SMC Networks 1232 Series User Manual

 

 

 

 

 

 

18

 

 

 
Below is shown the connector pinout: 

Table 3. 

Multifunction connector 

SPKR-

Speaker output 

2  SPKR+

Speaker output (+5V) 

3  RESET

External reset 

WDTL

Watch dog timeout latch

KBD 

Keyboard data 

KBC 

Keyboard clock 

GND 

Ground signal 

KBP 

Keyboard power (+5V) 

BAT 

External Battery input 

P_B 

External Power Button 

 
 
 
This section of the connector implements the following functions: 
 

ƒ  Keyboard 

An AT compatible keyboard can be connected to the module through connector J3. The 
following table lists the pin-out of connector J3. 

Table 4. 

Keyboard connector  

KBD 

Keyboard data 

KBC 

Keyboard clock 

GND 

Ground signal 

+5V 

Power supply 

 
 

ƒ  System reset 

Connecting the pin 3 of the multifunction connector to ground performs a hardware reset 
of the module. It is possible to use an external push-button, normally open. J3 provides a 
connection for an external normally-open pushbutton to manually reset the system. 
Connect the other side of the switch to ground. The reset signal is “de-bounced” on the 
board. 

 

ƒ  External Battery 

Pin 9 of the multifunction connector allows the connection of an external backup battery 
(typically from 3 to 3.9 V). This battery is used at power down to preserve the date-time in 
the Real Time Clock. 
The typical battery consumption with the module off is 7 uA. 
 

ƒ  Speaker 

A transistor to supply 0.1 watt of power to an external speaker controls these outputs. A 
transistor amplifier buffers the speaker signal. Use a small general purpose 2 or 3-inch 
permanent magnet speaker with an 8-ohm voice coil.