17 PCA-6781 User Manual
Chapter 2 Installation
2.15 HDD LED/Reset/Power Button (CN1)
Next, you may want to install external switches to monitor and control the PCA-6781.
These features are optional: install them only if you need them. CN1 is an 2 x 5 pin
header, 180 degree, male. It provides connections for reset and power & hard disk
indicator.
2.15.1 HDD LED (Pin 1&Pin 2)
The HDD LED indicator for hard disk access is an active low signal (24 mA sink rate).
2.15.2 POWER LED (Pin3 & Pin4)
+5 V POWER LED indicator would light when the power is on.
2.15.3 Suspend led (PIN 5&Pin 6)
Suspend led indicator would light when the computer is suspend.
2.15.4 Reset (Pin7&Pin8)
If you install a reset switch, it should be an open single pole switch.
Momentarily pressing the switch will activate a reset. The switch should
be rated for 10 mA, 5 V.
2.15.5 Power Button (Pin9&Pin10)
PCA-6781 also supports power on/off button.
2.16 COM port Connector (CN14,CN15)
The PCA-6781 provides two COM ports (COM1: RS-232 and COM2: RS-232/422/
485). CN14 supports COM2, CN15 supports COM1. And J5 is for COM RS-232/422/
485 selection. It provides connections for serial devices (a mouse, etc.) or a commu-
nication network. You can find the pin assignments for the COM port connector in
Appendix B.
2.17 MINI Keyboard Connector (CN19)
The PCA-6781 board provides a keyboard connector that supports both a keyboard
and a PS/2 style mouse. In most cases, especially in embedded applications, a key-
board is not used. If the keyboard is not present, the standard PC/AT BIOS will report
an error or fail during power-on self-test (POST) after a reset. The PCA-6781’s BIOS
standard setup menu allows you to select "All, but Keyboard" under the "Halt
On"selection. This allows no-keyboard operation in embedded system applications,
without the system halting under POST.
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