SMC Networks 1232 Series ƒ Keyboard, Pin Signal, +5V, ƒ System reset, ƒ External Battery

Below is shown the connector pinout:

Table 3. Multifunction connector

Pin	Signal	Function
1	SPKR-	Speaker output
2	SPKR+	Speaker output (+5V)
3	RESET	External reset
4	WDTL	Watch dog timeout latch
5	KBD	Keyboard data
6	KBC	Keyboard clock
7	GND	Ground signal
8	KBP	Keyboard power (+5V)
9	BAT	External Battery input
10	P_B	External Power Button

This section of the connector implements the following functions:

ƒKeyboard

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.

Pin Signal

5	KBD
6	KBC
7	GND
8	+5V

Keyboard connector

Function

Keyboard data

Keyboard clock

Ground signal

Power supply

ƒSystem 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.

ƒExternal 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.

ƒSpeaker

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.

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