Pin description of BHX2 with Modem mode selected
The 'modem' mentioned is a 1200 baud RS232 semi-intelligent unit (Transmit keyed when valid
serial data is present, so no separate TX control needed. Coding in the datastream also permits
the receiver to ignore noise and only output valid serial data). This is a half duplex unit, so
collisions between transmitted and received packets must be dealt with by the user.
Pin
1
Name
MOD TX_ON
Function
Open = normal modem operation. Low = constant TX (for test). 10k
pullup to 4V
Leave open
2
3
4
MOD NC
MOD NC
RSSI
Leave open
DC level between 0.5V and 2.5V. 60dB dynamic range
5
6
7
MOD NC
AF out
NC
Leave open
Modem tones or noise present
Leave open
8
9
10
11
12
13
+4.4V out
0V
PGM
MOD TXD
MOD RXD
MOD NC
Regulated DC supply. 75mA max. drain. Present if unit is powered
Ground
Serial programming/configuration input at RS232 level
RS232 data input (true). 10k pullup to 4V
Inverted RS232 data out (to inverting buffer like MAX232)
Leave open
BHX2s on both ends should be configured to required operating frequency using
GOCHAN command before starting to use the internal 1200 baud modem, because the
P1-P3 pins will be used as Modem Data pins and the modem will operate on the last
serially selected channel after SETMOD command is used to enable the Modem.
TXE(MOD TX_ON) (1)
TXD (MOD NC) (2)
AFin (MOD NC) (3)
RSSI (4)
SQF(MOD NC) (5)
AFout (6)
Serial COM Port
RXD (MOD NC) (7)
+ 4.4Vout (8)
GND (9)
1
2
6
7
8
9
BHX2
RXD
TXD
PGM (10)
3
SW1
P1 (MOD TXD) (11)
P2 (MOD RXD) (12)
P3 (MOD NC) (13)
VDD
4
5
SGD
RS232 driver
Figure 6: BHX2 interfaced to PC serial port in modem mode
Note:
Baud rate used for Modem is half that of used for serial configuration. Attached RS232
devices should be set with the following:
1200bps, 8 Data bits, No Parity, 1/2 stop bits, no flow control
TXD (Pin 3) of a Serial Port can be switched from PGM (Pin C10) to MOD TXD (Pin C11)
with no RS232 driver in between. However, MOD RXD (Pin C12) requires an RS232 line
driver before it can be connected to RXD (pin 2) of a serial port. Some of the RS232 line
drivers can be powered from the regulated +4.4V out (Pin C8).
Radiometrix Ltd
BHX2 Data Sheet
page 7
RADIOMETRIX [ RADIOMETRIX LTD ]
