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Absolutely Psychotic! I’m pushing myself to finish my senior design project as soon as humanly possible so I can have it done and over with and not find myself in the Senior Design Lab hours before the project is due.

Fortunately! The development board I designed and built works. Simply as that, everything works. Of course there were about 4 prototype PCBs milled out before I got one I felt confident enough in to build around, it worked.

This is the board that I ended up putting my chip on (actually, this is the next board i’ll make, this one has the ISP connected properly and a few minor modifications for clarity added):

As you might notice, the ISP header wasn’t quite connected…. That will require a re-mill, but once I hooked up the appropriate wires, the ISP worked and I was able to get those LEDs to light up the lab! I think I might have mentioned previously that there isn’t a through hole tool available in the lab so that was an absolute nightmare soldering on the bottom and tops of the pin headers just to get the two sides of the board hooked up right. Well, today (too late for my board) they got the through hole kits and we should be able to take advantage of that for the next mill of the board.

Some things I learned milling this board 4 times:

• Always provide space for as much pad layout of discrete components as possible, its helps them line up properly during the reflow process. For example, its tempting to run power lines across a whole group of resistors when they’re lined up properly, but it doesn’t alow for the surface tension of the paste/pad combination to line the component up. It also makes the PCB look a little unprofessional.
• It pays to mill out the board/revision on the PCB similar to the silkscreening method the “professional” pcbs get. This is good for keeping track of your boards for the obvious reasons.
• Print off all your datasheets. It is highly inconvenient trying to read the data sheet on the computer. Maybe that’s because I only have a laptop, but most engineers I know tend to agree. Its easier to thumb through and grab the datasheet unless your OS has some type of advanced system indexing (such as seen in that search thing in OSX and Windows Vista) which would make it doable.
• Take advantage of online forums. AVRFreaks.net made my project a huge success and very enjoyable. Knowing you have people that can help makes a HUGE difference in your confidence factor when undertaking new projects. Be sure and give back to the community though….
• In terms of priorities when it comes to projects with deadlines consider the fastest way to get from point A to point B in terms of time first, then money. The money won’t be there if the deadline passes and if you spend too much money meeting or beating the deadline, you just wasted time and gained nothing. Its a delicate balancing act. If I had to do something different in the future, I think I would have purchased the TQFP adapter for the Atmega 128 earlier in the game to speed up development and drop it in its custom circuit later. I essentially created my own development platform for the chip as opposed to buying it. I spent more money than the development platform would have cost, but what I gained in knowledge and experience can’t be quantified monetarily. I think the term is “priceless.”
• Organize, organize, organize. The benefits of organization can’t be overstressed. If nothing else is going right, having everything where you expect it to be can be your bridge over troubled water (for lack of a better analogy).

Tonight, or last night as its 2:00 am, I reflowed my first SMD PCB using a commercial toaster oven. I bought a cheap unit from Wal-Mart that supposedly outputs 1350 Watts and has 4 burners. The process was pretty straightforward: Solder Paste your pads, lay down the components, bake… I had to follow a pretty heavily modified reflow profile as this oven doesn’t really heat up that quick, either that or I was too fatigued to see the reflow process actually happening.. In any case, it went well and I’ll have pics shortly…

One problem was that Eagle made the pads look to be WAAY too big for the 0805 capacitors. It worked nonetheless. The other thing wierd that happened was that in my juvenile rush to get the board milled and populated, I neglected to select the proper footprint for my inductor and two of the capacitors, specifically the ones that do power filtering… Not a good thing…. I set them as 1206 devices and once the board is milled, its too late (I’m soo sick of the senior design lab its not even funny) so I tried to put the 0805 caps in the 1206 pads and created an unintentional power plane on the PCB which SUCKED. Took me 2 and a half hours to figure out why the LEDs would light if I placed the multimeter on the power line and grounded an arbitrary location on the board.

The other thing that needs to be addresed is the fact that I can’t do through hole plating on boards that come from the PCB mill. We have the tools, but the plating ?rivets? apparently have lost their way. The thing costs $300 and @ this point in the game, we can wait. Would be nice… As an alternative i’ll have to do something REALLY tricky to get the port connection headers to make contact c/ both layers of the board. I already came up with a solution and will be posting pics once I get to it tomorrow…

For now, I gotta get my madden skills right…

I’ll probably be changing this a LOT, but I do want to keep a somewhat centralized theme, so finding things doesn’t get too chaotic. The search is on!

On a side note, I’m not sure if I want to have the type of site where I’m posting a lot of “useless” information, such as this post. This doesn’t really add any value to my life, or anyone else’s life. Can you learn from this? Do I really even need to say this? Interesting questions…

I said it anyway. If someone wants something, anything, they can find it if they’re willing to search hard enough.

LEACHING!

That’s essentially what i’ve been doing since I’ve gotten on the internet.. Leaning, reading and retaining countless volumes of information and giving nothing back.

The other reason I created this is because i’d really like to document and track things I do so I can be more productive.

I’ll more than likely have a lot of stuff about engineering (my thing), BBQing (my other thing) and occasionally some random stuff about life.

Well, lets see how it goes!