CM1481 Datasheet, PDF (5/24 Pages) ON Semiconductor – 2-Channel EMI Filter with ESD Protection for Headsets/Speakers

Installation ......
CM1481 Radio Interface
The table below shows the functions and interconnections of the CM1481 interface (J1) employed in both NORMAL
and CONFIGURATION modes.
Functions prefixed by a star (*) indicate configurable IN/OUT polarities. Consult the Configuration section of this
manual for Configuration Instructions and Configuration Interface Connector termination information.
Pin Function
1
CONFIG
2
* BUSY
Normal Mode - to Radio
Function Configure Mode - to PC
Configuration mode sense. When this pin is “High” the module WILL NOT enter the CONFIGURATION
mode, when “Low” the module WILL enter the CONFIGURATION mode on power-up.
Input from the radio squelch circuitry. A level here
indicates the presence of an RF carrier.
3 * Tx CALL Input from the installation “Operation” momentary- CLOCK The CLOCK signal generated by
action switch to initiate a Selcall.
the configuring PC is input here.
See "Single/Dual Button" Operation notes.
4 * QUIET/OPEN Input from the installation “Operation” momentary- DATA IN
action switch to control the radio mute state.
See "Single/Dual Button" Operation notes.
Data from the configuring PC to the
module is input here.
5
* PTT IN
Input from the Mic. or peripheral PTT line.
The CM1481 controls the radio Tx function via
Tx On.
6 SIGNAL IN Input for received Selcall tones from the radio
demodulator prior to squelch circuitry.
7
ALERT
Audible alerts output. Introduce into the radio's Rx
audio stage with due regard to any audio powersave
functions. This output can drive a loudspeaker directly.
8
* LED
Output drive to an LED indicator.
Connect an LED between this pin and GND.
DATA OUT Data from the module to the
configuring PC is output here.
9 TONE OUT Selcall tone output. Introduce this output into the
radio Tx Audio path.
10 * MUTE CTRL Connect to radio Rx Squelch circuitry so that when
this output is active Rx Audio is muted.
11 * Tx ON
Tx PTT Drive. When active this output will key the Tx.
12
GND
Signal Ground (-)
13
V IN
Positive Supply Voltage (+)
AUDIO SWITCH An on-board (Audio Signalling Processor) all-audio switch-path, accessible via on-board
solder-pads. This switch operates in co-ordination with the QUIET/OPEN function for use with all audio
signals. When 'Quiet' the switch is OFF, when 'Open' the switch is ON.
Table 1 CM1481 Radio Interface Functions
The position of Pin 1 is identified on Figure 4 (PCB Layout).
5