User`s guide

T-MOPSlcdSA User's Guide
Keyboardand Feature Interface 23
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11.3 Known Issues
A problem occurs when the SHIFT, NUMLOCK, ROLL or CAPSLOCK key is pressed, which will update
the keyboard LED's via command EDh. The STPC does not acknowledge this and will send a beep to
the speaker output.
The keyboard controller also sends several beeps when booting a DOS operating system without a
PS/2 keyboard connected to the system.
11.4 Signal Descriptions
11.4.1 /RESIN and PWRGOOD (Reset Inputs)
 Input on CPU modules
 When POWERGOOD goes high, it starts the reset generator on the CPU module to pull
the onboard reset line high after a valid reset period. You also can use this pin as a low
active hardware reset for modules.
11.4.2 Speaker
 Open collector output on modules that drive a piezo electronic speaker.
 Input on modules that connects a 5V piezo electronic speaker to this pin.
 An 8-Ohm loudspeaker also can be connected between SPEAKER and GND, but because
of current limitation, the volume will be low.
 Connect only one speaker to this pin. The CPU usually drives this pin. However, other
modules also can use this signal to drive the system speaker.
11.4.3 KBDAT (Keyboard Data)
 Bi-directional I/O pin on CPU modules
 Keyboard data signal
11.4.4 KBCLK (Keyboard Clock)
 Bi-directional I/O pin on CPU modules
 Keyboard clock signal