5. Electronics Production¶

That right there was my Brian Board¶

So you’re probably thinking, how’d you get that thing milled out? Well, I’ll explain even more than milling it out. I’ll guide you through milling, soldering, and programming this wonderful board up.

Milling¶

First things first, you’re gonna want a Modela mill. Modela mills are pretty cost efficient, small, and pretty easy to use. Only thing is is that they make pretty chunky circuits (none of that fine stuff for you) and use mods. Now, a lot of people don’t like mods, especially the poeple at Lorain. Luckily, Professor Gershenfeld made my dad make his final project last year with a mods interface. So when we got to Lorain and found out they hadn’t used the machine for a year and a half, my dad knew how to step in. This is a process I wasn’t a huge part of, but its a really weird thing that not a lot of people have to deal with. I learned its very useful to learn mods so that I can do the same thing my dad did and help solve a problem.

Now you’re gonna want to switch out some of your drill bits. For engraving the thing and making all your connections and what not, you’re gonna want to use a 1/64th in. bit. Noticed how small that is? Well lets just say that size is proportional to ability to break. Smaller the size, bigger the risk in breaking it. Another thing I noticed is that the smaller the tool is, the harder it is to find it. Modela’s require some very small hex keys, so I would just invest in having a little pouch on the side of yours where you always keep it instead of having to sort through a bunch of hex keys looking for on that might fit. So what you want to do now is loosen the bolt part of the mill. Gently take out whatever bit was in there and make sure it doesn’t directly drop down. Then gently put the 1/64th bit in and tighten with the hex key again. Make sure the bit is secure by tapping the side a bit.

Once you got the machine all set up, tape your board down on the base of the mill. For the Modela, it’s easier to use double sided tape. For machines like the LPKF, masking tape is fine. The reason why you want to use double sided tape is because you don’t want you piece popping out mid cut. I alway’s knew there was a lot of guesstimating in fabrication, but you gotta get good at it if you want to succeed. So, guesstimate approxiametly where your board is going to be and stick a piece of doubel sided tape on the back. Then, stick some strips of double sided tape on the back edges. Place the baord down and bam. Good to go.

Let’s actually get the board cut out now. So, first you want to set the material width, height, and length using mods. Once done with that, hit the run button on mods and start cutting your board. You’ll want to make sure that you don’t inhale any of the dust when it’s milling. Once it’s finished it’s first pass of engraving out the paths, set it up for the cutting part. Once finished cutting, you can now remove the piece and pop it out. You now have your first board!

Soldering¶

Here is another super difficult part. Soldering takes some time, practice, and lots and lots of flux. While some people might say that flux is just a crutch for bad solderers, ignore them. Their boards will be spiky while your’s will be beautiful and smooth. The best way to solder in my opinion is to take on resistors and other small pieces first, then move into the ATTiny and Header. Headers can be pretty hard to put on, especially with tweezers. I’ve never really found a nice way to tack it on nicely. This is why I used play dough to help with the heat coming from the pins. I clean the play dough off and continue soldering.

Most of your solder will have a semi-dull look. Not really void of all shine, but it’s about the shine of a lightly used nickel. Here is a little list of tips for clean up:

Do not use water -> Use 98% alcohol
Try to use the most liquid, non-sticky flux you can
Treat your board very carefully

After you’re done soldering make sure to clean off your board of anything that may have gotten on it. Once you feel like you’ve completed those steps, it’s time to program.

Programming¶

This was my first dive into programming my own board with a makefile, so it of course took at least a couple days to do it. I’d say this is what got me behind the most since it’s so easy to just give up and flop on yourself. Enough of that, lets get into the steps.

For this week, I used this site (http://fab.cba.mit.edu/classes/863.16/doc/projects/ftsmin/index.html) and my dad’s webpage so I wouldn’t go into the dark with it. With their help, I got about halfway there, but Macs aren’t the best at programming. Now, Chris Rohal, one of my instructors, he has this real fancy Dell laptop. Now this laptop has most everything you need to program any board on it. So I plug my board in it and Chris starts just typing in so many different things into the computer that I know weren’t ‘make clean’ or ‘make hex,’ but I never really got to understand what was going on from the program running so fast. Sure, I got pictures and screenshots, but it was pretty rough.

So, here it is. The actual tutorial:

get your zip file (fts_firmware_bdm_v1.zip) for whatever system you’re working on
run Make
open fts_firmware.hex (another file that comes up after running make)
next, edit your makefile to fit with the programmer you are using (I used usbtiny, like most others)
make sure your red LED is on after you plug your programmer into your computer (with a dongle, of course. you can fry your board if you aren’t careful!)
plug in your programmer to match with your pin one and run ‘make flash’ through terminal
run make fuse afterwards
if you are using Linux, run lsusb and see if the programmer appears. if you are running on OSX, go to About This Device, then More Prefrences, then USBs. usbTiny should show up!
^^ the step above is super important after this soft if it doesn’t work don’t go on any farther!
run ‘make rstdisbl’ (this makes the Reset pin turn into a GPI/O and you’ll be very sad if you do this incorrectly)
Voila! Just desolder the bridge that you needed before are you’re all set!