Zippy Tech. HG2 Manual de usuario descargar pdf (Pagina 36)

24 Functional Description

3.2 Peripherals

The following standard peripherals are available on the CT-30

board:

Timer

The CT-30 is equipped with the following timers:

Real-Time Clock

The real-time clock performs timekeeping functions and

includes 256 bytes of general purpose CMOS RAM. Features

include an alarm function, programmable periodic interrupt and

a 100-year calendar. All CMOS RAM data remains stored in an

additional EEPROM to prevent data loss.

Counter/Timer

Three 8254-style counter/timers are included on the CT-30 as

defined for the PC/AT (System Timer, Refresh Request,

Speaker Tone Output).

In addition to the three 8254-style counters, the IICH includes

three High Precision Event Timers (HPET) that may be used by

the operating system. They are implemented as a single

counter each with its own comparator and value register. They

support One-shot and periodic interrupts.

Watchdog Timer

The CT-30 provides a Watchdog Timer that is programmable for a

timeout period ranging from 1 ms to 1050 sec. Failure to trigger

the Watchdog Timer in time results in a system reset, an interrupt,

or NMI. In the dual-stage mode, a combination of both NMI, and

reset if the Watchdog is not serviced. A hardware status flag will

be provided to determine if the Watchdog Timer generated the

reset.

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Zippy Tech. HG2 Manual de usuario Pagina 36