Interval Timers; 16/32-Bit Timers - Motorola MVME2300 Series Installation And Use Manual

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
MVME2300 drives the OSC pin with a 14.31818 MHz clock source.

16/32-Bit Timers

There is one 16-bit timer and four 32-bit timers on the MVME2300. 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 periodic
interrupts. For information on programming these timers, refer to the data
sheet for the W83C553 PIB controller and to the MVME2300 Series VME
Processor Module Programmer's Reference Guide.
3-19
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 MVME2300.
Counter 2 provides the tone for the speaker output function on the
PIB controller (the
SPEAKER_OUT
external speaker via the remote reset connector). This function is not
used on the MVME2300.
Block Diagram
signal which can be cabled to an
3