Motorola MVME2400 manual Interrupt Controller Mpic, Programmable Timers, Interval Timers

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Functional Description

Interrupt Controller (MPIC)

The MPIC Interrupt Controller portion of the Hawk ASIC is designed to handle various interrupt sources. The interrupt sources are:

❏Four MPIC timer interrupts

❏Processor 0 self interrupt

❏Memory Error interrupt from the SMC

❏Interrupts from all PCI devices

❏Two software interrupts

❏ISA interrupts (actually handles as a single 8259 interrupt at INT0)

Programmable Timers

Among the resources available to the local processor are a number of programmable timers. Timers are incorporated into the PCI/ISA Bridge (PIB) controller and the Hawk device (diagrammed in Figure 3-1). They can be programmed to generate periodic interrupts to the processor.

Interval Timers

The PIB controller has three built-in counters that are equivalent to those found in an 82C54 programmable interval timer. The counters are grouped into one timer unit, Timer 1, in the PIB controller. Each counter output has a specific function:

❏Counter 0 is associated with interrupt request line IRQ0. It can be used for system timing functions, such as a timer interrupt for a time-of-day function.

❏Counter 1 generates a refresh request signal for ISA memory. This timer is not used in the MVME240x.

❏Counter 2 provides the tone for the speaker output function on the PIB controller (the SPEAKER_OUT signal which can be cabled to an external speaker via the remote reset connector). This function is not used on the MVME240x.

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