Issue
93 April 1998
Picaro:
A Stamp-like Interpreted Controller
by
Tom Napier
For
years, Tom’s been itching to control the instruction
sets of processors. Using a PIC, some memory, and
an interpreter, he bypasses the processor hurdle
and writes his own language. He shows you how to
do it, too.
System
resourceS
In
case you are interested in setting up a similar system,
you can download the source code for the PLU. However,
I didn’t include code for the ODU. It is intertwined
with the application software and would have been difficult
to use in that form.
The
PLU takes only a few hundred lines of assembler code,
which translates to about 750 bytes of storage on your
typical 8-bit micro. In terms of execution time, the
worst-case condition takes about 1800 instructions.
On
an 8031 running at 12 MHz, that equates to about 5 ms
to run the PLU thread. This light load is further eased
by the fact that the bulk of the PLU thread only runs
once per day for an execution overhead of roughly 0.0000057%.
So, the PLU can be easily integrated into an application
without adding too much of a burden on system resources.
Hopefully,
now you see how straightforward it is to set up intelligent
building-control applications, and you’re ready
to take us into those smart buildings we’ve heard
so much about for so long.
Beau
Wadsworth has been designing embedded systems since
1983. His company designs and manufactures products
on an OEM basis for the security and home automation
industry. You may reach Beau at (423) 689-8851 or via
E-mail at b_wadsworth@nxs.net.
