Programmable Timers; Interval Timers; 16/32-Bit Timers - Motorola MVME2400 Series Installation And Use Manual

Functional Description

Programmable Timers

3

Interval Timers

16/32-Bit Timers

3-26
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
3-4). They can be programmed to generate periodic interrupts to the
processor.
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
external speaker via the remote reset connector). This function is not
used on the MVME240x.
The interval timers use the OSC clock input as their clock source. The
MVME240x drives the OSC pin with a 14.31818 MHz clock source.
There is one 16-bit timer and four 32-bit timers on the MVME240x. The
16-bit timer is provided by the PIB. The Hawk device provides the four 32-
bit timers that may be used for system timing or to generate periodic
interrupts. For information on programming these timers, refer to the data
sheet for the W83C553 PIB controller and to the MVME2400 Series VME
Processor Module Programmer's Reference Guide.
signal which can be cabled to an
SPEAKER_OUT
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Figure 3-1 on page