Whelp, no turning back now.

[marshallh]

Ill be honest with my pricing and will offer it as low as I can while still making it worth my time. I plan on making this into a company / carreer, and I need to eat, so there will be some profit involved, but im not much of a capitalist and would honestly give them away for free if I could.

I'm just curious, how much of your own expense are you covering right now? I am at the tail end of a project that's taken me over a year, and I will tell you this; people will PLEAD and BEG for you to lower your price, NO MATTER what it is. Also, while money will not seem like a huge deal now, because it's interesting, there's a good chance during the tail end of the process (the mind-numbing stuff) you will be forcing yourself with all your effort just to work on the damn thing, and money is a HUGE reason to keep going.

Set your price high. You can always lower it later but it's VERY hard to raise. You absolutely must make this worth your time and effort. At the end of this project you'll realize how much hidden work / corner case finding / idiot proofing has to be done, NEVER short change yourself or let others do it to you. It's one thing to be an engineer working for someone else, and another entirely to be a one man show.

Pretty ambitious, enjoy the project.

Just a hint since I've done something similar in the past, and now do it for a livingish... document everything before you start writing code. The key to a successful embedded layout is organization, not quality of code... you would be amazed at how simple to understand somee of the Powertrain code running on your PCM is. Oh, and I would go as simple as possible for your first pass. You're going to run into EMI problem when it gets to the hardware part.

This is super true, DOCUMENTATION, don't feel like you have to plan every single thing in advance, but you will need docs to retain your sanity. Your mind starts to do weird things under stress.
I have a 12 page PDF that I've been adding to as my project's been progressing, stuff like hardware register definitions, how to use the hardware, pitfalls to be aware of, etc.
Consistency with your docs and your code is crucial. Comment the shit out of your code.

PIC is a good choice, I would stay away from AVRs because Atmel loves to EOL products whenever it feels like it.

Anyway, if you have any questions feel free to PM me, I could write a book with all the numerous things I've had to learn over the past while.

[x2percentmilk]

First of all let me say thank you guys for all of the interest, while I will probably still finish this project for myself, the interest is what keep me from shelving it entirely.
Also, thank you marshallh for the tips. My head has already started doing some crazy things (I cant believe its April 12th already!!). Ill let you know if I have any issues. I am covering all of my own expenses right now, but they are manageable right now.

As an update: Hardware is starting to take shape. Initial tests of the injector circuits seem fine, though I wont really know for sure until I test them on the car, which I hope to start doing sometime next week. Software is really my biggest concern right now, as I've fallen a bit behind and have nothing more than my plan and flow charts. Had a few set backs with the PIC and my surface mount soldering ability, so I just now got the thing functioning an recognized by MPLAB. Part of me wishes I just sprung for a fully featured development board to save time.

I am going to have to buy a VR4/TT early this summer so I can really start making some progress. On a side, I also have someone into VW's who is interested.

[Chris95RT]

I don't know what package type you got from Microchip, but I would give something like this a serious look: SURFBOARDS* 9000 SERIES FOR I.C.s. But please get away from bread boarding these things, the EMI the transients will generate because of how crappy the breadboard is will have you chasing your tail.

Also, spring for the development board/kit; well worth the cost and you get something you can develop more things on in the future.

[STLVR4]

I really hope you can figure this out and stick with it.

Been waiting for an opportunity like this for toooooo long.

Good luck.

Subscribed.

[familyMAN]

Interested in seeing how this turns out!

[x2percentmilk]

The chip is a TQFP 100 pin 0.5 mm ping spacing. I ordered similar boards to what you showed me, but the pins were so small that even with somewhat decent technique and a boat load of solder wick I still had bridges that I cant even see with a 40X magnifying glass. Theyre so small my multimeter doesnt beep for continuity, but displays some high numbers. I ended up buying a board from microchip with the pin already mounted and the necessary capacitors already mounted. If I cant get this thing working as Id like by next week ill have to overnight a development board or something and pull a few all-nighters.

Thanks guys, will continue with the updates!

[Chris95RT]

Yeikes that's pretty fine pitch! That kind of part really needs some fine fine solder with a really fine tip and usually some flux; usually a reflow oven is used for something like that. Hopefully you can get a breakout board in place of it, when I was doing development on an 8 bit ST part a while back they gave made some chincy breakout board which made probing signals and development in general really easy.

Your other bet is to make your own using something like Altium, good luck though!

[x2percentmilk]

Youre telling me! was surprised when I opened the package. A breakout board ended up saving me.

Good news: PIC is finally configured and running properly. Time to start writing code

[marshallh]

Relax, you can solder those no problem. It sounds like you need to be using more flux. Look into buying flux pens -- they're like sharpies, except you "draw" flux with them. Kester is the one brand I know of that makes them.

Sparkfun sells them, also look into getting a set of curved SMD tweezers. I got a set for $4 from dealextreme.

I have a Weller butane iron and I use it for pretty much everything. I have soldered pqfp-208 FPGAs no problem with it. Works best to add just a bit of flux before you run the iron+solder down the row of pins. Add a bit more flux when using the solder wick or you'll have zero luck.

Allelectronics.com sells some awesome solder wick that's flux impregnated, my only gripe is that it's almost too much flux ! haha

Highest percentage rubbing alcohol you can get for cleaning. I use 91% from walmart.

Something to keep in mind as you start adding sensors and such, if weird shit starts happening (that you can't trace down to the code), look to your hardware. Proper decoupling and clean power go a long way. If you suspect a noise issue somewhere use shielding to see if you can track it down.

Eventually when you make a pcb, let me know, i have more tips there too

oh, about that flux again, it's a very good idea to add a bit of flux and reflow parts after you're completely finished assmebling. In the pic below, right below the L in Altera, there was a stupidly small solder whisker. Caused corruption on that data lines. Couldn't even see it, multimeter didn't even pick it up like you described. But once I reflowed with flux and cleaned it worked great.


edit: one more thing, PLEASE do not make the mistake of using blue/black/red silkscreen on prototype pcbs! You can hardly see shit, even with the camera flash. Working > looks cool, haha

[x2percentmilk]

Thanks for the tips. I do actually have the kester flux pen you mentioned, and a Hakko 936 with a few different tips. For now the pre-assembled board is working, but I am going to go back to those other ones and see if I can fix them so I have some backup chips during development, not to mention its a lot cheaper. I just couldn't budget anymore time into bridges that I couldn't see haha. 3 weeks left before this is all due. The solder wick impregnated with flux sounds super handy, im going to have to pick some of that up. Final product will have surface mount components professionally assembled.

Ill let you know if I start having any PCB questions. That blue does look pretty awesome :P