As much as I lost my heart to -- and built my first Arduino project on -- Adafruit's Trinket, the game-changer (for me) was stumbling across the chip-on-board form-factor. That form-factor is not unique to the Arduino universe, where it's sometimes called "Boarduino." We'll get to that in a later post. For now, however, I want to focus on the mechanics of the breadboard itself. Because [extremely schmoozy voice] that's where the magic happens [/extremely schmoozy voice]
First things first: What is it good for? "Prototyping" is the obvious answer. But, chez fivechimera, there's also a long -- and sometimes even honourable -- history of prototypes being "good enough" for literal years of full-time use. Until they're not and the parts go back into their Cabela's tackle-boxes for next time.
This is not a novel concept: "Breadboarding" gets its name from the days of yore -- by which I mean literally a hundred years ago -- when you wired up your project by literally pounding nails into a breadboard (or any wide slab of wood), and winding copper wire around them to create a circuit. Homebrew ("cat's whisker") radios were a Very Big Deal. (See also: https://www.mikeselectronicparts.com/wp-content/uploads/building-a-crystal-radio.pdf)
But, doubtless, one big selling point in those pre-Radio Shack days, was that once that project's usefulness ended, one could always pry loose the widgets, un-string the wire for later use (copper is expensive, y'all!), and pull the nails from the breadboard to restore it to its blank-canvas state.
And so reusability is the main reason I prefer the Boarduino form-factor. Assuming that you're working w/in certain constraints, reducing project footprint is the second-best reason. Assuming, of course, that the project can live inside certain limitations:
- Current limitations: Each small hole (a.k.a. "tie point," a.k.a. "pin") on a solderless breadboard should never carry more than 500mA, or 1/2 of an Amp. of current through it. Theoretically, they can take up to one Amp. Just don't. Most especially projects that will be up and running for awhile. It's not worth the risk.
- Voltage limitations: Stick to 5 volts DC. Again, you want to stay well within the safety zone.
- Pin spacing: If the widgets you're planning to plug into your breadboard don't have pins 2.5mm (or 0.1 inch) apart, you're going to need to make other wiring arrangements. We'll get to those options in a subsequent post.
- "Stupid-proofing": Nothing in a breadboard's construction limits current polarity. By which I mean, if you mix up positive and ground, the breadboard will not step in to save you. At best, your project just won't work. A short can melt the breadboard plastic. (Ask me how I know.) You also risk frying any widget connected to the faulty wiring -- up to and including the microcontroller.
- Layout limitations: Do you have enough room on the breadboard for the microcontroller chip (a.k.a. MCU) and all your widgets? If not, how are you going to work around that when your project is up and running in the real world?
Which brings me to breadboard sizes and their features (or lack thereof). There might be a few exotic outliers, but here's the range I've stumbled over through the last few years:
I would say that they come in all shapes and sizes, except that the shape is limited to rectangular.
Half-size (top left): In my experience, this is usually the optimal size for a Boarduino projects. The holes ("pins") come in two flavours.
- The two rows that run (horizontally) along the long edges of each side are often referred to as "power rails." Traditionally, red is connected to the positive end of the power source and runs, uninterrupted from one end to the other. Ground is wired into blue. By default, the power rails on each side are independent of each other.
- If we consider the power rails to be "rows," then the other flavour of pins can be considered "columns." These run perpendicular to the rails. The five pins of each column -- highlighted in neon green -- are connected to each other. They are not, however, connected to the column on the other side of the trench that runs between them.
Full size (right): Similar to the half-size with more "tie points" and often more flexibility. Depending on the manufacturer, you might need to bridge the two halves of the power-rails. Or not, depending on your project layout.
Mini (middle left): In this case, there are no power-rails "rows"; only "columns" of five interconnected pins. You will have to use one column for a positive rail and one for the negative. Which brings one big no-no: Never, EVER wire positive and negative into the same column. Even for the simplest project.
Micro (bottom left, shown top and bottom): For grins, I'm throwing this one in. And, no, I have no idea what's going on with those "Lego-bumps" on the underside except to guess that they allow the breadboard to be glued/screwed into place from the underside of some project??? Again, I have no idea.
Now. All of the above assumes that you have some basic understanding of how circuits work. If you're still new to the concepts and/or hesitant to play with live electricity, you can "practice" your wiring skills virtually.
Most electronics prototyping/visualisation software is geared for PCBs -- printed circuit boards. That's both an intermediate/advanced move as well as one more or less alien to this feature's "Boarduino" focus. If you're serious about electronics design, you will need to learn how to "think" in PCB. For now, don't worry about it. In practice, that leaves two non-trivial options:
TinkerCad is "free" in the sense that you can give AutoDesk your email address -- be sure to use the "spam" one -- and play around in the "Electronics" section to see what I mean.
- Pros: It's "free" in the sense that you're giving a large company your email address and the user interface is quite intuitive. Also, it's online, so no PC-vs.-Mac-vs.-Linux issues to worry about
- Cons: AutoDesk offers shockingly small range of "widgets" to plug into the breadboard.
Fritzing is payware. (Normally, I'm more than happy to trade money-for-value...until that money is processed by [spits] Paypal.)
- Pros: A much, much broader variety of widgets. Some vendors (wisely) contribute to the Fritzing project; others don't. But you can normally find something "close enough."
- Cons: A slightly steeper -- if unsurprising -- learning-curve because there are more features. (Pro tip: Save yourself a bunch of grief and learn how to "lock" main widgets like the breadboard in place. Otherwise, it's far, far too reminiscent of the mayhem of resizing and image in Microsoft Word.)
Of the two, I personally prefer the features-vs.-complexity balance of Fritzing. If you're not sure that you're going to stick with this hobby (or don't have access to a payment method that [spits] Paypal will accept), TinkerCad should be more than enough to get a feel for breadboard circuitry.
That' about all I have for this installment. An excellent deep-dive into the construction of breadboards can be found here: https://protosupplies.com/guide-to-solderless-breadboards.
Next time, I'm planning on going through the often-overlooked mechanics of creating circuits, with, of course, a particular emphasis on breadboards.
Until then, Tchein ton siault d'beluets!
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Credit where it's due: Dennis Freeberg, for the square-on photo of the half-size breadboard.
