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PCA-6774 User Manual 22
2.19 ATX Power & HDD LED, speaker out Connector
(CN16, CN17, CN19)
Next, you may want to install external switches to monitor and control the
PCA-6774. These features are optional: install them only if you need
them. CN16, CN17, CN19 integrated in one connector, which is an 5 x 3
pin header, 180degree, male. It provides connections for a speaker, hard
disk access indicator.
2.19.1 HDD LED (CN19)
The HDD LED indicator for hard disk access is an active low signal
(24mA sink rate).
2.19.2 ATX power LED & KB-LOCK (CN16)
Power supply activity LED indicator and KB_lock function.
2.19.3 Speaker out (CN17)
Support a buzzer function, pin assignment refer to Appendix B.
2.20 COM port connector (CN9,CN10,CN29)
The PCA-6774 provides two serial ports (COM1: RS232 and COM2:
RS422/485) in one COM port connector. It provides connections for
serial devices (a mouse, etc.) or a communication network. You can find
the pin assignments for the COM port connector in Appendix B.
2.21 Keyboard and PS/2 mouse connector (CN11)
The PCA-6774 board provides a keyboard connector that supports both a
keyboard and a PS/2 style mouse. In most cases, especially in embedded
applications, a keyboard 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-6774'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.
2.22 External KB/mouse connector (CN12)
In addition to the PS/2 mouse/keyboard connector on the PCA-6774's
rear plate, there is an additional onboard external keyboard connector,
allowing for greater flexibility in system design.