Utility Connector
Utility Connector
K
EYBOARD
/M
OUSE
I
NTERFACE
A standard PS/2 keyboard and mouse interface is accessible through connector JS4. In addition,
you will find a programmable LED output, hard drive activity LED, and a speaker output as
shown in the table below. The pinout of the PS/2 connectors applies to use of the VersaLogic
transition cable #VL-CBL-8001.
This connector is protected with IEC 61000-4-2 (Level 4) rated TVS components to help protect
against ESD damage.
Table 11: Utility Connector
JS4
Pin
Description
PS/2
Pin
27A
Programmable LED +
28A
Programmable LED –
29A Speaker
+
30A Speaker
–
31A
IDE Drive Indicator LED –
32A
IDE Drive Indicator LED +
33A Protected
+5V
4
34A Mouse
Data
1
35A Ground
3
36A Mouse
Clock
5
37A Protected
+5V
4
38A Keyboard
Data
1
39A Ground
3
40A Keyboard
Clock
5
(JB) Mouse
Connector
(JC) Keyboard
Connector
P
ROGRAMMABLE
LED
The high-density I/O connector JS4 includes an output signal for attaching a software controlled
LED. Connect the cathode of the LED to JS4[28A]; anode to JS4[27A]. An on-board resistor
limits the current to 15 mA when the circuit is turned on.
To turn the LED on and off, set or clear bit D7 in I/O port 0E0h (or 1E0h if selected in CMOS
Setup). When changing the register, make sure not to alter the value of the other bits.
The following code examples show how to turn on and off the LED. Refer to page 41 for further
information:
LED On
LED Off
in
al,E0h in
al,E0h
or
al,80h and al,7Fh
out E0h,al out E0,al
Note!
The LED is turned on by the BIOS during system startup. This causes the light to
function as a "power on" indicator if it is not otherwise controlled by user code.
EPM-CPU-10 Reference Manual
Reference – 29