Transceivermodule 1 TRX433-10A / TRX868-10A (Vers. 1.0E ...

Transceivermodule 6 TRX433-10A / TRX868-10A (Vers. 1.0E)
Linkcontrol mode
Pin 9 (TEST) of the Transceivermodule has two functions, one for the flow-control (handshake) and the
second function is the link-control. The link-control signals a valid, bidirectional link to a second partner-
Transceivermodule.
If TEST is set high through a resistor, the status of the radio-link to the partnermodem is output on the signal
LINK\.
LINK\ low means radio communication is OK
LINK\ high means no radio communication
Because TEST as well as LINK\ are double used and depending on the application are used as an input or
an output, please take care not to connect two outputs without any current-limitation resistor together and
also prevent the situation of an open input.
As an example we refer to the application schematic of the Evalkit3, where the link-control is realized with a
push-button and a LED.
Important notice:
Pin 9 must be connected with a Pulldown resistor (e.g. 100 k) to GND, so that the configuration mode cannot
be activated unintentional during powerup of the Transceivermodule.
If during powerup pin 9 is already high, the configuration mode is activated.
RSSI (Received Signal Strenght indicator)
The voltage at pin 8 (RSSI) is directly proportional to the receiving field intensity. The higher this voltage is
the higher is also the receiving field intensity. The scaling is approx. 29dB/V, the offset or zero point is not
calibrated and depends on the RF-mode.
Powersupply
The Radiotransceiver needs a clean supply voltage of min. 3.5V with a ripple of < 10mVpp.
The power amplifier of the radio transmitter is directly connected to the input supply voltage, the rf-transmitter
power therefore depends a little on the input supply voltage.
If the supply of the Transceivermodule is switched, the voltage must always sink to 0V, before switching on
the supply again. The supply voltage must rise within max. 50ms from 0V to 3.5V, so that the integrated
microcontroller starts correctly. The voltage may never fall below 3.3 V, not even for a short time.
If this cannot be ensured, the supply voltage must be supervised by a Voltagedetector, which ties the MCLR\
input low as soon as the voltage drops below approx. 3.3V. See also application example with Evalkit3.
Datainterface with 5V Systems
The logic levels of the Transceivermodule are 3.3 Volt, according to the int. voltage regulator. The
Transceiver can work directly at 5Volt systems, however during the high level of the 5V system an additional
small current flows over the internal series resistors into the Transceiver. The input high-levels of the 5V
system must be compatible to the 3.3V logic. See also simplified schematic of the Transceiver
MCLR\ Reset
The microcontroller of the Transceivermodule hasn’t got an internal Reset-detector, so the reset pin is
externally accessible. We recommend an external Voltage detector with a trip voltage of > 3.3Volt (for
standard TRX with 3.3V internal voltage regulator). If no such detector is used, please read the datasheet of
the Microchip 16LF648A and ensure that the supply voltage conditions for powerup, brownout etc. can be
met. The most problematic situation exists, when the supply voltage drops below 3.5 Volt and then again
rises to normal condition, without going to nearly zero Volt.
Anyway, with an external voltage detector, these problems are solved.
If the conditions described under paragraph Powersupply are all met, the external reset-controller or voltage
detector can be omitted.