Radiometrix Ltd
TR2M Data Sheet
page 4
Figure 4: TR2M interfaced to host microcontroller and serial port for configuration
TR2M can be directly interfaced to a host microcontroller which can generally be powered by the
regulated +4.4V output on pin 8 of TR2M. Three I/O pins on the microcontroller port can be assigned to
select the first 8 channels on frequency table of the appropriate band for which the module is configured
by pulling the P1-P3 pins low. Channel select pins of TR2M have internal pull-up to 4V supply rail,
hence channel selection operate on inverted logic.
Channel
P3:P2:P1
433MHz band
458MHz band
0
111
433.050
458.525
1
110
433.075
458.550
2
101
433.100
458.575
3
100
433.125
458.600
4
011
433.150
458.625
5
010
433.175
458.650
6
001
433.200
458.675
7
000
433.225
458.700
Digital Received Data Output (RXD) pin is an open collector output, which should be pulled-up to
required voltage swing level (e.g. +4.4V or Vcc).
TR2M has an automatic noise squelching function which is activated when there is not any RF signal at
detectable level on the channel or if the non-coherent noise like interference level is high enough to
block any weak RF signal from being received. SQF is provided as an open-collector output for
monitoring which should be pulled-up to required voltage swing level. SQF output will jump to pull-up
voltage level if received RF signal level at the RF In/Out pin of the module is about 3dB below the level
required to produce 12dB SINAD level on demodulated AF Output signal. SQF pin can be connected to
an LED to act as a Carrier Detect indicator. Pull-up resistor value should be reduced (e.g. 1kΩ)
according to the current requirement to produce satisfactory brightness on the LED used.
TR2M can be configured using any PC/Laptop/PDA having a serial port and modem/terminal program.
TXD (pin 3) of DB9M connector can be directly wired to PGM (pin C10) of the TR2M and SGN (pin 5) of
DB9M connector should be either connected to common ground or pin C9 of the TR2M.
The whole frequency/channel table is user reconfigurable to 128 channels within 5MHz band of supplied
frequency subject to regulatory band limits. Serial Channel Selection via PGM pin gives access to the
whole of regulatory band allocation for 433.05MHz-434.790MHz (69 channels) or 458.525MHz-
458.925MHz (23 channels).
TXE (MOD TX_ON) (C1)
TXD (MOD NC) (C2)
AF in (MOD NC) (C3)
RSSI (C4)
SQF (MOD NC) (C5)
AF out (C6)
RXD (MOD NC) (C7)
+4.4V out (C8)
GND (C9)
PGM (C10)
P1 (MOD TXD) (C11)
P2 (MOD RXD) (C12)
P3 (MOD NC) (13)
10kΩ
100nF
Carrier Detect
1
2
3
TXD
SGD
4
6
7
8
9
5
ADC
Transmit Enable
Data Out
Data In
VDD
Parallel
Channel
Select
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