 2, the cyber® reaction wheel
starter kit and the cyber® reaction wheel assistant are the chapter on startup working with thereaction wheel as well as prototypical integration into ADCS including a description of theavailable interfaces SPI, I2C and UART.
In the end, integration into an ADCS is explained.
In addition, the software interface of the cyber® reaction wheel 2 is explained in the interface
control document.
The following table provides an initial overview of the cyber® reaction wheel 2

A
B
C
D
E
F
G

Designation
Power and signal connector
Housing
Base plate
Fastening screw thread
Name plate
Data Matrix code with link to service portal
Serial number

Table 1: Overview of the cyber® reaction wheel 2

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2.1 cyber® reaction wheel 2
The WITTENSTEIN cyber® reaction wheel 2 is an intelligent drive system with a maximum
angular momentum of 2 mNms.
Possible communication interfaces are SPI, I2C and UART.
The intelligence is reflected in an encoderless control system with a high diagnostic depth andthe range of functions of industrial drive technology. The sign change of the angular momentum
as well as the operation throughout the angular momentum range can be done without any
limitations.
Intuitive startup and integration of the drive system is made possible by the cyber® reaction wheel
starter kit with the PC-based, graphical user interface cyber® reaction wheel assistant. It includes
a wide range of options for parameterization, diagnostics and control. The CHM help is also partof the cyber® reaction wheel assistant.
Alternatively, the reaction wheel can be easily started up with a microcontroller using the cyber®
reaction wheel starter kit. For this, WITTENSTEIN cyber® motor offers a communication stackthat ensures easy integration into an ADCS.
Both possibilities for startup are described in sections 3.3 and 3.4.
2.1.1 Type code

Figure 1.1: crw type code

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2.1.2 Name plate
The name plate consists of a laser inscription on the motor housing.
Designation
1
Product designation
2
Calendar week and year of production
3
DC bus voltage UDC
4
Maximum power Pmax, el
5No-load speed n0
6
DC bus current IDC
7
Angular momentum Ln
8
Mass m9
Maximum torque Mmax
10
Protection class11
Manufacturer
12
Data Matrix code: Serial number
Table 2: Name plate of cyber® reaction wheel 2

Customized deviations are permissible.
The Data Matrix code (DMC) under the name plate is in the format C18x18 according to ECC200.
It contains the Service Portal Address including the Service Portal Code.

2.1.3 Packaging and scope of delivery
The drive system is delivered packed in foil and/or cardboard boxes.
• Dispose of the packaging materials at the recycling sites intended for this purpose.
Please observe the valid national regulations for waste disposal.
•

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Check the completeness of the delivery against the delivery note.
 Immediately notify the carrier, the insurance company, or
WITTENSTEIN cyber motor GmbH in writing of any missing parts or damage.

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2.1.4 System characteristics
The maximum admissible technical data is described in the following table 3
For additional information, please contact our sales department. Always state the serial number(SN) when doing so.
System data

Unit

Value

Angular momentum at 18000 rpm

mNms

2

Max. speed

rpm

19000

Nominal speed

rpm

18000

Nominal power1

W

0.2

Max. acceleration time to 18000 rpms

7Max. acceleration

rev/s²

60

Max. deceleration with recuperation

rev/s²

60

Max. deceleration without recuperation

rev/s²30

Weightg

30

Max. static imbalance

gmm

0.02

Max. dynamic imbalance

gmm²

0.2

Table 3: System characteristics of cyber® reaction wheel 2

2.1.4.1 DC power, torque and speed
The following figure shows the DC power and torque against the speed at different accelerations.

Figure 1.2: DC power and torque profiles against the velocity at accelerations of the cyber® reaction wheel 2 from 0 rev/s² to
60 rev/s² at UDC = 5 V
1

The rated connection power refers to operation at a stationary velocity of 8000 rpm with run-in bearings and an intermediate
circuit voltage of 5 V. After an extended standstill, power consumption may be temporarily increased.
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2.1.4.2 Control characteristics
According to the following figure, the cyber® reaction wheel 2 can be approximated as a first or
second order system.

Figure 1.3: Illustration of the step response of the cyber® reaction wheel 2 at an acceleration jump from 0 rev/s² to 60 rev/s²

Wittenstein recommends using a transfer function second order with the following parameters for
simulation to better map the settling time:
1+Tz*sG(s) = Kp * -------------------------------- * exp(-Td*s)
1+2*Zeta*Tw*s+(Tw*s)^2
Kp = 0.983
Tw = 0.228
Zeta = 1.867
Td = 0.01
Tz = 0.908
SettlingTime: ~1.7
Overshoot: ~10 %2.1.5 Electrical data
Electrical data

Unit

Value

Nominal supply voltage

V DC

5

Supply voltage range

V DC

3.0…8.8

Max. power input (configurable)

mW

<2000

Inrush current power off/on

mA

480

Inrush current disable/enable

mA

560

Plug-in cycles for connector A

numbermax. 30®

Table 4: Overview of electrical data of the cyber reaction wheel 2

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2.1.5.1 Pin assignment of connector A
FigurePin no.

Signal name

Function

17
18
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
19
20

GND
GND
Chopper_Ena
I2C_SCL
IO_1
I2C_SDACAN_RxSPI_MOSICAN_TxSPI_MISO
UART_Tx
SPI_nCS
UART_Rx
SPI_CLK
USB_M
USB_P
IO_2
IO_3
VDD
VDD

Ground reference
Ground reference
Output signal, underclocking
I2C bus SCL
User Output 1
I2C bus SDA
Reserved for CAN Rx
SPI Bus MOSI
Reserved for CAN Tx
SPI Bus MISOUART Tx
SPI Bus Chip-Select
UART Rx
SPI Bus ClockReserved for USB DReserved for USB D+
User Output 2
User Input 1
Supply voltage
Supply voltage

Connector type for connection of cyber® reaction wheel 2: MOLEX SlimStack
PCB connector (16+2) 505070-1622
For alignment of the connector on the drive system, see dimensional drawing,
document number 5007-D060499.
Table 5: Pin assignment of connector A at the cyber® reaction wheel 2

2.1.5.2 Pin characteristics of connector A
Direction

Size

Value

Affected pins

General limits

Input

Maximum voltage forlow level
Minimum voltage forhigh level
Maximum voltage at
low level
Minimum voltage athigh level

1.2 V

2, 4, 5, 6, 10, 11, 12,
13, 14

Permitted voltage range
of inputs: 0 V - 3.6 V

1, 3, 4, 7, 8, 9, 15

Permitted maximum
current of outputs:±4 mA each

Output

1.9 V
0.4 V
2.4 V

Table 6: Pin characteristics of connector A at the cyber® reaction wheel 2

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2.1.5.3 Use of digital IOs
The digital IOs user output 1, user output 2 and user input 1 specified in the tables 5 and 6 canbe functionally configured by the user. The configuration options are documented in the CHM
help in the cyber® reaction wheel assistant.
To do so, simply tap digital IO help and configure the digital IOs within the digital IO tile (1).

(1)

Figure 1.4: Display and application of the configuration optionsof the digital IOs for the cyber® reaction wheel 2

For information on how the digital IOs can best be integrated into the application, please refer tosection 2.2.7.3.
The configuration example below describes use of the reaction wheel with the cyber® reaction
wheel starter kit:
As described in table 17,- User output 1 is wired to a red LED- User output 2 is wired to a green LED
on the cyber® reaction wheel starter kit.
In this configuration example, the red LED lights up in case of a fault in the drive and the green
LED as soon as the setpoint velocity is reached:

Figure 1.5: Configuration example of user output 1 and 2 for the cyber® reaction wheel 2 for displaying an error with the red
LED and displaying the velocity status with the green LED during operation with the cyber® reaction wheel starter kit

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2.1.6 Control and setpoint selection of the reaction wheel
The software of the reaction wheel offers numerous options for control and diagnostics.
For this purpose, the reaction wheel is operated in velocity control mode.
For specification of the angular momentum, acceleration, deceleration and a velocity setpoint are
specified. The velocity setpoint is then approached with the set gradients. Changing the velocityof the rotating inertia causes an angular momentum of the required value and in the required
direction.
A positive value of the velocity results in revolution of the rotor in counterclockwise direction whenviewing the housing from above (see table 1). Respectively, entering of a positive acceleration
results in a clockwise reaction torque to the application.
The change velocity (acceleration/deceleration) of the angular momentum as well as the velocity
setpoint can be set as required within the limits defined in table 3.
Chapters 3 and 4 describe in detail the options for initial startup and integration of thereaction wheel:• Initial startup with the cyber® reaction wheel assistant (see section 2.3) and the cyber®
reaction wheel starter kit (see section 2.2) within a few minutes: Section 3.3• Startup with the cyber® reaction wheel starter kit and a microcontroller for prototypicalintegration into an ADCS: Section 3.4.
• Integration of the cyber® reaction wheel 2 into an ADCS: Chapter 4
Installation of the cyber® reaction wheel assistant (see section 2.3) provides automatic access to
the CHM help in addition to the options for easy startup and diagnostics.

2.1.7 Ensuring availability of the reaction wheel
The reaction wheel has implemented numerous mechanisms to maximize availability.
These include:- Temperature, current and voltage monitoring- Monitoring of internal voltage references and power supply units- Monitoring of FLASH and RAM memory as well as correction of corrupt addresses- Fault memory for detailed diagnostics, see CHM help of the cyber® reaction wheel assistant

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Wittenstein strongly recommends maintaining the voltage supply to the reaction wheels at all
times. This is the only way to ensure that the monitoring and repair mechanisms mentioned
above are functional and that the availability of the reaction wheel is maximized.
Energy consumption is therefore reduced to a minimum during no-load operation of thereaction wheels.

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2.1.8 Environmental conditions
The cyber® reaction wheel 2 can be stored on the ground for 2 years before use.
Environmental conditions

Unit

Value

Operating ambient temperature range°C-40 … 852

Survival ambient temperature range°C-40 … 100

Nominal ambient temperature range3°C

0 … 55Max. radiation dose

Gy

200

Minimum ambient pressure

mbar

10-8

Table 7: permitted ambient conditions

2.1.9 Vibration/shock
The drive system fulfills the following specifications:•••Vibration according to DIN EN 60068-2-6:2008
Frequency range 5 Hz – 2000 Hz
Acceleration: 1 g – 8 g
Broadband noise according to DIN EN 60068-2-64:2008
Frequency range 20 Hz – 2000 Hz
Acceleration RMS: 7.5 g
Shock according to DIN EN 60068-2-27:2009
Shock form: semi-sinusoidal
Acceleration: 40 g
Shock duration: 3 ms

2.1.10 Electromagnetic Compatibility (EMC)
The system meets the requirements for interference immunity according to EN 61000-4-3(electromagnetic HF field) and EN 61000-4-4 (fast transients) as well as interference emissions
according to EN 55011 (interference voltage at the power supply connection and radiatedinterference emission).

2

At 85 °C, a permanent acceleration and deceleration of 10 rev/s² is possible for the speed range from -1500 rpm to 1500 rpm.
Between 1500 rpm and 10000 rpm, a permanent acceleration and deceleration of 60 rev/s² is possible.
3
In this temperature range, the crw can be operated continuously over the complete speed range with the maximum
acceleration of 60 rev/s² if the thermal connection is sufficient.
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2.2 cyber® reaction wheel starter kit
The WITTENSTEIN cyber® reaction wheel starter kit is a startup platform for the cyber®
reaction wheel 2. This platform makes it very easy to start up the reaction wheel via USB and thecyber® reaction wheel assistant. The voltage can be supplied via USB port or alternatively via an
external power supply unit.
For connection of the cyber® reaction wheel 2 to a microcontroller (e.g. an ADCS), all signals atconnector B are routed to the outside (see table 9).
This chapter describes the detailed structure of the starter kit and its intended use. Chapter 3
describes the various options for startup and integration of the cyber® reaction wheel 2 with thecyber® reaction wheel starter kit.
Section 2.2.7 presents application examples for implementation and verification with thestarter kit.
2.2.1 Type code

Figure 1.6: crws type code

2.2.2 Intended use
The cyber® reaction wheel starter kit is intended exclusively for startup of the cyber® reaction
wheel 2. Integration of the cyber® reaction wheel starter kit into any commercially available
products is not permitted.

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cyber® reaction wheel 2

Project planning guide2.2.3 Packaging and scope of delivery

On delivery, the cyber® reaction wheel starter kit is packaged in foil and/or cardboard.
• Dispose of the packaging materials at the recycling sites intended for this purpose.
Please observe the valid national regulations for waste disposal.
• Check the completeness of the delivery against the delivery note.
 Immediately notify the carrier, the insurance company, or
WITTENSTEIN cyber motor GmbH in writing of any missing parts or damage.
cyber® reaction wheel starter kit
1 PCB for startup
1 USB cable2 screws, DIN 912 M2x4, for mounting the cyber® reaction wheel 2

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Project planning guide2.2.4 Structure
Table 8 and figure 1.7 provide an overview of the starter kit and its interfaces.
DesignationA
USB port
B
Application interface
C
Only for manufacturer
DInterface to reaction wheel
E
Supply voltage
F
Slot for reaction wheel
G
Fixing bores for starter kit
H
Screws DIN 912 M2x4
I
Reaction wheel (not included in the scopeof delivery of the cyber® reaction wheel
starter kit)

Table 8: Overview of external interfaces of the starter kit

C

B

G

G

F
E
D

1

F

A

G

G

Figure 1.7: Illustration of the external interfaces of the cyber® reaction wheel starter kit

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Project planning guide2.2.5 Electrical interfaces

The following section describes the electrical interfaces as shown in figure 1.7 at the starter kit aswell as their properties.
Connector

Function

Plug connector type
crws

Plug connector type
remote endA

USB port

Mini-USB B socket

Mini USB connector

B

Application interface

C

Programming
interface
Interface to reaction
wheel

Pin connector, 20-pin,male, grid 2.54 mm
Only for manufacturer

Socket strip, 20-pin, female,
grid 2.54 mm
Only for manufacturer

MOLEX SlimStack PCB
connector (16+2)
5050701622
2-pin screw terminal

MOLEX SlimStack PCB
connector (16+2)
5050661622
Open cable

DE

Supply voltage

Table 9: Overview of starter kit plug connectors

2.2.5.1 A: USB port
The USB port is used for easy startup,for communication with the cyber® reaction wheel assistant, see section 3.3,
as well as for voltage supply (if necessary, derating the reaction wheel due to available
power of the USB voltage source)
and for diagnosis of the reaction wheel during integration, see section 3.5
The USB interface is based on a FT232R USB-to-serial UART interface from FTDI.
In the customer application, the pins UART Rx/Tx can be controlled directly, see section 2.2.7.4.
Connection

Property

Unit

USB 2.0

Voltage supply and/or
communicationinterface for startup
tool

V

Minimum
value

Nominalvalue
5.0

Maximum
value

Table 10: Electrical properties of application interface, connector B, at the cyber® reaction wheel starter kit

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Project planning guide2.2.5.2 B: Application interface
Application interface B, see figure 1.7, is intended for fast and prototypical integration of thereaction wheel into the target application. Section 3.4 describes how this is to be done.
All signals listed below have an ESD protection diode.
FigureB

Pin no.

Signal name

Function

1
2
3

GND
GND
Chopper_Ena

4
5
6
7

I2C_SCL
IO_1
I2C_SDA
Reserved

8
9

SPI_MOSI
Reserved

10
11
12
13
14
15

SPI_MISO
UART_Tx
SPI_nCS
UART_Rx
SPI_CLK
Reserved

16

Reserved

17
18
19
20

IO_2
IO_3
V-IO
VDD

Ground reference
Ground reference
Activation ofunderclocking (Out)I²C Bus SCL (In)
User Ouput 1
I²C Bus SDA (Bi)Reserved for CAN Rx(In)
SPI Bus MOSI (In)Reserved for CAN Tx(Out)
SPI Bus MISO (Out)Serial interface (Out)SPI Bus Chip-Select (In)
Serial interface (In)SPI Bus Clock (In)Reserved for USB D(Bi)Reserved for USB D+(Bi)User Ouput 2
User Input 1
Logic supply
Reaction wheel supply

Table 11: Pin assignment of application interface, connector B, at the cyber® reaction wheel starter kit

Connection

Property

Unit

V-IO
VDD
Chop_Ena
I2C_xx
User_IO_x
CAN_xx
SPI_xxx
UART_xx
USB

Voltage
Voltage
Voltage
Voltage
Voltage
Voltage
Voltage
Voltage
Voltage

V
V
V
V
V
V
V
V
V

Minimum
value
3.0
3.0

3.0

Nominalvalue
3.3 / 5.0
5.0
Corr. to V-IO
Corr. to V-IO
3.3
Corr. to V-IO
Corr. to V-IO
Corr. to V-IO
typ. USB

Maximum value
5.5
8.8

3.6

Table 12: Electrical properties of application interface, connector B, at the cyber® reaction wheel starter kit

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Project planning guide2.2.5.3 D: Interface to reaction wheel
FigurePin no.

Signal name

17
18
1

GND
GND
Chopper_Ena

Function

Ground reference
Ground reference
Activation ofunderclocking
2
I2C_SCLI²C Bus SCL3
IO_1
User Ouput 1:
red LED on starter kit
4
I2C_SDAI²C Bus SDA
5
Reserved
Reserved for CAN Rx
6
SPI_MOSISPI Bus MOSI
7
Reserved
Reserved for CAN Tx
8
SPI_MISOSPI Bus MISO
9
UART_Tx
Serial interface10
SPI_nCS
SPI Bus Chip-Select11
UART_Rx
Serial interface
12
SPI_CLKSPI Bus Clock13
Reserved
Reserved for USB D14
Reserved
Reserved for USB D+
15
IO_2
User Ouput 2:
green LED on starter kit
16
IO_3
User Input 1
19
VDD
Reaction wheel supply
20
VDD
Reaction wheel supply
Connector type at starter kit: MOLEX SlimStack PCB connector (16+2)
5050701622
Table 13: Pin assignment of interface to reaction wheel, connector D, at the cyber® reaction wheel starter kit•

Observe the maximum number of 30 plug-in cycles for the interface to the reaction wheel.
Connection

Property

Unit

Signals 1-16
VDD

Voltage
Voltage[V][V]

Minimum
value
3.0
3.0

Nominalvalue
3.3

Maximum value
3.6
8.8

Table 14: Electrical properties of application interface, connector D, at the cyber® reaction wheel starter kit

2.2.5.4 E: Supply voltage
Besides voltage supply via USB port (A), see section 2.2.5.1, a power supply unit can also be
used directly. This is recommended if the reaction wheel is operated very dynamically, as thepower supplied from the USB port is not sufficient for stable supply of the reaction wheel at every
operating point.
FigurePin no.

SignalFunction

1
2

VDD
GND

SupplyGround reference

Connector type at starter kit: 2-pin screw terminal
Table 15: Pin assignment of supply voltage, connector E, at the cyber® reaction wheel starter kit

Connection

Property

Unit

VDD

Voltage[V]

Minimum
value
3.0

Nominalvalue
5.0

Maximum
value
8.8

Table 16: Electrical properties of supply voltage, connector E, at the cyber® reaction wheel starter kit

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Project planning guide2.2.6 LEDs
The starter kit has a total of 6 LEDs, the functions of which are described in the following table:
Ref

Color

SignalNotice

D4
D8
D9
D13
D22

green
red
green
red
red

Supply voltage
USB Rx/Tx
USB Rx/Tx
Chopper active
User_IO_1

D23

green

User_IO_2

Power label on starter kit;
TxD label on starter kit;
RxD label on starter kit;
Chopper label on starter kit;
User_IO_1 label on starter kit;
Output controls the red LED, see section 2.1.5.3
User_IO_2 label on starter kit;
Output controls the green LED,see section 2.1.5.3

Table 17: function of the LEDs at the cyber® reaction wheel starter kit

2.2.7 Application notes
This section on the starter kit deals with the implemented circuit modules, which are illustrated infigure 1.8. In the following, application examples are derived and explained based on thesecircuit modules.

Application interface B

UART
Switching

E: Supply
Voltage
Interior: Brake
chopper
A: USB

center:J7 / R23

bottom:LEDs

Figure 1.8: Illustration of function blocks on the cyber® reaction wheel starter kit

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Project planning guide2.2.7.1 Setting the supply voltage
Option 1:
Connect USB port A to a remote end using the provided USB cable.

Option 2:
With the USB cable not connected, a supply voltage can be set within the specified limits via
screw terminal E.
To be able to supply a supply voltage lower than the USB voltage via screw terminal E while theUSB cable is connected, the 0 Ω resistor, R54, must be removed as illustrated in figure 1.8,
block E. In case of frequent changes, a jumper can be refitted for J10.

2.2.7.2 Provision of V-IO for the logic blocks on the starter kit
Except for the signals IO_1 (pin 5, connector B), IO_2 (pin 17, connector B) and IO_3 (pin 18,
connector B), as well as the reserved pins 15 and 16 on connector B, all signals refer to V-IO,
pin 19, connector B. The assignment of connector B is described in section 2.2.5.2.
This voltage must be supplied externally at pin 19 at the external plug connector B. Alternatively,
a connection to the internal 3.3 or 5 V must be established with a 0 Ω resistor:

0R0 = fit toconnect V-IO to
3.3 or 5 V
Figure 1.9: Illustration of the circuit diagram section for supplying the logic
blocks on the cyber® reaction wheel starter kit

Notice: The internally generated 3.3 V and 5 V are not intended for supplying external consumers
via pin V-IO_ext.
2.2.7.3 Integration of digital IOs
The digital IOs are decoupled via a series resistance of 100 Ω. The 3.3 V level must always becomplied with:

Figure 1.10: Illustration of the circuit diagram section for the user IOs on
the cyber® reaction wheel starter kit

The two signals IO_1 and IO_2, see section 2.2.5.3, additionally have a red and/or green LED
against GND (high-active) to indicate the status of the reaction wheel. The configuration options
for these two outputs are described in section 2.1.5.3.

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Project planning guide2.2.7.4 UART switching
The reaction wheel provides a UART interface as described in section 3.4.3.3. It can be patchedon the starter kit by means of S1 UART switch either to the USB-UART converter for startup withthe cyber® reaction wheel assistant as described in section 3.3 or alternatively on the applicationinterface for integration into the target application as described in chapter 4 or section 3.4 byswitching to position UART uC.
When it comes to integration into the target environment according to chapter 4, the two Rx/Tx
signals can be controlled directly with 3.3 V. A serial protection and termination resistor in therange of 1 kΩ ... 3.3 kΩ is recommended as close to the signal source as possible:
SignalLevel

Signal source

Signal target

Series resistance

UART_Tx
UART_Rx

3.3 V
3.3 V

Reaction wheel
Customer

Customer
Reaction wheel

Near reaction wheel
Near customer

Table 18: UART switching

2.2.7.5 Brake chopper: Dissipation of recuperation energy
The reaction wheel was designed for dynamic deceleration and acceleration processes. In caseof decelerations as of 30 rev/s², see table 3, the feedback energy may exceed the energy
consumption of the reaction wheel.
If no other "consumer" is connected or the energy can be fed back, the supply voltage increases.
This behavior can be easily adjusted, for example, if the reaction wheel is supplied via USB anddecelerated at max. deceleration. In this case, the supply voltage increases, exceeding thedefault limit of 7 V. The reaction wheel switches down to the limit and indicates this as an error.
For this reason, the circuit on the starter kit is designed and implemented as illustrated infigure 1.11.

Figure 1.11: Illustration of the circuit diagram section for implementing a brake chopper for dissipation of recuperation energy

This circuit module interacts with pin 1, Chopper_Ena, of the reaction wheel according totable 5 and can be configured in the cyber® reaction wheel assistant in the power screen,
see figure 1.13.

Figure 1.12: Configuration of the pin for
dissipation of recuperation energy during
braking

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Project planning guideTo activate the circuit module, the chopper control field must be set to "On". Afterwards, carry out
the voltage settings required for the application. Do you want to save the setting permanently?
In this case, click the button Save to EEPROM to maintain the settings even after a power failure.
The settings presented above causes switch T2 to be switched on by the Chopper_Enable signal
from the reaction wheel when the voltage threshold of 6.5 V is exceeded and be switched off
when the voltage falls below that threshold.
As soon as T2 is switched on, the energy feedback is converted into heat via resistors R27, R28,
R35 and R36.
For the target application, we recommend adopting the circuit module as long as no consumers
are connected to the supply system of the reaction wheels that can absorb the energy feedback.
•Notice: The pin Chopper_Ena is activated in the example as of 6.5 V. For this reason, it must
be ensured that the supply voltage is always below the set threshold voltage while thismodule is being used. Otherwise, the module or T2 is permanently activated,which generates power loss and heating.

2.2.8 Environmental conditions
Environmental conditions
Operating ambient temperature range
Operating air humidity

Unit

Value

°C

0 … 40%< 95, non-condensing®

Table 19: Ambient conditions of the cyber reaction wheel starter kit

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2.3 Graphical user interface cyber® reaction wheel assistant
The graphical user interface cyber® reaction wheel assistant allows a very fast, easy andcomprehensive startup and diagnosis of the reaction wheel. The assistant uses UART toestablish a connection to the reaction wheel and allows startup as stand-alone module as
described in section 3.3. Furthermore, the cyber® reaction wheel assistant can be used very wellfor diagnostics when integrating the reaction wheels into the target application. The options forthis are explained in section 3.5.
With the cyber® reaction wheel assistant, the user can also set the I2C address and the baud rateof the reaction wheels for the target application, for example. Information and assistance can befound in the CHM-Help of the cyber® reaction wheel assistant.
2.3.1 Installation of the cyber® reaction wheel assistant
The cyber® reaction wheel assistant is required to be able to easily control the reaction wheel.
System requirements:

Figure 1.13: System requirements for installation of the cyber® reaction wheel assistant

2.3.2 CHM-Help
CHM-Help is an integral part of the cyber® reaction wheel assistant. This integrated help tool
provides information on all parameters and screens and detailed descriptions.
The CHM-Help can be accessed best by pressing F1 when the cyber® reaction wheel assistant isopen. More targeted help is provided by clicking on the question markin the respective
context menu.
2.3.3 Oscilloscope
The oscilloscope is a very helpful diagnostics tool for the reaction wheel. The feature is locateddirectly in the main menu of the cyber® reaction wheel assistant by clicking the Scope menu item.
With its eight freely configurable channels, many states can be recorded, analyzed, exported andimported.
The scope of functions of the oscilloscope is also described in the CHM-Help. To access it,
simply click onin the Scope menu.

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2.3.4 Setting of communication parameters

2.3.4.1 Setting the I2C address
1) Open the CHM-Help2) Search index 3E06
3) Set the required address according to the parameter description in CHM-Help or the
figure below

Figure 1.14: Example of the 0x3E06 parameter for setting the I2C address in the CHM-Help of the cyber® reaction
wheel assistant4) Save to EEPROM: This saves the address permanently in the reaction wheel.
5) Restart Drive: The reaction wheel starts with the new address.

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2.3.5 Changing important system parameters
2.3.5.1 Setting the voltage limits
The necessary parameters are listed in the Power screen of the cyber® reaction wheel assistant.
The CHM-Help for the parameter can be accessed by clicking on the corresponding field andpressing F1 or clicking the question mark circled in blue.

Figure 1.15: Screen for setting the voltage limits

Click on Save to EEPROM in the upper menu ribbon to permanently save the changes in thereaction wheel. Otherwise, the previously set values will be loaded again after the next restart.
Index

Description

upper limit

lower limit

Default

Access0x3A05Nominal voltage

5V

5V

5V

ro

0x3A06Lower hardware
voltage limit
Upper hardware
voltage limit
Lower user
voltage limit
Upper user
voltage limit
Brake chopper
threshold voltage

2.7 V

2.7 V

2.7 V

ro

9.3 V

9.3 V

9.4 V

ro

0x3A07

0x3A06

2.8 V

r/w

0x3A07

0x3A06

7.0 V

r/w

0x3A07

0x3A066.5 V

r/w

0x3A07
0x3A1C
0x3A1D
0x3A19

Table 20: Parameters for setting the voltage limits

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2.3.5.2 Setting speed and current limits
The necessary parameters are listed in the Limits and Power screen of the cyber® reaction wheel
assistant. The CHM-Help for the parameter can be accessed by clicking on the corresponding
field and pressing F1 or clicking the question mark circled in blue.

Figure 1.16: Screen for setting system limits, e.g., current limits

Index

Description

upper limit

lower limit

Default

Access0x3A0B

Max. DC current

0.9 A

0.9 A

0.9 A

ro

0x6073

Maximum motor
current
Maximum powerelectronics current
Maximum user phasecurrent
Used current limit

0.46 A

0.46 A

0.46 Aro0.46 A

0.46 A

0.46 Aro0.46 A

0A

0.46 Ar/w--

Min(0x60 ro
73,0x3A04,0x3A45)

0x3A04
0x3A450x3610

Table 21: Parameters for setting the system limits

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Project planning guide3 Startup of the cyber® reaction wheel 2
3.1 Safety instructions•••

For mechanical installation, the ESD information must be observed.
The drive system must be checked for mechanical damage before installation. Only installreaction wheels that are in perfect working condition.
Operation of reaction wheels with condensation on them is not permitted.

CAUTION••

The drive system may only be assembled with the power
disconnected.
Installation may only be performed by trained personnel.

3.2 Preparations

NOTICE
Compressed air can damage the drive system.
•
Do not use compressed air to clean the drive system.

NOTICEThe system can be damaged by electrostatic discharge.
• Observe the directives concerning ESD protection.

NOTICE
Dirt particles may cause damage to the system.
• Ensure cleanliness.

NOTICE
Incorrect handling may result in damage to the system.
• Proceed with utmost caution.
••••

In addition, check the fitting surfaces for damage and impurities.
For drive systems, use screws of property class A2-70 or titanium grade 5.
Do not use any washers.
Installation of the cyber® reaction wheel assistant (see section 2.3.1)

3.3 Startup with the cyber® reaction wheel assistant
The following section describes startup of the reaction wheel with the cyber® reaction wheel
starter kit and the cyber® reaction wheel assistant.

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Project planning guide3.3.1 Installation at cyber® reaction wheel starter kit
To do this, perform the following steps:

Secure the reaction wheel (I) in the required axis configuration to the starter kit (G) using
screws (H).
•••

If the cyber® reaction wheel is to be
detached from the starter kit again, do
not use threadlocker.
Fasten the reaction wheel to thestarter kit using the fastening
screws H.
Make sure the unused second
connector (red marking) is protectedagainst contact with conductive
components.

Fastening screws
MA = 0.11 Nm

3.3.2 Establishing the power supply
1. Connect the USB cable included with the starter kit to the PC on which the cyber® reaction
wheel assistant has been installed and to the USB port A (see section 2.2.5.1) on the starterkit. The reaction wheel is then already supplied with voltage via the USB port.
2. Set the UART uC / USB PC switch at the starter kit to USB PC
3. There is also the option of connecting an external supply voltage to screw terminals E in
addition to the USB voltage as described in section 2.2.5.4. This allows operation under all
load conditions. Observe the maximum permitted input voltage according to section 2.1.5.
3.3.3 Establishing a connection
1. Open the cyber® reaction wheel assistant with a double-click
2. Select Device ReactionWheel[…]
3. Press "Connect" to establish a connection

3

2

Figure 1.17: Establishing a connection to the cyber® reaction wheel 2

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3.3.4 Speed setting
1. Open Service motion

1

Figure 1.18: Open the screen for specifying the velocity in the cyber® reaction wheel assistant

2. Select "Continuous" mode
3. Enter the velocity specification under "Target velocity 1" with the desired acceleration in the"Acceleration" field and deceleration in the "Deceleration" field.
4. Confirm the entry by pressing "Disabled" or F5 (button changes to green and Enabled)
5. Start the rotation of the rotor with "PLAY"
6. The status variables of the reaction wheel can be viewed and/or recorded in the Monitor 6a or
Scope 6b screen.
4

2
6b
6a

3

5
Figure 1.19: specifying the velocity in the cyber® reaction wheel assistant

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3.4 Prototypical integration of the cyber® reaction wheel 2 into an ADCS environment
For control and diagnosis of the reaction wheel with a microcontroller, e.g. an ADCS, theinterfaces I2C, SPI and UART as well as a Wittenstein communication stack are provided asa C code. All relevant functions for control and diagnostics of the reaction wheel are
implemented in the stack provided. A documentation can be found in the download portal of thecyber® reaction wheel 2 in the Interface Control Document (https://cybermotor.wittenstein.de/de-de/download-reactionwheel/).
Basic control of the drive system with a microcontroller platform is explained below.
3.4.1 Preparations at the cyber® reaction wheel starter kit
Communication with the cyber® reaction wheel 2 via the cyber® reaction wheel starter kit isrealized via application interface B with pin assignment according to table 11 in section
2.2.5.22.2. Depending on the required communication interface, the corresponding pins must beconnected to the pins of a suitable microcontroller.
In addition, the logic voltage (3.3 V or 5 V) must either be supplied externally at pin 19,
connector B or a connection must be established to the internal 3.3 V or 5 V via a 0 Ω resistor(see section 2.2.7.2).

3.4.2 Example of an integration of a reaction wheel for startup via SPI with a Nucleo board
from STµC PCB, e.g. Eval Board
for ADCS

ADCS
softwareWittenstein
Stack

V-IO
V-IO

SPI_nCS
SPI_MISO
SPI_MOSISPI_CLK

GND

Figure 1.20: Schematic integration of the starter kit with reaction wheel for initial startup using SPI

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Depending on the interface used, the following connections must be established between the
Nucleo Board and one or more starter kits:
NucleoBoard(general)CN
7

10Communication master(specific)

Pin
18

19
28
30
32
3
5
9
18
20
21
25
26
28
33
34
35
37

Axis
-

X
Y
Z
All
All
Z
X
All
All
All
X
Z
Y
Y

Interface
-

SPI
SPI
SPI
I2C
I2C
UART
UART
SPI
SPI
SPI
UART
UART
UART
UART

reaction wheel
starter kit J2(all axes)

Name
5V

GND
SPI_nCS_X
SPI_nCS_Y
SPI_nCS_Z
I2C_SCL
I2C_SDAGND
UART_RX_Z
GND
UART_TX_X
SPI_CLKSPI_MOSISPI_MISO
UART_RX_X
UART_TX_Z
UART_TX_Y
UART_RX_Y

Pin
20

Name
VDD

19

V IO

1, 2
12
12
12
4
6
1, 2
11
1, 2
13
14
8
10
11
13
13
11

GND
SPI_nCS
SPI_nCS
SPI_nCSI2C_SCL
I2C_SDAGND
UART_TXGND
UART_RXSPI_CLKSPI_MOSISPI_MISO
UART_TX
UART_RX
UART_RX
UART_TX

Comment

Supply (optional),
alternatively via
USB or screw
terminal
Supply IO(optional),
see 3.4.1
Reference

Reference
RX/TX crossing
Reference
RX/TX crossing

RX/TX crossing
RX/TX crossing
RX/TX crossing
RX/TX crossing

Table 22: Specification of pin assignment during a prototypical startup of the reaction wheel with an
STM32 Nucleo Board

Further information on the required integration of the Wittenstein stack is described in
section 3.4.4.

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3.4.3 Communication interfaces
The cyber® reaction wheel 2 offers the following communication interfaces as an interface toa higher-level system:
I2C
SPI
UART
All three interfaces can be used in parallel. A precondition for this is that the interface is switched
after the last command has been completed. The reaction wheel always switches to the interface
which has at last received a signal.
Redundant provision of several interfaces can make sense to increase the availability of thecyber® reaction wheel 2. With a simple structure, several reaction wheels can be integrated inparallel by using all available communication interfaces as schematically illustrated in figure 1.21.
The special features of the interface are explained in the sections 3.4.3.1 - 3.4.3.3. Integration of
the Wittenstein communication stack is described in section 3.4.4.
I2C and SPI can be used to transmit the setpoint values for velocity, acceleration anddeceleration either synchronously or asynchronously to the reaction wheels. For the normallyprioritized synchronous setpoint transmission, the reaction wheel uses the broadcast message ataddress 0x0 at the I2C bus.
• When this combination is used, it must be ensured that this message does not interfere withother I2C participants or that they do not interfere with it.

µC PCB, e.g. Eval Board
for ADCS

ADCS
softwareWittenstein
Stack

SPI
I2C
UART

Figure 1.21: Schematic integration of several starter kits with reaction wheels for startup of all interfaces with multiple axes

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3.4.3.1 I2C interface
The I2C bus is a master/slave bus system. The controlling microcontroller acts as the master, thedifferent cyber® reaction wheels 2 as slaves.
The I2C interface is based on two lines. The clock line (SCL) and the data line (SDA) of themaster are connected with all cyber® reaction wheel 2 to I2C_SCL or I2C_SDA of customer
interface B (see table 11) of the starter kit or the interface for reaction wheel D, see table 13.
I2C clock frequency:
The I2C master can be used in standard mode (= 100 kHz) and in fast mode (= 400 kHz).
I2C addressing:
The cyber® reaction wheel 2 uses 7 bits for addressing. The default address is 0x77 (119 dec).
This must be changed by the user during startup with the help of the cyber® reaction wheel
assistant as described in section 2.3.4.1 so that, for example, after a firmware update(see section 3.6), no address is used twice in the network. The address can also be changed with
the Wittenstein software stack with ADCS without any problems. For synchronous setpointtransmission, please observe the information in the introduction of this chapter.
3.4.3.2 SPI interface
The SPI bus is a master/slave bus system. The controlling microcontroller acts as the master, thedifferent cyber® reaction wheels 2 as slaves.
The SPI interface is based on four lines. The two data lines (MOSI, MISO) and the clock line
(SCK) are star-wired to the various reaction wheels 2 to SPI_MOSI, SPI_MISO and SPI_SCK atcustomer interface B, table 11, of the starter kit or the interface to reaction wheel D, table 13.
The chip select line (nCS) is used for data transmission by the microcontroller of the selectedcyber® reaction wheel 2. This is why each cyber® reaction wheel 2 has its own chip select line.
This line is connected to SPI_nCS of the customer interface B, table 11, the starter kit or theinterface to reaction wheel D, table 13.
SPI clock frequency:
The SPI should use a clock frequency of at least 1 MHz. The maximum permitted clock frequency
is 10 MHz.
SPI settings, see figure 1.22:
Mode:Full-Duplex Master
Frame format:
Motorola
Data size:
8 bitsFirst bit:
MSB (=highest bit) first
Clock Polarity (CPOL): 0
Clock Phase (CPHA):
0

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Figure 1.22: Illustration of SPI settings for CPHA and CPOL in the reaction wheel

3.4.3.3 UART interface
The UART bus is not a master/slave bus system but consists of equal stations.
The UART interface consists of two lines. The transmission line (Tx) of the controlling
microcontroller is connected to UART_RX and UART_TX at customer interface B, table 11, of thestarter kit or the interface to reaction wheel D, table 13.
Remember to set the "UART switching" selection switch, see figure 1.8, to UART uC.
As UART is a point-to-point connection, a separate UART channel must be provided for eachcyber® reaction wheel 2. Alternatively, a multiplexer switched by the microcontroller can be used.
UART settings:
Baud rate in Bits/s:
Data size:
Parity:Stop bits:

adjustable: 9600, 19200, 38400, 57600, 115200 (default)
8 bitsno1

The default baud rate of 115200 bits/s is set on delivery and after a firmware update. Parameter0x3E07 Communication UART Baud Rate can be used to change the baud rate. For a detailed
description of the baud rate setting, refer to parameter 0x3E07 in the CHM help.
The cyber® reaction wheel assistant offers a good starting point in the menu item
.

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3.4.4 Wittenstein software stack for integration of the reaction wheel
The example project provided in the download portal of the cyber® reaction wheel 2 for thecontrolling microcontroller consists of the following layers:

Application
exampleCommunicationinterfaces

The communication interfaces are already described in section 3.4.3.
The example project itself is divided into different layers.
To successfully adapt the sample project to the desired microcontroller and create an application,some layers must be adapted to the target hardware.
All code points where adjustments are required are marked as follows:/* BEGIN OF USER CODE … *//* END OF USER CODE … */The documentation for the stack can be found in the "Interface Control Document". (https://cybermotor.wittenstein.de/de-de/download-reactionwheel)

3.5 Diagnostics using the cyber® reaction wheel assistantIn the case of a prototypical integration of the reaction wheel, see section 3.4, parallel diagnostics
with the cyber® reaction wheel assistant can be of great use. In this way, the implemented sourcecode lines in the prototypical ADCS setup can be verified using the oscilloscope, the monitor,
or simply by querying parameters in the assistant.
This can be realized very easily.
Simply follow the steps described in sections 3.3.2 and 3.3.3. This establishes a parallel
connection to the cyber® reaction wheel assistant. In this structure the cyber® reaction wheel
assistant is only intended for diagnosis. Theoretically, setpoints can be written for active control of
the reaction wheel. However, this may result in unwanted behavior.
• Parallel operation can cause a CPU load warning. This can be ignored in this case. This canbe recognized by the Warning flashing in red in the bottom of the cyber® reaction wheel
assistant.

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3.6 Firmware update
Download the required firmware package from the download portal.
3.6.1 Firmware update with the cyber® reaction wheel assistant
The update process is described in the CHM help.
For this purpose,
open the cyber® reaction wheel assistant
open the CHM-Help by pressing F1enter firmware update in the search screen•

Notice:During the firmware update, the I2C address is reset to the default value 0x77. After the
firmware update has been completed, the desired I2C address, see section 2.3.4.1,
must be restored.

3.6.2 Firmware update with ADCS
The procedure for this is described in the Interface Control Document in the
UserInterface_FirmwareUpdate() function.

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Project planning guide4 Integration of the cyber® reaction wheel 2 into a satellite
4.1 Electrical integration of the cyber® reaction wheel 2
There are identical plug connectors on two sides of the reaction wheel. All three axes of rotationof a Cartesian coordinate system can be mapped on the carrier board with only two different
mating connector arrangements (turned by 90°).
For positions of the connectors and the mounting threads, see dimensional
drawing 5007-D060499. Connector type and pin assignment are described in section 2.1.5.1.
The pin characteristic is explained in the following section 2.1.5.2.
The connecting lines to the plug connector (routing, vias, etc.) that accommodates the reaction
wheel may only be implemented as closely as possible with the reaction wheel within a radius ofapprox. 2 mm in compliance with the constraints illustrated in figure 1.23. The red border in figure
1.23 is the connector on the reaction wheel. With its housing, it protrudes beyond the connector on
the carrier board. For this reason, observe the information in the connector data sheet.
The manufacturer designation is MOLEX SlimStack PCB connector (16+2) 505066-1622.
There may not be any line on the outside of the carrier board in the remaining area below thereaction wheel (see figure 1.23, shaded area) as the solder resist does not serve as reliable
insulation. A short circuit could occur at the housing or vias on the reaction wheel.

Figure 1.23: Illustration of constraints for integration of the cyber® reaction
wheel 2 on a carrier board

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The mounting bores for the reaction wheel are at GND potential for the cyber® reaction wheel
starter kit as well as the 4 mounting bores at the corners. For integration into the satellites, themounting bores for the reaction wheel and the entire housing of the reaction wheel can be on
GND and chassis potential. This allows power to be supplied by a grounded or ground-freevoltage source. The voltage difference between chassis and GND must not exceed 30 V.
• Notice: Alternatively, the housing of the cyber® reaction wheel could be mounted isolated(connected neither to GND nor to chassis). However, we recommend connecting themounting bores with a high resistance of 100 kΩ to 1 MΩ to GND to compensate for possible
charges between GND and the housing to prevent the permitted 30 V from being exceeded.

4.2 Mechanical integration of the cyber® reaction wheel 2
The through holes for the M2 fastening screws must have a diameter of 2.6 mm. A position
tolerance of 0.2 mm for compensation of any position and length deviations of the connectors
must be observed.

4.3 Installation of the cyber® reaction wheel 2•

Observe the safety and processing instructions for the threadlocker
to be used.
•

•
•

•
•
•
•

Connect the connector of the mounting
position used with the PCB connector
on your attachment part. While doing
so, make sure that the connector is
engaged properly and not damaged.
Coat the fastening screws with athreadlocker.
Fasten the drive system with thefastening screws through the threaded
bores (A or B). When tightening,
ensure that the connector is not
subject to any lateral loads.

Use screws with property class A2-70 or titanium grade 5 and tighten them with a maximum
torque of 0.11 Nm. Also observe the load capacity of the screw head.
Use the maximum screw-in depth.
Attach the drive system so that the name plate can still be read.
Make sure that the unused second connector is protected against contact with conductive
components.

NOTICE
Fastening screws that are screwed in too far can damage thedrive system.
• Screw in the screws only up to their maximum depth.
 see dimensional drawing (5007-D060499).

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4.4 Requirements for power adapters and supply voltage
When dimensioning the power supply units, observe the electrical characteristics specified intable 4. Also take into account operation of several reaction wheels at the same time.

4.5 Installation space
The installation size must be sufficiently large.
A minimum distance of 1 mm on all sides of the drive system must be observed.

4.6 Mounting position
Any mounting position can be selected.

4.7 Cooling
Sufficient thermal conduction for cooling of the drive system must be ensured at the
installation location.

4.8 MaintenanceNo maintenance is required.

4.9 Software-side integration in ADCS
For integration of the reaction wheel into an ADCS, Wittenstein provides a communication stackincluding a sample or reference project for download.
The procedure is described in detail in section 3.4. Information on integration of the software
stack can be found in section 3.4.4.

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