tools. Often it’s equipment the average customer would
not typically be using, but the kind of stuff other
developers might be.
I’m often asked by customers, “What tools do you
use? What do you recommend?” I’d like to answer this
question by exploring the tools I feel are important on
any bench whether you work with electronics and/or
microcontrollers as an experimenter, hobbyist, technician,
or engineer. Let’s start with test tools.
Digital Multimeters
The most basic test tool you should have is a digital
multimeter (DMM). I can’t overstate how important this
tool is. There are so many times an issue is related to
something simple like low voltage, current issues, a broken
trace/wire, or something else that can be easily detected
with a DMM. A basic unit can help you obtain voltage
and resistance, and can be found for around $10 from
many retail sources. Of course, if you prefer more quality,
features, and safety, you’ll want to invest in a more decent
unit, especially if you use it as often as I do — which is
almost every day. I prefer Fluke digital
multimeters as do most of my colleagues
and peers. Fluke units are high quality
dependable tools that offer high accuracy
and robust features.
Figure 2 shows my favorite Fluke DMM
models and the ones I use for personal and
work projects. Both models offer quality
and features not available in cheap
multimeters, and a level of reliability and
consistency that makes the choice easy for me. In
addition to measuring AC/DC voltage/current, resistance,
continuity, capacitance, and temperature, they also have a
diode checker, analog bar display, and a host of other
features. Be sure to go to the Fluke website for more
information.
Logic Analyzers
A logic analyzer is a must-have for the type of work I
do. This device can capture digital signals, allowing you to
easily detect missing signals or improper timing. I use a
logic analyzer for timing and communication issues.
Most logic analyzers have protocol decoders which
allow you to see the communication on various types of
busses such as SPI, I2C, asynchronous serial, and more. If
you work with these signals and have a need to see what
is being sent on various busses, then a logic analyzer is
truly valuable.
My logic analyzer of choice is the Saleae Logic
(Figure 3). I have been using the 16- and eight-channel
models for several years. Saleae is in the process of
releasing some newer logic analyzers which also support
analog, however, the new hardware was not available for
this article.
Unlike most of my other test equipment, the Saleae
Logic does require a PC and is a USB device.
Oscilloscopes
A good oscilloscope is an important piece of
equipment and — for some reason — was the hardest tool
for me to acquire when I first got started. Scopes were
expensive in the ’80s and ’90s, and I just didn’t have the
funds to purchase one. Older Tektronix analog scopes
were how I got started. The first scope I ever owned was a
Heathkit scope that was partially assembled and that I
picked up in the late ’90s. Later, I was able to acquire a
more modern Tektronix two-channel digital oscilloscope.
When I started working at Parallax, most of the scopes
were Tektronix digital units; some had storage capability
and other features.
An oscilloscope can help you see things that a DMM
and a logic analyzer cannot. A DMM is typically too slow
to show rapid changes in voltages or currents, and
therefore cannot see noise, dips, or spikes. A logic
analyzer only shows logic ones and zeros, so voltages that
are outside of the logic threshold are often invisible to this
device. A scope can see a signal in real time, showing a
graphical representation of the signal on the screen.
The scope is looking at a relatively narrow period of time.
By expanding that to be more visible, you can see the
details of the signal such as rise/fall time, level, noise, and
other properties.
November 2014 47
FIGURE 3.
FIGURE 2.
