Puma board for FreeEMS

Marcos' unmaintained, but still in-use, Puma for FreeEMS circuit board/hardware design!
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nitrousnrg
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Re: FreeEMS for Argentina

Post by nitrousnrg »

The text is between the pads, and overlaps the pads, such that much of the silk screen will be blanked out.
Oh, I see. I started moving references to make them readable, and I'll change the diodes reference size as soon as I understand how to do it. The same about tenting, I read that page a while ago, but never put it in practice.

About the cases, I'm still searching... I'll speak up when I find something.
I've also seen folks use a toaster, on it's side with the spring mechanism disable, for small boards. When done this way, you can make a reflow oven for under $100. I used some $18 SSR's from futurlec. It took them some months for the parts to arrive, but for the price, you can't beat these SSR's.
http://www.futurlec.com/Relays/SSR40A.shtml
I went with the infrawave oven because it combines infrared and conduction, and it's large enough to do a typical PCB. The conduction creates air patterns that help smooth out hot spots often found in pure infrared ovens.
Cool. There are many ways to try anyway. I'd like to try the hot plate first.
No pat on the back required, a much better way to say thanks is to complete this project and make it run the vehicle. Keep it up and I'll assist in what ways I can.
Okay, hands on ;-)
Marcos
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jharvey
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Re: FreeEMS for Argentina

Post by jharvey »

Hot plate you say, have you found this fellow yet?

http://www.kd5ssj.com/solderpaste/smt-tools-and-process
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nitrousnrg
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Re: FreeEMS for Argentina

Post by nitrousnrg »

Nope.
100°C is a little low I think; I'm looking for something capable of reach 240° at least (without a hot air gun)
And electric, I recently made an AC controller, so I could adapt it to regulate the power delivered to the plate :)
Marcos
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nitrousnrg
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Re: FreeEMS for Argentina

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Ha! I just realized that this board (99.95 mm × X mm × 130mm) is really close to the dimensions of a 3.5'' HDD (101.6 mm × 25.4 mm × 146 mm). Now looking forward to HDD cases too.

I'm thinking in the IAC controller (both stepper and solenoid), when I organize that in my mind I'll post it up.
Marcos
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Fred
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Re: FreeEMS for Argentina

Post by Fred »

"I'm thinking about the IAC controller" - cool, looking forward to reading about it. Put up a new thread in firmware when you do :-)

Fred.
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nitrousnrg
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Re: FreeEMS for Argentina

Post by nitrousnrg »

what do you guys think about this stepper controller?
http://search.digikey.com/scripts/DkSea ... 17E2%23-ND
datasheet at:
http://semicon.njr.co.jp/njr/hp/fileDow ... ediaId=685

Its available on digikey and mouser, small outline, stands 125°C (if you don't abuse with the current delivered to the coils). Its controlled with two signals (DIRECTION and STEP). I was thinking *about* reusing the power outputs to create an H-bridge. Silly me, a stepper needs two H bridges, and involves too many transistors.

Well, looking forward for opinions :-)
I'm closer to make an order
Marcos
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jharvey
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Re: FreeEMS for Argentina

Post by jharvey »

How about the MC33879. It offers some extra feed back mechanisms and can be set for stepper operation as well as other features.
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Fred
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Re: FreeEMS for Argentina

Post by Fred »

I have no comments on your stepper stuff.
nitrousnrg wrote:Well, looking forward for opinions :-)
I'm closer to make an order
But, you probably want something like this :
nitrousnrg wrote:Well, (implied: I'm) looking forward to (optional: hearing) your opinions :-)
I'm closer to making an order
You don't need the stuff in brackets, but its slangish to not use "I'm" and it's more complete/explicit to use "hearing"

Fred.
DIYEFI.org - where Open Source means Open Source, and Free means Freedom
FreeEMS.org - the open source engine management system
FreeEMS dev diary and its comments thread and my turbo truck!
n00bs, do NOT PM or email tech questions! Use the forum!
The ever growing list of FreeEMS success stories!
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nitrousnrg
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Re: FreeEMS for Argentina

Post by nitrousnrg »

jharvey wrote:How about the MC33879. It offers some extra feed back mechanisms and can be set for stepper operation as well as other features.
Yeah, thats a cool IC, but it seems I can't buy it. Digikey doesn't have it in stock, neither do mouser, and freescale.com says that there is a 24 week lead time, quite big minimum orders, and no distributor available. Mouser says that mc338** are LC o NRND (end of life or not recomended for new designs). Ufa!

Good input, if I find something else I'll post it. So far, I'm staying with the JNM3517. Diagnosis capabilities are a good add-ons, it'd be nice to see a "check <actuator>" pop up in my PC. I could be ok with just current limitation,though.
You don't need the stuff in brackets, but its slangish to not use "I'm" and it's more complete/explicit to use "hearing"
mmm, big difference there. In spanish I avoid to make references for myself too much. Thats why I don't use "yo" a lot, it is usually implied, and feels kind of "I'm the center of the universe" if you over use it. It could be a personal impression, but I'm not the only one who has it, tho.
"Tengo un auto" and "Yo tengo un auto" means the same, but I'd prefer the former.
to/for: grrr... little words...
Marcos
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Re: FreeEMS for Argentina

Post by hamster »

Just read through the thread to date and have some suggestions:

1) In order to keep a MOSFET cool and efficient, you have to drive it HARD on and off. Basically, the gate will look like a capacitor to your driver, so you have to charge the capacitor to get the MOSFET to both turn on and off. If you turn it on/off too slow, it spends too much time in the partially conductive region and it'll run warm and your output pulses will not be sharp. The MOSFET's gate has this wacky knee curve of charging that represents how fully the MOSFET is driven on and off. I recently designed a q-switch driver for some laser stuff at work where I needed to turn on a 3kV source in a few nanoseconds, and designing for that was tough.

I'd really suggest using a MOSFET driver like a MIC4452. For ignition use, the turn off time is the most critical part, as you have some amount of time to charge the coil (although again you want to stay out of the partially conductive region or risk running really warm). A push-pull driver approach works really well, using a MIC4452 and a MIC4451. The other bonus is that the MOSFET drivers can deliver chunky amps to the MOSFET to get the job done, and give you a fairly isolated input from your uC that is high impedance (in fact, the MIC4452 has a totally separate Vdd for driving the gate at whatever voltage if you want to not use logic level MOSFETs).

I think a IGBT might be a little better for driving these guys though, and that's where I am aiming to go with my design once I get there. Dedicated IGN drivers are nice too, but I'm not entirely convinced you need them yet.

As for the snubber diode, you certainly want to let the coil flyback and not snub it too early. You are more concerned with component death than trying to snub anything. I built a hacky rev limiter for the old electronic Kettering style ignition on my motorcycle and discovered this on my first attempt.

2) The $20 toaster oven works fantastic for SMD. Just really, really follow the reflow curve of your solder. The first time I did it I just cranked it up, and melted my boards into goo. Oops. Typically, for the Kester solder I have been using, I put the board in the oven on the metal tray, crank it to about 100C for about 4 minutes to bake the moisture, about 180C to get the flux doing its job for 2 minutes, and then crank it as high as it will go (around 280C on mine) and watch closely. About 50 seconds in your solder will go molten and start to shine, and all your parts will yank into perfect position via surface tension. Leave the heat on for a little more until everything has flowed and you don't have any more spots of dull colored solder, and then turn off the heat and carefully open the door. The total time at the last step should never exceed 1:40, 2 minutes tops, or else the PCB will melt. Let them cool to room temp. You may have to un-bridge some spots or re-flow others (big SMD caps don't seem to reflow well), but I've never had any real issues with the final result.
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