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.