What Next? 295Experiment 34: Hardware Meets SoftwareSupplies
Figure 5-122 shows some of the chips in the PICAXE range. I’ll be telling you
how to use the smallest—the 08M—which costs less than $5 and is cheaper
than any other MCU that I’ve found. It has only 256 bytes of memory to store a
program (not gigabytes, megabytes, or kilobytes, just 256 bytes!), but you’ll be
surprised how many possibilities this amount allows for. Figure 5-123 shows
a closeup of the 08M with its legs safely embedded in a piece of conductive
foam.
In the United States, there are three distributors of this chip:
I like P. H. Anderson for its grass-roots hobbyist approach, and they have good
prices if you want to buy multiple chips. But SparkFun Electronics offers other
associated products that you may find interesting.
All the distributors will want to sell you “starter kits,” such as the one in Figure
5-124, perhaps because the PICAXE itself is so cheap that it doesn’t offer much
of a profit margin. Still, for our purposes, you should buy the chip as a stand-
alone item. And buy two of them, just in case you damage one (for example,
by connecting voltage to it incorrectly).
Figure 5-123. When supplied by one of its
American distributors, a PICAXE 08M
arrives embedded in a little square of
conductive foam. The chip is the same size
as a 555 timer but has the power of a tiny
computer.
Figure 5-124. A typical PICAXE kit includes
a printed circuit board, which you may not
really need, and some other not-entirely-
essential items. But the 3.5-mm stereo
jack socket (top, center) is absolutely
necessary.To download your programming instructions into the chip, first you’ll type the
instructions on a computer, and then you’ll feed them through a cable into
the PICAXE memory. So you’ll need to buy a cable, and you’ll need software to
help you to write the program.
Figure 5-122. A page from the PICAXE cata-
log lists only some of the chips that are
available. What began as an educational
aid has become a useful prototyping tool.