BHX2_12 Datasheet, PDF (4/9 Pages) Radiometrix Ltd – NBFM Multi-channel 500mW UHF Transceiver

TXE (MOD TX_ON) (1)
TXD (2)
AF in (3)
RSSI (4)
SQF (5)
AF out (6)
BHX2 RXD (7)
+ 4.4V out (8)
GND (9)
PGM (10)
P1(11)
P2 (12)
P3 (13)
Transmit Enable
Data Out
ADC
Carrier Detect
Data In
10kΩ
VDD
100nF
Parallel
Channel
Selec t
1
6
2
73
8
4
9
5
TXD
SGD
Figure 4: BHX2 interfaced to host microcontroller and serial port for configuration
BHX2 can be directly interfaced to a host microcontroller which can generally be powered by the
regulated +4.4V output on pin 8 of BHX2. 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 BHX2 have internal pull-
up to 4V supply rail, hence channel selection operate on inverted logic.
Channel
0
1
2
3
4
5
6
7
P3:P2:P1
111
110
101
100
011
010
001
000
458MHz band
458.525
458.550
458.575
458.600
458.625
458.650
458.675
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).
BHX2 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.
BHX2 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 BHX2 and
SGN (pin 5) of DB9M connector should be either connected to common ground or pin C9 of the
BHX2.
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 458.525MHz-458.925MHz (23 channels).
Radiometrix Ltd
BHX2 Data Sheet
page 4