EKF SC4-CONCERTO, Руководство пользователя

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User Guide • SC4-CONCERTO • CompactPCI
®
Serial CPU Board
Watchdog
An important reliability feature is a software programmable watchdog function. The SC4-CONCERTO
contains two of these watchdogs. One is part of the CM238 PCH and also known as TCO Watchdog.
A detailed description is given in the CM238 data sheet. Operating systems like Linux offer a driver
interface to the TCO watchdog.
The behaviour of the 2
nd
watchdog is defined within a PLD of the SC4-CONCERTO, which
activates/deactivates the watchdog and controls its time-out period. The time-out delay is adjustable
in the steps 2, 10, 50 and 255 seconds. After programming the time-out value and arming the WD,
the related software (e.g. application program) must trigger the watchdog periodically. For details on
programming the watchdog see section “Board Control and Status Register (BCSR)”.
This watchdog is in a passive state after a system reset. There is no need to trigger it at boot time. The
watchdog is activated on the first trigger request. If the duration between two trigger requests
exceeds the programmed period, the watchdog times out and a full system reset will be generated.
The watchdog remains in the active state until the next system reset. There is no way to disable it once
it has been put on alert, whereas it is possible to reprogram its time-out value at any time.
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