Wavenet Technology Pty Ltd. BM2900D Benutzerhandbuch

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Boomer II User Manual & Integrator’s Guide _________________________________________________Installation 
 
BM210012WT37 
37 
Copyright Wavenet Technology © November 2003 
LED Output Lines 
In addition to the on-board LED’s there are three signal lines (Low 
Battery, Message Waiting, In-range), which are controllable by the 
modem for connection to an external LED. Each line has a 33Ω series 
resistor and clamp diode to the internal supply line for protection. It is 
recommended a series resistor be used with the external LED to limit 
current accordingly. The electrical interface capability, equivalent 
circuit and operation of these lines is summarized in the tables below: 
LED Output Lines Equivalent Circuit 
 
LED Interface Electrical Characteristics 
Parameter Range  Low High 
Output Voltage 
0 – 3.3 V 
0.5 V (max) 
2.3 V (min) 
Output Current 
 
3.2 mA (max) 
1.6 mA (min) 
 
 
Note: DCD and INRANGE outputs share the same output line from the 
microprocessor and therefore the combined current consumption of 
that line must not exceed 2mA. 
LED Interface Definitions 
J1 
Pin # 
Signal Description 
Signal 
Active 
State 
13 
LED
0_
MSGWTG
 
Message 
waiting 
Output 
Low when message waiting 
14 
LED
1_
INRANGE
 
In range 
Output 
Low when modem in-range 
15 
LED
2_
LOWBAT
 Low 
battery Output 
Low when battery is less than 
3.5V,  
High when battery is greater 
than 3.6V 
 
Low Battery 
The Low Battery signal is held active low whenever the supply voltage 
drops below an acceptable level (less than 3.5V) and deactivated when 
the voltage level becomes acceptable again (greater than 3.6V).  The 
transitions will occur at the same time as the low battery event occurs 
(or would occur if the event was activated).  Note that in the case of a