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Build Notes

GET READY

Before you begin, inspect the boards carefully to make sure there are no manufacturing defects that affect the traces or through-holes. It's a complicated design and occasional manufacturing glitches can happen. If you overlook something, or make a mistake soldering, keep in mind that the stribe's a fairly simple circuit - the complexity is in the high quanity of parts and their density on the board. Most glitches can be wired-around by hand if needed.

Tools you'll probably need: An adjustable temperature soldering station, I like to use a small soldering tip. You'll need a small assortment of decent snips, pliers and tweezers, solder, a solder-sucker, some solid core hobby wire just in case, and the occasional needle or dental tool will come in handy. In general when buying this stuff quality beats quantity every time. You'll use a really nice pair of snips all the time, while the cheap set will break immediately or languish in the closet.

You'll also need a file or sandpaper to whittle down the female headers for the LED board assembly. I use an old metal file from the shed - I think any file will do, like even a nail file should work, or sand paper and a block.



Most of all, be relaxed and don't try to do too much of the kit at once. Play some nice music and settle in. Too much caffeine leads to shaky hands, as does being tired. I know I get impatient and sloppy when I'm tired or stressed-out. Do a bit at a time and enjoy the process. There are a lot of rather expensive parts in this kit, so it would be a waste for it not to work right because you rushed it.

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Feel free to contact me with questions or post here before you do something rash.

Parts List

1 stribe driver circuit board
1 stribe led circuit board
8 170mm touch strips
1 7" x 7 1/8" x 1/8" (or 1/16") plexiglas/perspex sheet
1 6mm push-button mini-switch
1 Arduino MINI 04 "Stamp" (microcontroller)
1 Arduino USB "Stamp" (USB connectivity)
4 rubber stick-on feet
112 10-segment LED bargraphs
112 20-position .300" IC sockets
16 MAXIM MAX7221 led driver ICs
16 24-position .300" IC sockets
16 47k resistors
9 9.53k resistors
16 .1uf ceramic disc capacitors
16 10uf electrolytic capacitors, (short body: 5mm x 5mm)
12 .10 40 pin male square pin header - single row
18* .10 16 pin female header - single row
4 .10 8 pin female header - single row
2 .10 10 pin female header - single row
1 .10 4-pin female header - dual row (2x2)
1 .10 2-position male header - dual row (2x2)

* minor change: instead of 2 12-position female headers, I tossed in 2 extra 16-pin headers. Cut these to length with some sturdy wire-cutters. When you cut a female header, you always lose a position, so cut right in the middle of the un-needed position adjacent to the last pin. File it down later to look nice.

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This gives you the guts. You will have to build your own case.

Description

The stribe prototype consists of 8 layers of parts sandwiched together into a single slab.



note: before the touchstrips are adhered to the plexi surface, tape it in place to keep it from moving around. I suggest testing the LEDs without the plexi, THEN use thin strips of transparent, long-lasting packing tape to hold it in place - it makes for a nicer finished product than this scotch tape. The scotch tape, however, allows you to easily remove it to shuffle the LED bargraphs around. After repeated on and off it will get a little gunky - use alchohol and a cotton swab to clean it off. The flexible sheet approach will become translucent after a while but still works. It's a matter of taste and the durability of the softpot material will prove itself over time. Another option is to adhere them to a sheet that is already sort of translucent like the tape. Translucent is kinda sexy-looking and it works, I just prefer the transparent cause I'm a geek.

From the top down:

1) 8 adhesive-backed 170 mm touch-strip sensors

2) a thin sheet of transparent or translucent plastic, to which the sensors adhere

3) 112 10-segment LED bar-graph arrays

4) 112 IC sockets, which hold the bar-graph arrays

5) a 2-sided LED circuit board, which routes the LED connections to the edge

6) a female header that runs all around the edge of the LED board

7) a matching male header that runs around the edge of the DRIVER board

8) a 4-sided DRIVER circuit board, which serves several purposes:

a. it holds the 16 MAX7221's and supporting circuitry
b. provides sockets for the Arduino MINI uC and Arduino USB stamp
c. provides (8) 3-pin connectors for the sensors

9) 4 rubber feet stick to the bottom of the circuit board. A hole at each corner of the circuit board allows it to be screwed to a piece of wood for a more solid base, or it can be bolted from underneath into a cover plate to hold everything tightly together and prevent shifting, perhaps a bevel to hold the LED/perspex sheet combo.

First: Build the LED board

1) Solder 112 IC sockets to the LED board

a. Look for a marking on the LED board, on the edge: (top)
Orient the board accordingly

b. Prop the circuit board up on something so the legs of the sockets will hang free (I use a roll of duck tape on it's side), then load a column of 7 sockets down each edge of the board (start with the far left and the far right column - just do it this way, trust me). It's not required but I like to orient the notch in the sockets towards the top. Make sure there is a row of holes at the top and bottom of each column left open for the header that will be soldered in later! And make sure there is a similar row of open holes next to the sockets. Be careful not to accidentally glop solder in these holes.



c. Place a precut length of duck tape over the sockets to hold them in place. You'll mess this up a couple of times and accidentally pull half of them out trying to adjust it and have to start over - but you'll eventually get the hang of it.



d. Run a thumbnail or coin along the duct tape to push it into the grooves of the sockets, and make sure they stay aligned with each other, that none of them are rocked to the left or right. I do the two sides at the same time (left and right) so that when I flip it over the first time, it is balanced and stays flat against the work surface. Now the sockets won't move or tilt while I'm soldering.



e. Solder each socket leg of both rows into place. Keep the iron hot and your tip clean and try to get into a rhythm. Keep a solder-sucker handy for when you glob things up. I use a magnifying lamp for this but you might have younger eyes than me. In any case, it never hurts to examine the solder joints afterwards with a magnifying glass to make sure there's no spatters of solder or other ugliness that could cause shorts.

f. Peel the tape off, reload, and repeat. Once you've done the first two columns, you don't need to keep doing opposite sides. I actually like to load 2 adjacent columns (the ones right next to each other) because it's easier to align everything.

g. Unless you're some kind of Olympic soldering champ you'll be doing this for a couple of hours, so get comfortable, make sure to have a soothing beverage nearby, and take lots of breaks to stretch.

2) Solder the female headers around the perimeter

a. flip the LED board so the sockets are face down.



b. Arrange the female headers around the led board to make sure you have them all. Depending on the parts you get, there should be 5 or so headers per side, for instance 4 16-pin headers and an 8-pin header per side, adding up to 72 positions per side. Horizontally there are 74 holes, vertically there are 72 holes. You only need 72 header positions in each direction, an equal number on each side, because the vertical headers go all the way edge to edge, the horizontal rows fit between the vertical columns. You'll see what I mean when you start laying it out.



c. OMG, the headers don't fit next to each other! This is where the file or sandpaper comes in. (Note: Don't do this late at night while your room-mate or partner is trying to sleep - they will kill you). Take each header between thumb and forefinger and hold it firmly against the file, and file down each end a bit. 4 or 5 scrapes, then check, then 4 or 5 more, repeat. Keep the piece as square as possible to the file. Try not to file all the way down to where the little brass contact shows through. If this happens, make sure not to put 2 of these next to each other or you'll have a short.



d. Do this for a long time, working your way around, fitting the headers next to each other, making a little pile of phenolic dust. Don't solder anything, yet. Just get the headers to fit nicely together, then clean up the dust.





e. Now take the 40-section male headers, and going around, fit the long ends into the female headers. It's easier to fit two male headers next to each other if you partly pull them out, first, and push them in at the same time. You can also use the file if needed to make a little clearance. Twist off the excess headers by pinching and twisting hard with your fingers at the seam, or use a snipper. Save these extra pieces of male header because you'll need them later!



f. Now the male headers hold the female headers in place, all lined-up. Clever, eh? They keep everything lined-up while you solder.



g. Flip this all over carefully, making sure it doesn't come apart, and put it flat with a little downward pressure to make sure all the header ends are poking through the holes in the board equally all around. Now carefully solder each one in place. Be careful not to melt the ic sockets while doing this - it's a bit tight in there. I actually cheat a bit and sort of glob the solder on from one side. These are a little trickier to solder than the sockets since the header pin is thick and the solder pad is very small. The globbing thing actually helps a bit. Remember this is also a mechanical connection as well as electrical, so make it sturdy. But don't get carried away and make shorts! Use that solder-sucker without mercy.



h. After soldering all four rows of female headers into place, gently remove all the male headers you just inserted and put them aside. You don't want to accidentally damage them while pressing in the LED bargraphs in the next part.

3) Insert 112 LED bargraphs into the sockets

This is harder than it sounds. You'll want to be rested and decaffeinated for this.



a. Each color may have different markings, heights, and length of legs. It is important to think about this when designing your LED layout. You may need to snip some legs and not others. I find they actually work best if you leave the legs a little longer than they need to be. This lets the bargraphs nestle against each other nicely despite variations ion the cases. If they are all one color, your task is simpler, and you can usually just pop them all in as-is. Keep in mind a plexi sheet and sensors will go over the LEDs, so keeping them all perfectly flat relative to each other isn't a requirement for the stribe to work and look nice.



b. Make sure you know the proper orientation for the color(s) you will be using. The best way to determine this is to use a 1.5V battery, or a multimeter set to test continuity (this will send just enough juice to light the led without cooking it). Put the + on the left leg and the - on the right leg of the nearest LED. If it doesn't light up, flip the bargrpah 180 degrees and try again. This is how you want your bargraphs oriented: [+] on the left, [-] on the right.



c. These are fairly cheap-o bargraphs which I selected for their price. If you want to pop for some really nice bargraphs expect to pay about $150-$200 for 112 high-quality ones, unless you can get them in bulk (1000+ units) and then they're $90.

Meanwhile, back in the real kit, sometimes the legs may be bent or distorted, as they're made of thin wire instead of thicker legs like the fancy ones have, and transported stuck into styrofoam instead of nice protective tubes. Just carefully straighten the legs with a pliers, and make sure they're all lined up nicely before trying to insert them in a socket.





d. Starting at one end of the column of sockets, gently align the legs in the socket, and push. At a certain point they will all line up and you'll "pop" the socket into place. 99% of the time this means it worked, but it's a good idea to check each one with a magnifier afterwards to make sure, especially the first few. Almost every dead led in my experience has been the result of a bent LED leg that either missed the mark or folded in half during insertion, when I thought I'd done it perfectly. It will be frustrating getting these all in at first but eventually you'll get the feel for when they're in place and when to push and how hard to pop them in without messing up.



e. Take your time with this. As each column is loaded, take a strip of perf-board, or a thin metal ruler, and lay it in the space between the columns, then press the columns against the ruler and vice versa to line things up. I considered stuffing something in here to hold it all together, but it looks fine without.

To remove the bargraphs if it becomes necessary DON'T PULL THEM OUT BY HAND - unless you really like poking yourself with multiple really sharp wires in the thumb and/or forefinger, all at once, real hard. Trust me, you don't need to experience this. Instead, gently pry each bargraph up from underneath using something flat and stiff like this pair of scissors.



f. If you do mess up, like rip a leg off an LED or something, let me know: I have extra parts. The stribe will run fine with missing leds or even missing entire bars, so you'll still be able to play with it while waiting for parts.





TADA! You're done with the LED board! Set it aside.

Just a note here: I'm never entirely confident I'm NOT about to accidentally gloop some solder into a socket or something by accident. I often bow to the gods of humility and put some masking tape and/or foam over any delicate area in question, especially one that just took me hours and hours of careful work to solder, hint hint. This is your call.

Now it's time to build the DRIVER board.

Second: Build the Driver Board

Note that some of these pics are from earlier revs of the boards so they may vary slightly from the actual boards and parts. Resistors are always some weird size you didn't expect. Ceramic caps are the same. Sometimes they're giant and from 1942 surplus. Trust what's printed on the board, the part, the documentation, your meter, and common sense before trying to match the pictures.



Build steps:

0) Apply the 4-rubber feet. This might seem silly at this early stage, but it actually helps a lot with the assembly of the DRIVER board to have the feet in place. Just peel them off and stick them to a spot on each corner that doesn't interfere with a place that will be soldered, which is ALL of the little round holes/pads except in the 'yr circuit here' proto area. If you mess up you can peel the foot off and move it, no sweat.

1) Using a similar technique as w/ the LED board, using duck tape, solder the 16 24-position sockets in place. Make sure they are soldered in flat.



On one of the columns of 8, you'll notice there is one leg of the socket that is immediately adjacent to a hole that accepts a leg from another componnent. Leave this one un-soldered for now, to avoid accidentally filling the hole with solder. The notches in the sockets should point left to match the silk screen, and the printing on the chips should be right-side-up.



2) This part is repetitive, as you solder each set of MAX7221 driver components in. I like to put in all the electrolytic caps, duck tape them, solder them and snip them, then flip it over, peel off the tape, put in all the resistors, repeat, then do the round ceramic caps last. It's your call, whatever works for you. The only thing that's sensitive to polarity is the cylindrical electrolytic caps, and of course the MAX7221 chips need to point the correct direction (all the notches go left).

Triple check the polarity of the electrolytic caps before you solder. The negative leg has a big arrow with ---- on it next to the negative leg, so DON'T put this into the hole with the square pad. After you've triple-checked, tape them on with duck tape, flip the board and solder them up. The pads are close together so solder carefully.

3) Now you solder the male header pins in place. I've found the best way to do this is to grab the assembled LED board, and re-insert all of the male pins. Then flip it face down with pin ends up, and place the partially-assembled (from previous step) DRIVER board face down onto the pins. It might be best to do this without having the MAX7221 chips installed, yet (you didn't rush ahead and install the chips, did you?).

Put some weight on the board so the pin ends protrude through the DRIVER board evenly. I sometimes go around and do the corners first, applying pressure or placing something heavy (like a roll of solder) in the middle of the board, to keep everything lined-up as I solder the many edge pins to the bottom of the driver board.



Keep in mind this is sort of the final "mechanical" soldering step, so make sure the boards aren't too warped by your previous steps. You can make some adjustments here that will help keep the board flat on the four rubber feet, before you solder.

4) Once the pins are all soldered, you can pull the two boards apart, by gradually prying the male pins out of the long sockets, by gently but firmly prying at the corners of the two boards. Just keep going around pulling apart a little at a time and eventually it will pop apart into two pieces in your lap. This is how you will install the MAX7221 chips. Check for any loose or funky pins and re-solder if necessary.



And you're still not done!

5) solder-in the 8 10k pull-down resistors and 3-pin connectors for the sensors.



You should have an extra male 40-pin header or 2, if I counted right, but you'll also have some odd-numbered headers leftover from earlier steps. Before you solder the resistors, make 8 3-pin male header connectors by breaking up the male pin-connectors into 3-pin sections. If you have a 0.4d DRIVER board or later, these can just be soldered in straight up-and-down - load the resistors, drape the duck tape, tuck everything in, flip it over real careful so nothing moves, solder it up, snip the legs, done.



It's a little trickier if you have a 0.4c board or earlier, since you need to angle the 3-pin connectors outwards slightly to meet up with the Crimpflex connectors on the softpots, getting around the edge of the LED board (problem solved in 0.4d+). In this case I use a wood shishkebab skewer (see pic above) to set all the 3-pin units to the same angle before taping them. It gives you a reference-point and acts as a prop to hold everything in place while you tape it up. If you have a 0.4d DRIVER board or later (which most of you do) just solder these in straight up-and-down and they should reach perfectly. Could be some variation depending on form-factor of bargraphs (how thick) and thickness of your touch surface, but when you attach the strips (later) you can calibrate a bit by hand to make things match up.



Comes out nice if you take your time.

6) Install the push-button switch and 10k resistor reset circuit.



As far as I can tell the switch is immune to orientation, just line up the long side with the farthest pins. I can usually pop this in if I do it before installing the Arduino sockets. If I forget or it's giving me a hard time sometimes I straighten the pins a bit with pliers. It's designed to just pop in, though.

There's a way to wire the MINI so it will auto-re-start after a time-out, so you don't need to hit the little switch to upload new firmware and/or reset the board. I'm not sure yet how valuable this feature is, as I don't mind pressing the button. But the Arduino Diecemila and Wiring boards implement this feature so it should be pretty straightforward to figure out. Also, you can replace this switch with your own (intermittent) switch and some long leads if you plan to build a case that covers this area. Will need to be addressed in future versions (maybe there's a better place to put the switch)

7) Build sockets for the Arduinos.

Build the sockets out of female headers. Then solder additional male header pins to the Arduinos to bring all the connections to the sockets. This sounds simple but there are some complications that I've been through seveal times by now so maybe I can save you some time.


Your Arduino MINI will come pre-loaded with the most recent Stribe firmware. You can plug it into the dual row of female sockets, before installing the little 2x2 pin setup, just to test if you like. You'll notice the left 4 sensors act correctly, while the right four just sort of "float" and follow the value of the other sensors. It's kind of neat and non-linear to play with if that sort of thing interests you.

Several extra header pins are soldered to the Arduino USB stamp, even though all the pins aren't used in the stribe circuit, to provide a more-solid physical connection to the USB port. 4 Extra pins (the 2x2 male and female headers provided with the kit) are added to the Arduino MINI to connect 4 of the ADCs to the stribe circuit board, for use by the right 4 sensors. Use the leftover male header pins from the kit to build these to the correct length.




One trick is to hit the pins on the Arduinos with a magic marker along the edges as a visual guide so you can clip them all pretty evenly. In the end I just did each one by eye and they came out fine. Just don't clip them too short.



Use a high-quality and sharp snipper for this to avoid damaging the Arduinos with lots of yanking and cursing. If necessary, lightly file off any extra bits hanging off to make sure they slide nice into the socket. Remember this stuff is all sensitive to static so go easy and stay grounded.

Some notes:

On the Arduino MINI, there are 4 ADC's that are not wired to pins. In the kit I provide a square 2x2 male header and matching female 2x2 header. The male pins solder to the Arduino MINI, and these to connect to the stribe DRIVER board thru the female socket.

Similarly, the Arduino USB stamp does not provide a full complement of pins, just a few near one end. To strengthen the connection, even though I don't use the extra pins, I add male header pins to the USB stamp to make a more solid base for it. I use extra headers to accomplish this.



I find it easier to assemble everything onto the stamps, then solder them in. Just don't spend too much time soldering on the Aruinos - you don't want to cook anything.



Solder the four pin-ends protruding through the Arduino MINI after all the pins are trimmed to the correct length and the female headers are soldered to the Driver board and so on. I like to solder these last as they are a good indicator of how well I've lined-up everything else.

Similarly, assemble the female header/sockets to the stamp with the extra male pins first, fit everything to the board, then solder the female sockets in place. Solder the pins to the stamp as the final step. It's important to do this part carefully since this is the Stribe's main connection to your computer, and power. There are lots of little diodes and parts on the Arduinos that are snsitive to heat, so solder these pins quickly.








8) insert the 16 MAX7221s

Make sure the board is right side up. All notches go left. Stay grounded, don't rush, don't bend pins. Make sure they all go thunk in the sockets.

TADA!

If you removed them, put the Arduinos back in their sockets. This might be a good time to use your continuity tester to make sure all the used connections on the Arduinos have continuity to the other side of the DRIVER board.

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Now plug it in to a USB port! [Note: the stribe definitely draws more than it's fair share of USB power - so unplug other up-stream USB devices first. Once the stribe is stable, plug other USB devices back in one at a time].

It's actually better to do the LED test before you attach the sensors and and faceplate and everything. In case there's a problem you haven't taped everything together already.

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You should see the small yellow LEDs on the Arduino USB flicker briefly, then a few seconds later the Stribe will run through it's default startup sequence, which is currently set to cycle quickly 5 times (you an adjust this in firmware or via Max).



Okay! It works perfectly!

(I'll add debugging steps here, later - usually a dead LED means you hurried - re-heat the solder joints, check the sockets, suish things together, wiggle a bit. You know.).

Now, let's move on to attaching the delicious touch surface.

Third: Surface and Sensors

This is the most visible part of the build, so keep your work area and hands clean and try not get your fingerprints all over everything. It won't be like AWFUL if you're not all neat and tidy about it, and eventually you'll sweat all over it making futuristic music - but you'll be glad you did.

This is also the most forgiving aspect of the build, as you may have to do it several times to change colors of bargraphs or experiment with different touch surfaces, both overlays and underlays, and so I made this section easy to modify.

If you build it carefully you should be able to remove the touch sheet and sensors as a single unit, repeatedly, as-needed. The connectors for the sensors are simple 3-hole female connectors that fit onto the DRIVER board and slip on and off easily. Maybe a dab from a glue-gun at some point. They are sometimes easier to get on and off with the Arduinos removed.



Here's the LED board with the plexiglas sheet attached by thin strips of long-lasting transparent tape along each edge. [I use Staples "Long-Lasting" packing tape, which is thick, and cut it into thin strips with a ruler and x-acto. I get axactly the width I need, it's long lasting, I can cut it off and start over if I need to. Good stuff.]

The tape holds the sheet in place before the sensors go on, and also provides a tight band around the individual LED bargraphs, holding them together. It's a good idea to have the LEDs lined up as nicely as possible before you do this step. Once the sheet is in place, you have a nice solid surface to attach the sensors onto. The sensors will :"break-in over time. It's a good idea to burnish the clear plastic where the clear sticker adheres to the plexi while it's clean and new to remove any "fish-eye type issues. Over time the sensors become more reliable as they kind of "break in" and the connectors all settle.



Now connect the sensors to the Driver board, leaving the "3M" backing in place (trust me). One by one, unpeel the backing and carefully lay the sensor onto the plexiglas. Try to leave the top part of the sensor loose and line the sensor up to the second or third led - keep them all the same. Keep in mind the sensor is physically slightly longer than the 64 LEDs. The top 3 and bottom 3 LEDs do not light up. So center the active part of the strip in the column of LEDs.

Since the sensor is an off-the-shelf part designed for generic applications, the bus-bar runs though the left column of LEDs. And you'll see the maker's name in black letters. Neither of these are really that noticeable once it's assembled and in use, but they mark it as a prototype for sure.