BOM straightening

Marcos' unmaintained, but still in-use, Puma for FreeEMS circuit board/hardware design!
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AbeFM
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BOM straightening

Post by AbeFM »

I can't speak for everyone else, but the biggest single issue keeping people from testing is... we all have PCBs, and no idea what to put on them! There's a nice spreadsheet that someone made, but, apparently it's got some wrong parts on it, etc.

I found stuff that digikey actually sells, but, I don't really have any clue what to order. I've made a couple spreadsheets:

http://tinyurl.com/4y5zoo2
Google Docs Spreadsheet, last tab exports to Digikey

And I have a BOM which tells you what's in stock and minimum quantities, etc, on digikey. But still NO CLUE is any of this is right. Is there someone out there who knows how to fix this spreadsheet, verify it, or make another?

Every time we talk about this on IRC there is lots of "yes yes" but no progress.

Anyway, wanted to post this thread.
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Fred
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Re: BOM straightening

Post by Fred »

Plus one, the BOM and the "fix this stuff" instructions are kinda tied together, because without the "fix this stuff" you don't really know what the BOM should have in it, as things change with the fixes. Make sense?

Jammi wants to do an online data driven BOM and instruction generator page, which I think is a FABULOUS idea, maybe the best path is to migrate the various distributed spreadsheets into a Puma-Spin1-BOM-Data repo and a repo holding a site that can process that data and display it and output a BOM in some format.

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AbeFM
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Re: BOM straightening

Post by AbeFM »

After having Marcos review the BOM as is lies today:


(12:44:low Z AbeFM?

(12:59:no atm pressure?

(1:09:you have something like a hall sensor, so you don't need the MAX9924?

(1:10:The BOM seems good to me

(1:16:order some extra 33v zeners, but in a smaller package

(1:18:but I guess you're going to use it in the default linear mode

(1:19:so no need to have a 5W znere in there


--------------
My thoughts: We need to get it right and understand it first, you can't have a webpage which autogenerates crap. :-)
With any luck, we should be in a position for it in the next day or two, though.

---------------

More comments:

1) MOSFETs unavailable, looking for suitable replacements
http://search.digikey.com/scripts/DkSea ... P30N06L-ND
$1.02, 60V, 32A, 35mOhm
http://search.digikey.com/scripts/DkSea ... P50N06L-ND
$1.25, 60V, 50A, 21mOhm

To my mind, 32 amps is plenty, and while I like the lower resistance, we're only talking 500mW verses 700.... Well, ok, let's spend the 20 cents. Of course, at 2 amps (more likely for a fuel pump, honestly 1 amp is more like it) it's only 50 mW. I hope the pin-out works.



2) EGT
I found this:
http://search.digikey.com/scripts/DkSea ... 96-8009-ND 12V LDO (already posted) but I don't know if 150 mA is enough
Turns out Marcos likes it, so I'm going with it. Only costs 68 cents, the bigger cost (by far!) is the EGT readout chip itself.
AD8497ARMZ-ND is the IC itself, only $5.


3) MAP
http://search.digikey.com/scripts/DkSea ... 300AC6U-ND
This is smaller, cheaper, and supports a sensible boost level for I-4's. $9.99 and does 2.85 bar (27 psi) verses the 2.5 bar (i.e. 21 psi). Different footprint, but you're at least getting a range that you won't run out of until you really get silly with the boost.
The "normal" MS sensor (MPX4250AP-ND) would actually be my choice for baro. Even though you can use: (MPX4100A-ND) http://search.digikey.com/scripts/DkSea ... ND&x=0&y=0
there are two issues: One, it only reads vacuum, and do you really need that extra accuracy? And two: No port! Sometimes you just want to do logging. I'd actually be pretty tempted to put on one of the differential parts - awesome for monitoring drop across intercooler or throttle plate. You could even use it for your exhaust system. With a long, carefully done pipe, you could probably measure drop across your turbo and/or wastegate. :-) http://dkc3.digikey.com/PDF/US2011/P2748.pdf for some ideas.

4) USB port
What is a good/the best USB port to use? http://search.digikey.com/scripts/DkSea ... ND&x=0&y=0 is on the BOM but I think this is changed??

4b) USB Cable
http://search.digikey.com/scripts/DkSea ... ND&x=0&y=0 probably also isn't needed.

not-here-1) While I don't need VR, I might go to it someday. Anyway, for the sake of completeness:

MAX9924UAUB 1 x Differential 1V/V
MAX9925AUB 1 x Operational Externally Set
MAX9926UAEE 2 x Differential 1V/V
MAX9927AEE 2 x Operational Externally Se

Why WOULDN'T we use the MAX9926, which supports two channels?? $3.77 verses $2.60 for the stand alone.

As for me, it's op-amp city, it works so bleedin' well, there's no reason not to. At least, I think it works well, plus it's what Mazda ships from the factory, so they can't be too bad.

not-here-2) Low-Z injector Controllers
http://www.infineon.com/dgdl/TLE6270_DS ... 20e4701141

OMG I love this chip. Unless I'm missing something. I guess this doesn't really belong in the BOM section. Same for the one above it.

2.3A hold current, fine for anything low or high z. 0.3 ohm is a little high, but not a killer.



5) XOR gate, shortage of parts?
MC74HC86ADR2GOSCT-ND - the XOR gates, there are very few of these in stock, not sure what to do about it. At least they are cheap.

6) Peak and Hold Zeners:
From the comment at the start of the post 1N5364BRLGOSCT (5W Zener) isn't needed. But I'm not sure what footprint I want, or what size. http://search.digikey.com/scripts/DkSea ... ENER%2033V will help me find it, but I'm at a loss. What IS a good size?

7) P&H Darlington
I'm not sure why I took this off my list: http://search.digikey.com/scripts/DkSea ... ND&x=0&y=0
I guess I'm not sure what the circuit looks like. I probably removed it because I already own some, but, for clarification, are these still the best part to use?

8) Fuse Block
http://search.digikey.com/scripts/DkSea ... ND&x=0&y=0
I heard we're not using these? I guess I'm neither for not against it. It really shouldn't be needed, then again, it won't hurt anything. I'd probably rather see a blade fuse like the rest of the car uses, no? They are pretty standard and you can get it anyway, you could also solder one in on leads, available at any FLAPS

9) Stepper Motor Driver
I keep forgetting some cars have these. Seems silly to me. :-) 620-1158-1-ND The point is, the part is discontinued so if you need this act now!
If you don't, don't buy it, it's pricey!
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jharvey
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Re: BOM straightening

Post by jharvey »

AbeFM wrote:1) MOSFETs unavailable, looking for suitable replacements
Stingray uses IRGB14C40LPBF
AbeFM wrote:2) EGT
EGT on Puma Spin1 is broken, you probably want to avoid, or plan for some massive rework.
AbeFM wrote:4) USB port
Have you seen the modes? There is a picture that shows how to use a standard micro or mini connector. Future spins will use either a micro or mini.
AbeFM wrote:While I don't need VR, I might go to it someday. Anyway, for the sake of completeness:
I'd recommend the 9924, as it is the included foot print on spin1. I believe the 9924 or 9926 will do the same (or better) signal conditioning than the op-amp conditioner your using. You might want to give it a try, It works specifically well with skipped tooth setups and the function blocks of how it filters are very similar to your opamp circuit. I think spin 1 used the 9924 instead of the 9926 just because. There were some time line constraints, and I think Marco simply picked an option and went with it. I believe we could use the 9926 if we wanted to.
AbeFM wrote:OMG I love this chip.
Looks sweet, do you know where to get it? It didn't show up in my octopart search. I'd like to learn more about it.
AbeFM wrote:5) XOR gate, shortage of parts?
Not sure, but you can probably jumper it out if you have trouble getting it. If not I'd recommend get it while it can be obtained.
AbeFM wrote:6) Peak and Hold Zeners:
Not sure.
AbeFM wrote:8) Fuse Block
Pinch it. The pads are handy for mounting a standard USB connector. The theory on DFH was that this would not have a component populated, and would normally be jumper-ed out via included PCB trace. Such that if one were to short something, the failure point would be in a replaceable area. However that's really a load of bunk, also Marco didn't do it that way, so just ignore it and don't use it. Well don't use it as a fuse that is. I understand it will be removed from future spins.
AbeFM wrote: 9) Stepper Motor Driver
I'm ignorant about these. I'm believe this circuit has not been tested yet, so it may or may not work.
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Re: BOM straightening

Post by nitrousnrg »

1. MOSFETS
What jharvey said. As long it has a logic input, protected and enough current, its fine.

2. EGT
Jared, Abe will change the 5v suuply for a 12v supply coming from a regulator. Abe, the regulator is ok. the driver don't need that much current.

3. MAP
Using a different sensor is up to you, feel free to do it :-) Hardware wise, is pretty much the same, and if you prefer the tip to attach a hose, its perfect. If more people wants that, its going to be the default setup.

4. USB
That one you mentioned is correct (http://search.digikey.com/scripts/DkSea ... ND&x=0&y=0)

Remember to get the cable if you choose to use that connector. A male A - male A cable is very uncommon, if have one around, great.
I use that connector with the cable listed in the BOM.

The other way is to put a mini usb connector (there are cables everywhere) and wire it up to the board, there are pictures of the modifications.

5. XOR:
get them before they ran out of stock! They are difficult to find, at least with those operative temperature ranges. There are a lot of them that works up to 85°C, you'd be fine with one of those too, The regulators won't stand more than 80°C anyway.

6. P&H
zener: this one, for example 2EZ33D5-TP
http://search.digikey.com/scripts/DkSea ... -TPMSCT-ND

7. P&H Darlington
Use the darlington of the datasheet. The driver suggests it, and it has some special characteristics. It needs an Hfe = 1000, Vce its 100V, some capacitance, etc etc. Save yourself from this trouble :-)

8. Dont put any fuse, just bridge the pads

9. STEPPER
you need it? Its pretty much intested

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Re: BOM straightening

Post by Jammi »

Hi, I started a new system to replace the messing with the spreadsheet document.
I also found some suspect issues in the spreadsheet stuff, I documented them in the thread specific to the new system; "FreeBOMBS":
viewtopic.php?f=53&t=1195
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Re: BOM straightening

Post by AbeFM »

Probably won't get to this till tomorrow, buried in other stuff just now. But, the idea is to get the parts list worked out for a "standard" build, which means finding a part number for the usb conector, etc. Not all the questions are for myself, which is why I'm asking some basic ones.

JH: I'm not so sure about this VR chip. I don't think too many people have had luck with it - the key thing in the op-amp circuit is how it rejects short duration (on the timescale of the gate propagation delay) noise. Which for some reason, this car has PILES of.

I guess I should try it, I can always jumper it out later.
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Re: BOM straightening

Post by AbeFM »

So.... I kinda failed to lead any charges here, but..... Do we have enough to make a master list yet?

Jammi, any progress? Anything I can track down for you?

(No luck on the infineon chip here either. Too bad.)
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Re: BOM straightening

Post by Fred »

Not much work has been done on the Puma BOM for some time, we've all been focusing on more important things. I will likely try to spec out the Puma BOM and instructions as I sift through the design with a fine tooth comb on my way to producing Cheetah. Hopefully that will yield a thorough set of instructions and components for entry into the markdown docs and freebombs bom. I'll update this and other threads if/when that starts to come to fruition. I'd *LOVE* to see more people actually using these boards, even if they are soon to be an "old model" - being a custom solution anyway, it makes little difference, just hack whatever to keep up with development, no problem.
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Re: BOM straightening

Post by AbeFM »

As far as getting more people doing software development.... Who's going to work on a system when they don't have one to test? How do you spot your corner cases if you don't have someone running it on the street, reporting what's wrong?

In a way, this highlights the issues with a "universal" design - several have been built, but we can't just use each other's parts lists... because we're doing different things?

Whatever it is... If I can get something put together and working, I'll use it. Otherwise, I'll have to start up with a whole other new ECU for my daily, get buried in that, and not have the time to invest in this project. Since the board's made, it's silly not to get this finished. You might be able to write a lot of cool code for a ENIAC, but you're not going to because you've nothing to test it on - and even if you had functioning code you can't DO anything with it.

And lastly, anything which becomes obvious through the use of the PUMA will absolutely guide the development of the Cheetah. Not getting anything out of a prototype is a waste.
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