time clock, an LCD and buttons, and a host of other
components. By using a microcontroller, I was able to
design and build the whole project on a single printed
circuit board (PCB). If I’d gone with an Uno, I would have
needed to find a way to mount the Arduino onto my
board — or worse, connect it with a whole lot of wires just
waiting to come loose.
Cost: There are some low cost Arduino clones
available, but they’ll be hard-pressed to beat the cost of a
microcontroller integrated into your own PCB. The
Arduino is great as a prototyping and learning platform,
but it just doesn’t make sense to have one of these built
into every one of your working projects.
Best Tool for the Job: The Arduino range has only a
handful of microcontrollers to choose from — and for
good reason. However, when I started on one of my
smaller sensor projects, having a 28-pin MCU was
complete overkill. Instead I opted for a smaller Atmel
MCU: an eight-pin ATtiny85.
Additional Flexibility: I recently created a small
sensor that I wanted to run on a single battery for at least
a year. The design needed to incorporate a slower watch
crystal, running at 32. 7 kHz. This crystal runs more than
480 times slower than the standard 16 MHz Uno, which
translates into a real power savings. I needed flexibility
that the Arduino (with a built-in crystal) couldn’t offer me.
38 March 2015
Schematic of the