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All the concepts you learn with
any MCU system will be able to be
applied to any other system. The
syntax and instructions will vary but
the concepts remain the same.
Arduino has a number of books
written about it and is probably the
most popular among those who know
little about MCUs. It was made with
artists and builders in mind, not for
engineers and tech-like people. They
have done a good job of marketing
and there are many applications made
accessible through their "shield"
format. Of course, there are quite a
few books written about Arduino and
you should examine whichever book
to find out what parts you will need to
work with the projects.
The PICAXE is also fairly popular
and is programmed in a version of
Basic. The Propeller is supposed to be
a little more advanced as are AVRs,
PICs, and other major companies'
MCUs that are mostly programmed in
C. For a beginner, I would stay away
from the Propeller, AVRs, and PICs as
there will probably be too steep a
learning curve. The BASIC Stamp 2 is
a little more expensive as you will
need the MCU and, if it is not a USB
version, you will also need a USB to
RS-232 converter — unless you have a
PC with the old serial port, DB9 style.
The Arduino is cheaper and more
popular, but you will most likely have
to do a little more searching and trial
and error to get your code running
with the documentation available.
Parallax (the company that makes the
BS2) has very good documentation.
Another advantage of the Arduino is
that programs written in C/C++ will
also work in the Arduino environment.
Books for the BS2: What's a
Microcontroller? and Stamp Works."
Books for Arduino: the Evil
Genius books and probably Arduino
Books for the PICAXE: Unknown
but there are bound to be some on
the PICAXE homepage, as well as
#2 I’m also at a similar beginning
stage, as you describe. I am currently
working through a book called
C Programming for Embedded
Microcontrollers by Warwick A. Smith,
which I find thus far to be excellent.
The ISBN is 978-0-905705-80-4.
Here are the books, features, and
Use only free or open source
Learn how to download, set up,
and use free C programming tools.
Start learning the C language to
write simple PC programs before
tackling embedded programming —
No need to buy an embedded system
Start learning to program from
the very first chapter with simple
programs and slowly build from
there. No programming experience is
Learn by doing — Type and run the
example programs and exercises
which can be downloaded from the
Internet. — A fun way to learn the
C programming language.
Ideal for electronic hobbyists,
students and engineers wanting to
learn the C programming language in
an embedded environment on ARM
As a beginner, I personally found
Arduino to be the easiest platform to
get a running start.
[#2132 - Februsry 2013]
Inductive Kick Diode
I built a PWM controller for a
36 volt golf cart motor. What size,
amperage, and voltage do I need for
the motor's fly-back diode?
The maximum reverse voltage
across the diode will be 36 volts. A
conservative rule of thumb is to
double that, so choose a diode with a
rating of at least 72 volts. The maximum current will be whatever your
PWM controller delivers to the motor.
When the PWM controller shuts off at
the end of each cycle, the voltage
across the motor inductance will
instantaneously reverse polarity and
begin to flow through the diode.
Using the same rule of thumb, pick a
diode that is rated for twice this
current. You also need to be sure the
diode can dissipate the power while
keeping its junction temperature
below TJ max (150 deg C is typical).
The power dissipated is 1/2 L I^ 2
(the energy stored in the motor inductance) multiplied by the frequency of
your PWM controller. Depending on
this result, you may need to put the
diode on a heatsink.