Programmable Timers; Interval Timers; 16/32-Bit Timers - Motorola MVME2301 Installation And Use Manual

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 Raven 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:
The interval timers use the OSC clock input as their clock source.
The MVME230x drives the OSC pin with a 14.31818MHz clock
source.

16/32-Bit Timers

There is one 16-bit timer and four 32-bit timers on the MVME230x.
The 16-bit timer is provided by the PIB. Raven device provides the
four 32-bit timers that may be used for system timing or to generate
Two software interrupts
ISA interrupts (actually handles as a single 8259 interrupt at
INT0)
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 MVME230x.
Counter 2 provides the tone for the speaker output function
on the PIB controller (the
cabled to an external speaker via the remote reset connector).
This function is not used on the MVME230x.
Functional Description
signal which can be
SPEAKER_OUT
3
3-19