3. APPLICATIONS INFORMATION
3.1 Module Mounting
The modules may be mounted in vertical or horizontal position to the user board of the
application device (load module). In a vertical position, the module pins can be directly
connected to the user board through suitable PCB holes.
Optionally suitable female strip
connectors can be used, available e.g. from Conrad Electronic GmbH (Ordering No.
73 92 43).
Additional module fixing may be necessary in rough environments.
The following features have to be available on the motherboard:
-
Load circuit, i.e. power switches or serial interface driver (connected to RCM functional
output pins OUT_0..3)
-
Power supply for the receiver module (GND_0, GND_1, VCC) and for the load circuit
-
Configuration of the receiver firmware (connecting of input pins CODE_0, CODE_1 and
CODE_2)
-
Programming pushbuttons for channel storing (connecting of input pins LRN and CLR)
-
If needed, Learn Mode indication circuitry: LED(s) for providing optical feedback and/or
a load output decoupling logic
-
External connectors
3.2 Antenna Mounting
Positioning and choice of receiver and transmitter antennas are the most important factors in
determining system transmission range. The RCM 152 receiver modules are supplied without
antenna as a standard. For mounting the antenna, the following notes should be considered to
optimize the system performance:
a) Mounting a 1/4-wave whip antenna:
A whip antenna enables a very compact receiver unit with good radio reception characteristics.
For good receiver performance, great care must be taken about the space immediately around
the antenna since this has a strong influence on screening and detuning the antenna. The
antenna should be drawn out as far as possible and must never be cut off. Mainly the far end
of the wire should be mounted as far away as possible from all metal parts, PCB strip lines and
fast logic components (e.g. microprocessors). To avoid radio frequency noise from the
motherboard, which desensitizes the receiver, PCB strip lines on the user board should be
designed as short as possible, and using PCB ground plane layer is also recommended.
Note that 868 MHz whip antennas do not show any directional effects under free-field radio-
wave propagation conditions (spot-wise radiator). The RSSI voltage output can be used for
evaluating the influence of intuitive RF optimizations.
For a good antenna performance don’t roll up or twist the whip and please draw
attention to an overall whip distance of at least 10 mm (20 mm is better) from any
PCB strip, ground plane and conductive part or electric part.
©EnOcean GmbH
Page 14 of 20
RCM 152 User Manual V1.31
