Servo - August 2008

Moving From BS1 to PIC

by William Smith

A high school teacher recently sent me an email asking for advice on the best path to move from the BASIC Stamp 1 (BS1) module to Microchip PICs. He had his students programming the BS1 Project Board (Figure 1) which is a very nice board for the price. He was happy with that board as an entry point, but the next step in the BASIC Stamp world was moving to the BS2 Homework Board, which is a $45 development board. He hoped to keep it below $25. He thought maybe programming a PIC microcontroller directly might be the best option since the BS1 is based on that same family of microcontroller ...

With all the various programmers, tools, and compiler options though, he was getting confused. He wanted to be able to program blank PICs, not another company’s chip where you have to buy from a limited number of sources. This ruled out the Basic Atom, the PICAXE, and a few others. What I hope to show you in this article is the same thing we emonstrated to the high school. You can put together a great starter package for under $25 using mostly free samples and free downloads from the Internet.

Requirements

The BS1 has an 80 command limit, but the high school teacher stated that many of the projects his students worked on were very simple and didn’t require a lot of code space. On the other hand, he wanted an upgrade path to offer more space and definitely more speed to his advanced students. He also wanted to be able to access the PIC’s built-in features

such as A/D and timers. As a simple
test, he asked if we could recommend
a package and offer a simple example
for driving an LCD module as a basic
demonstration. This took many lines
of code in the BS1, so he either needed
to use an expensive serial LCD module
or move up to a larger part like the
BS2 to do more with it. He stated that
he’d seen sample code with a single
LCD control command that simplified
driving an LCD and wondered if the
PIC had that option built in. That was
the challenge he placed before me.
Based on these requirements, I
told him that we could show him
an LCD example with very little
effort, using a BASIC compiler
that will easily convert over his
existing code and offer an easy
upgrade path to full professional
PIC programming for his
students down the road. He
was very interested so he wanted
more detail.