User guide

User Guide CC8-BLUES • Multi-Processing CompactPCI CPU
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EKF Elektronik GmbH • Philipp-Reis-Str. 4 • 59065 HAMM • Germany
Tel. [phone] • Fax. [phone] • E-Mail [e-mail] • Internet http://www.ekf.de
Watchdog/Reset
The CC8-BLUES is provided with the MAX705 supervisor circuit, which controls the supply
voltages 3.3V, 5V and the CPU core voltage, and generates a power-on reset signal. The manual
push-button reset is also passed through the MAX705 for appropriate pulse conditioning.
The reset manual push-button is situated at the front panel. The button is indent mounted
behind the front and requires a tool, e.g. pen to be pressed, preventing from being inadvertently
activated. The push button reset signal is routed across a PLD (programmable logic device) and
could be passivated on customers request.
The healthy state of the CC8-BLUES is signalled by the LED PWR integrated into the reset push-
button. As soon as this LED begins to shine all power voltages are well and the reset signal was
deasserted.
Another feature is the watchdog function, which can be be programmed by software. The
behaviour of the MAX705 watchdog is partially defined by the PLD, which controls whether the
watchdog is activated. The related software (e.g. BIOS, application program) must trigger the
watchdog by toggling the GPIO21 signal of the ICH 82801.
The watchdog is in a passive state after a system reset. There is no need to trigger it at boot
time. Once the GPIO21 of the ICH was pulsed the watchdog is activated. If the duration
between two trigger pulses exceeds a period of 1000 ms the watchdog timed out and a system
reset is generated.
The watchdog remains in the active state until the next system reset. There is no way to disable
it once it was started.