Project planning guide
cyber
®
reaction wheel 2
en-32
Doc. no.: 5022-D060586
Revision: 02
3.4.3 Communication interfaces
The cyber
®
reaction wheel 2 offers the following communication interfaces as an interface to
a 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 the
cyber
®
reaction wheel 2. With a simple structure, several reaction wheels can be integrated in
parallel 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 and
deceleration either synchronously or asynchronously to the reaction wheels. For the normally
prioritized synchronous setpoint transmission, the reaction wheel uses the broadcast message at
address 0x0 at the I2C bus.
•
When this combination is used, it must be ensured that this message does not interfere with
other I2C participants or that they do not interfere with it.
Figure 1.21: Schematic integration of several starter kits with reaction wheels for startup of all interfaces with multiple axes
SPI
I2C
UART
µC PCB, e.g. Eval Board
for ADCS
Wittenstein
Stack
ADCS
software
