Timer processors
An alternative to using a timer/counter is the development of timer
computers where a processor is used exclusively to manage and implement complex
timing functions over multiple timer channels. The MC68332 is a good example of
such a proces-sor. It has a CPU32 processor (MC68020 based) running at 16 MHz
and a timer processor unit instead of a communications processor. This has 16
channels which are controlled by a RISC-like processor to perform virtually any
timing function. The timing resolution is down to 250 nanoseconds with an
external clock source or 500 nanoseconds with an internal one. The timer
processor can per-form the common timer algorithms on any of the 16 channels
without placing any overhead on the CPU32.
A queued serial channel and 2 kbits of power-down static RAM are also
on-chip and for many applications all that is re-quired to complete a working
system is an external program EPROM and a clock. The timer processor has
several high level functions which can easily be accessed by the main processor
by programming a parameter block. For example, the missing tooth calculation
for generating ignition timing can be easily performed through a combination of
the timer processor and the CPU32 core. A set of parameters is calculated by
the CPU32 and loaded into a parameter block which commands the timer processor
to perform the algorithm. Again, no interrupt routines or periodic peripheral
bit manipulation is needed by the CPU32.
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