I love the Arduino Nano. It has all the thinkin' power of a full-size Arduino, but in a teeny-tiny package. On-board USB, volt reg, indicator LED's, even a reset button and all the size of a stick of gum. Alas, with all this greatness comes the fact that it is a royal pain to actually connect anything to it. 

                                                      The Rocket Brand Nano UnderShields to the Rescue.
                                                                                   Rocket Brand Studios

The Nano UnderSheilds are perfect for small robot projects with everything you need and nothing you don't. Power for motors and data is separate allowing for testing without the robot driving off the desk. Power going to the servos, sensors and other doo-dads can come from the Nano's on-board volt reg or from an external 5v source. The L293D motor driver will handle most small drive motors and is wired for full PWM speed control including electronic braking! It's just gosh-darn-good.

The UnderShield Kits are not only great as a stand-along start of a great project but are also included standard in the:

The UnderShield Classic, at just over 1"x2" has connections for:
  • 2 Servos or other digital devices
  • 2 Analog inputs
  • 1 Ping))) sensor or other digital device
  • Separate data and motor power inputs
  • 2 motors with on-board L293D motor driver 
  • In addition to the connections above, all the pins of the Arduino Nano can be accessed through female headers
The UnderShield with Pins (just slightly wider than the classic) has:
  • All I/O pins broken out to female headers
  • All I/O pins broken out to 3-pin male headers
  • Separate data and motor power inputs
  • 2 motors with on-board L293D motor driver

Step 1: Assembly Intro

Lets get started. This is a pretty darn simply kit and it is really nothing more than the grunt-work of soldering the many pins. You will need:
  • Soldering Iron
  • Flux core solder
  • Dykes (Diagonal Cutters, Nippers, Nippies, Wire Cutters)
  • Maybe a bit of masking tape
  • One of those "helping hands" things is pretty handy too
Now, if you have not soldered before, have no fear. The amazing tubes of the internets contain about 1.6 trillion soldering videos so I am not going to get into how to solder here. --Hit the YouTube and hit the Google and find a tutorial you like. I will say this though, for cryin' out loud, use a wet sponge to clean your soldering iron tip! Clean it well and often. Wipe, then re-tin with a wee bit of solder on the tip. You are soldering a circuit board, not a pipe under your sink!

Step 2: Assembly 1

Let's start with the motor driver socket and, if you are putting together the UnderShield Classis, the resistors. Start with the I.C. socket (not the chip itself) and stick it in. Note the fact that it has a wee notch at one end and that notch should match the notch in the printed outline where it goes. Also, be sure it covers "L293D" and NOT "v2" or "v1-P" --Don't put it on the back!

A little masking tape can hold it down while you work. I personally like to solder just 2 pins, then stop and check that it is sitting flat and flush to the board before I solder all the pins down. When you are happy with the fit and placement, solder all the pins.

If you are doing the Classic, you can also install the (2) resistors. They go where "4.7k" is printed and they can go either way (you can't put them in backward). Tape them down or bend their legs outward slightly to hold them. Solder those bad-boys in. Clippy-clip off the extra leg hanging down.

**Do not plug in the motor driver chip yet.

Step 3: Assembly 2

Female Headers

We are going to solder in the female headers now. If for some reason, you have a older version of the kit you may have received a few strips of female headers. You will need to cut these into the lengths you need. You will need a total of (4) strips 15-pins long. Note that when you cut these, you will cut ON a hole. I.e. You are going to "loose" one of the holes during the cutting process. Hit the ends with an X-acto knife or a little sandpaper if you want it to look sorta pretty.

In the more recent kits, I am including 2x15 headers which will not need to be cut. 

In either case, these female headers sorta go "the only place they can" along either side of the motor driver socket. If you are putting together the UnderShield with Pins, be sure you put them as close to the center of the board you can. I.e. be sure after they are in, you still have 3 holes showing between the female headers and the outside edges of the board.

Tape them down or simply invert the board on your desk. In either case, be VERY sure they are flat to the board, flush and 90 degrees to the board. If they are not darn-close to 90 degrees, it will be a pain to plug in the Nano later. Solder just a couple pins, remove the tape (if you used it) and double check for straight. Fudge-a-ludge them around until they are straight then solder all the pins.

Step 4: Assembly 3

Gotta lotta pins.

Let's start with breaking the strips of pins into the sizes you need. 

The Classic will need:
  • (2) sets of 2-pins
  • (3) sets of 5-pins --or-- (5) sets of 3-pins (I think the 5-pin-long is the way to go here and is easier to solder)
  • (2) 2x2-pin bent headers (these are probably already broken apart for you)
The UnderSheild with Pins will need:
  • (2) sets of 2-pins
  • (4) sets of 3-pins
  • (6) sets of 11-pins
  • (2) 2x2-pin bent headers (these are probably already broken apart for you)
At this point, I will direct you to look at the pictures attached to this step. It is far easier for you to simply "make it look like the picture" than trying to describe it here. I can also say that there is simply no good way of holding these darn things when soldering. You gotta figure it out and get creative --do whatcha gotta do to get em' straight, flat, flush and 90 degrees to the board. Stick em' in and solder them down.

Note: It is easy to put the bent pins in wrong. The straight part will stick out past the edge of the board. The bent part goes ON the board. Again --look at the pictures, yo.

Step 5: Assembly 4

You wicked close to being done!

We gotta stick the chip in now but you will find if you do that the legs are a little wide. --All chips are like this. Now, we need to bend them in a little but trust me, this can go really bad --really fast. DO NOT try to bend these by hand. Instead, place the chip against your desk and bend all the legs at once. Go slow, support the chip and just bend them a little bit. Check it and bend a bit more if needed. Patience here, Skippy --Don't fudge it up here.

When it looks like the legs are narrow enough to fit, go ahead and plug it in MAKING SURE the notch at the top of the chip matches the notch in the socket which matches the notch in the outline printed on the board.

Lastly, go ahead and plug the tiny jumper block. It goes on the (2) pins in the set of four. --These pins are the one's closest to the "R" in "Rocket Brand" printed on the board. It should bridge the (2) pins closest to the center of the board. The (2) pins left, labeled "+" and "-" should be left uncovered. <--This is wicked important. DO NOT connect the (2) "+ and -" pins with the jumper!

There is more about this jumper in the next step as well as the instruction manual.

Check your work!!! Before you do anything else, check your work. If any of your solder joints look ugly, dry, not fully covered or worse yet, there is a "bridge" of solder connecting two pins, FIX IT! You cannot omit this step. Grab a magnifier if you have to, take your time and really look over it well. This could be the difference between working and a puff of stinky smoke. Check yourself before you wreck yourself, yo.

That's it. You did it. Go ahead and plug in your Arduino Nano. The USB goes to the end of the board with the bent pins.

Step 6: Quick Run-Down on Use

Everything is pretty straight-forward here, the only real issue is with power going into this guy. There are a couple ways to give this guy some juice and one way to NOT do it. I will give you the quick run down here but PLEASE take a quick second to go over the instruction manual. It shows all this in greater detail, has a list of all the pins used and more. For cryin' out loud, RTFM and don't smoke your chip due to a simple mistake.

First off, motor power. The power for the motors goes into "Motors in" or "Mot. In" printed on the underside of the board. Ground is closest to the edge of the board and thus, is the "lower" pin. Positive is closest to the center of the board and thus, becomes the "top" pin. If you want your motors to go, plug power in here. Total voltage should not exceed the ability of the L293D or your particular motors. The datasheet for the L293D is in the instruction manual and the specs on your motors can be found from wherever you bought them. In general, with the kind of motors one would probably connect to this board, you are probably looking at 5-9 volts or so but man, double check yourself here.

We move on to data power. The Arduino Nano board has an on-board regulator to knock-down a high input voltage down to the 5v that the chip needs. I have read that the actual range is 7 to 12 volts but in practice, it is probably closer to 5.8v as a minimum (before the volt reg craps out) and I would say that 12v is really pushing it. At 12v the volt reg is literally "burning" off 7 of those 12 volts in the form of heat. It is inefficient and  really hard on the volt reg. It has been my experience that these Nano's (and the undershield) work awesome with either a (6) AA pack, a 7.2v "racing pack" or a small, 2-cell 7.4v lipo. This 7-point-something range seems to run 6v motors just fine and is right in the meat of the range of voltages the regulator will play nice with. Consult the Arduino website for more information about the Nano and it's power requirements.

Now, if you go this route --with a 6-9v supply (or so) you will connect to the "data pwr in" connection right next to the "motors in" connection. DO NOT connect any power to the (2) pins near the jumper block!!! 

Another power option is for folks using (3) alkaline batteries or (4) rechargeable batteries. These packs will give out around 4.5v or so (maybe as high as 5.2v when new or fully charged). The Arduino is quite happy running at 4.5 volts, or even as low as 4v but you can't (and don't need to) use the voltage regulator. In this case, you will connect your battery pack to the (2) pins next to the jumper block. In this configuration, you are "bypassing" the onboard regulator and powering the Arduino directly --Do not exceed 5v here, dude. Be sure you have the polarity correct and that you are connection to the (2) pins closest to the edge of the board --the one's with "+" and "-" printed next to them. DO NOT connect any power to the "Data pwr in" pins near the "Motor in" pins when doing this. Also, DO NOT allow any voltages above 5.2v (maybe 5.3v AT MOST) on these pins.

Ah yes, the jumper block...

(If you check out the instruction manual, there are pictures of all this.)

Put simply, the jumper block connects the 5V "system" going to or from the Nano to the "servo" and "sensor" pins of the Classic or to the center pin (positive pin) of all the 3-pin headers of the Undershield with Pins. Here are a few configurations:
  • A 7.2 volt supply plugged into the "Data pwr in" pins near the "motor pwr in" pins. If the jumper is installed here, the 5v from the Nano's regulator goes to the servo and sensor pins or all the 3-pin connections. Be careful not to try to suck too much current from the regulator doing this. --If you are just running a servo or 2 and a couple sensors, you are probably good to go. If you are running 12 servos in a hexapod, you will smoke your volt reg doing this. Also, the (2) pins next to the jumper will give you 5V going OUT in this configuration.
  • A 7.2 supply plugged in as described above but with the jumper removed. This will power your Nano via the regulator. However, the output of the regulator is NOT connected to the servo and sensor pins nor to any of the 3-pin headers. To power these pins an external 5v supply can be used and should be connected to the 2 pins next to where the jumper used to be. This is the only time you can have power going to both the end and side pwr-in connections. If you power both connections with the jumper installed, bad things happen.
  • A 4.5v pack connected to the pins closest to the jumper block and the jumper installed. In this position, the 4.5v bypasses the voltage regulator, powers the Arduino directly and will also supply the servo and sensor pins or all the 3-pin connections. This will probably be the most common set up.
**The bottom line here is that you should NEVER have both "Pwr in" connections receiving power with the jumper installed!! Well, you can, but you can only do it once.
Thanks, very helpful.(seriously!)

About This Instructable




More by Chris the Carpenter:Rocket Brand Studios Tiny Tank Rocket Brand Studios Medium Tank The Glen the Stove Project 
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