An Arduino Board For Your Tiniest Of Projects


Instructables user [dustinandrews] just took the wraps off his latest creation, a DIY Arduino Pro Mini clone.

Actually, to call it an clone is technically incorrect – while he aimed to produce a tiny Arduino-compatible board, his goal was not to replicate the Mini’s design. Instead, he developed a 1” x 1” board from scratch, covering the construction process in great detail.

When you are working with components this tiny, the only reasonable way to get things done is via solder reflow. He walks through the steps he took to produce the board, which should be enough to guide those doing reflow for the first time through the process without too much trouble.

The end result looks pretty nice, and when he puts it up side by side against the Arduino Pro Mini, his board can definitely hold its own. While his design lacks an on-board power regulator and reset button, he does provide two more analog I/O pins than the Mini, along with several other enhancements.

29 thoughts on “An Arduino Board For Your Tiniest Of Projects

    1. @Ad, you are reading the caliper incorrectly. The “IN” and “OUT” marks on the frame are where dimensions are read. It is about 22 mm or exactly 7/8″. Or 0.875″ if you have difficulty with practical dimensions.

      @mad_max, don’t be ignorant, please.

      1. You are right.

        One of the annotated images in the instructable lists it at 1″ x 1 1/8″.

        To clarify the perceived “surface mount hate” people are claiming, there’s no smd hate here. I have done my fair share of smd soldering, and it’s not bad if you have a steady hand and can drag with skill. The “only reasonable way” was more of an off-the-cuff/artistic licence/making conversation type of statement.

        Really, the only “reasonable way” to do surface mount work is whichever way fits your skill set.

  1. Wusses, I solder 0201 no scope by hand.

    I’m always amazed how little it takes to get a uC running these days, power + a couple of passives and you’re good to go.

      1. “I should say that I have inhaled a few 0201 in my time. Can’t be healthy.”
        Unhealthy!? Inhale the wrong components and you could end up incapacitated!

        Yes, yes a terrible pun I know…

  2. the instructables’ author is to be commended for helping to encourage folks, and the design. but hackaday saying that reflow is the only reasonable way to do this kind of thing accomplishes exactly the opposite, and makes dealing with surface mount sound harder than it is.

    1. +1,
      Its shocking how bad the attitude towards surface mount is and ThruHole is the only way for hobbyist. IMO surface mount is easier as you don’t have to worry about connectivity through vias, or have tracking on opposite side to components.
      Saying that, surface mount is a load easier when you’ve got the right solder tip – I’ve found the bucket type tip to be the best. I much prefer that to pointy ones or even chisel tips.

      I’m a firm believer in tack and drag…although I tend to drag away from the pins instead of across them

      1. Through hole components have their pros as well. First of all, it’s much easier to reuse an IC that is socketed than it is to reuse one that has been soldered on the board. This is really important when prototyping and doing different PCB revisions.

        Moreover, you can fit a few tracks under a through hole resistor. There is not enogh space for anything between pads of a 0603 resistor.

        Both packaging types have their uses. In hobby projects there is usually no need to aim for minimal circuit size.

    1. Yes. The Arduino crowd likes renaming stuff.

      For example, they decided to call programming “sketching with hardware” instead. Between that and them renaming C++ to “Wiring”, for the longest time I thought Arduinos were programmed using some interface where you drag and drop functional blocks from a library as graphic elements on-screen, then connect them with “wires” to define relationships. I have seen systems like that before, and they’re incredibly limited; so I looked no further into the Arduinos. And that’s why I *used* to dislike both the Arduino and the intense interest in them.

      Of course, eventually I found this wasn’t correct. You program an Arduino in C just like any other MCU, despite the “sketchy” names.

      So *now* I dislike Arduino because there’s no reason for the needless renaming other than to be separatist or elitist, or maybe to confuse newcomers into thinking the Arduino is more unique than it really is. (It’s by no means the only dev system with a bootloader and peripheral library.)

      Glad to see there are people who still see things for what they really are. This is a good ATMega board, not necessarily an Arduino. And a great Instructable.

      1. “Programming” is a scary word to people who haven’t programmed before. They were just trying to make the platform appear friendlier to people with no experience of programming.

      2. When trolling you should probably take a few minutes to get your facts straight. From the home page:

        “Arduino can sense the environment by receiving input from a variety of sensors and can affect its surroundings by controlling lights, motors, and other actuators. The microcontroller on the board is programmed using the Arduino programming language (based on Wiring) and the Arduino development environment (based on Processing). Arduino projects can be stand-alone or they can communicate with software running on a computer (e.g. Flash, Processing, MaxMSP).”

        If you search for the word ‘sketch’ you will not find it anywhere on that page.

        From the FAQ page:

        Q: Can I program the Arduino board in C?
        A: In fact, you already are; the Arduino language is merely a set of C/C++ functions that can be called from your code. Your sketch undergoes minor changes (e.g. automatic generation of function prototypes) and then is passed directly to a C/C++ compiler (avr-g++). All standard C and C++ constructs supported by avr-g++ should work in Arduino. For more details, see the page on the Arduino build process.

        This is the only location where the word ‘sketch’ exists in the FAQ. Hardly the behaviour you would expect from an organisation that has “decided to call programming “sketching with hardware” ”

        “Glad to see there are people who still see things for what they really are. This is a good ATMega board, not necessarily an Arduino. And a great Instructable.”

        The guy in the instructable says arduino about 2 dozen times. Simply calling it an ATMega board is like saying your stack of intel components with OSX on it is simply a ‘computer’ and not a ‘mac’

    2. @Pedro, I’d think that anyone so easily scared away by a simple term like “programming”, would soon be scared away anyway by any of the challenges encountered while actually doing it; regardless of what it’s called.

      But maybe you’re right. And we should give other things friendly names too. I’ll start.

      From this day forward, everyone should refer to “soldering” as “gluing with metal”.

      1. How about “Circuit Brazing”?

        “Hey there artsy guy, amazing circuit brazing!”

        Honestly, I like to look past the oddities of certain things and focus on the meat. If the meat is good… then you can call it whatever you want, I’m eating it up.

        Try not to get distracted by the little things…

        Also, I commend the Arduino team for coming up with something different that stands out. It caught on and the rest is history.

        I’m an Arduino user… and a PIC user, and an Atmel user, among many more.

  3. Hmmm… I am pretty sure you could shrink it further by using 2mm headers! That might put you on the spot to make a 2mm solderless breadboard, though. My next project! :-) First, I’ll need a RepRap. Or a shrink-ray. :-(

  4. I had no trouble soldering my tiny328 pcb by hand.

    I used a flow-tip (aka bucket/spoon). But it is quite easy to solder the micro using standard tips.
    I’ve found 3mm bevels and knife tips particular good for SMD. Re-work flux is essential.
    I do concede the reliability is not perfect and I have to check the boards with a magnifier and redo a joint or two.

  5. Guys, soldering 0201 by hand is no problem as long as your vision is OK. I can’t do it with my contacts in, so I have to wear glasses when I am doing 0201/0401 soldering, I take the glasses off which allows me to see things much better when they are close to my eyes. Safety glasses are a must, and for the >0603 components I always recommend inspecting with a magnifier when you are done. I can populated a small board with ~100 0603 and smaller passives and TSSOP/SOT IC’s in about 20 minutes. Practice makes perfect! SMD has made my prototyping infinitely easier. I was so happy to say goodbye to thru-hole :)

    Now, the only drilling I do is for vias!

    For those of you who are afraid of SMD or think it is harder than thru-hole, you are so wrong! It is faster, cleaner, and more compact. There are virtually no disadvantages to SMD unless you are blind and only have thumbs.

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