RFXCOM RFXtrx433 Spezifikationen PDF herunterladen (Seite 88)

LIST OF FIGURES 81

3.3. The software part of the communication chain, which contains three ROS Nodes.

ROS serves as a link between the nodes connecting them and oﬀering the interfaces

for the IE. The gateway, however, is not directly connected to ROS; instead it is

connected to the gateway driver node, which allows indirect access over ROS. . . 29

3.4. The information chain in more detail: Each node abstracts the data a bit further

allowing to convert the initial binary data into human readable information. . . . 31

3.5. A remote control switches a light on. The gateway receives the on-code and its

data ﬂows through the gateway driver to the device manager, where the entries of

the remote control and light are updated (marked with arrows). These changes

are delivered to the visualization node and are ﬁnally outputted as a simpliﬁed

namespace and device state message. . . . . . . . . . . . . . . . . . . . . . . . . 32

3.6. The diﬀerent transmission times and actions per second. The grey boxes rep-

resent the worst case, when only the minimal numbers of required packages are

received successively. This can happen when multiple signals from diﬀerent devices

superimpose. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

4.1. The structure of WiﬁControl 433: The centerpiece is an Atmel ATXMega192A3,

an 8 bit microcontroller, which is connected to peripheral hardware, such as a WIFI

module, a USB-serial bridge and a 433 MHz radio. . . . . . . . . . . . . . . . . . 37

4.2. The WiﬁControl 433 with its diﬀerent functional units. . . . . . . . . . . . . . . 37

4.3. The program core on the left and the priority table on the right. . . . . . . . . . 38

4.4. The WiﬁCtrl on the left and the MiniCtrl without its antenna on the right. Both

models were generated by eagle3d and rendered with MegaPOV. . . . . . . . . . 39

4.5. The old USB circuit (top) and the newer circuit with EMI ﬁltering and the IC

PRTR5V0U2X for ESD protection (bottom). . . . . . . . . . . . . . . . . . . . 40

4.6. The ceramic antenna on the left and the PCB antenna on the right. Both pi-ﬁlters

are bypassed. The yellow colour of the left PCB is due to the lack of solder resist. 41

4.7. The signal chain in detail: The RFM22B receives incoming data and sends it to

the MCU, where it is ﬁltered by a deglitching algorithm and ﬁnally processed. The

conﬁguration bus is composed of a SPI and several IO-pins and used for controlling

the RFM22B. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42

4.8. The simpliﬁed internal structure of the RFM22B in receiving mode: Incoming

signals are ampliﬁed at ﬁrst and then ﬁltered by a low-pass ﬁlter. A comparator

compares the signal with a reference voltage from an integrator and outputs a

binary data stream. The integrator circuitry is also called automatic gain control

(AGC) as it generates a dynamic reference voltage to increase the overall sensitivity. 43

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RFXCOM RFXtrx433 Spezifikationen Seite 88