DFH - Defacto FreeEMS Hardware in KICAD

[Fred]

Well said Delta, thanks for piping up :-)

I do think we should supply a vendor option to help fill in any blanks that might be left out.

OK, that is a valid point, however what the man above said still applies. I was thinking of saying something about end of lines etc too, but hadn't got around to it. Better from someone elses lips anyway, I do far too much typing as it is. If you insist on putting something in anyway, select the vendor with the best website and use them as a cross reference against the description. I still don't think you should include more than one though and I'll explain why shortly.

I don't see why everyone should have to create their own order BOM just because we can't make one BOM to fit them all.

Everyone won't. For a start, the BOM is only relevant to a produced board. When a board design is finalised that is the time to create a BOM for the board. If you include part numbers along the way then the maintenance issue of looking up each new components part number as you grow and change the design would be tedious and somewhat pointless too. I mean, we've barely gotten started and values have been changing left right and centre. Finally, once that initial BOM with descriptions etc is produced at board finalisation time, one of us from each region can create an xls/ods/text/html/etc vendor BOM and I can upload them all to the main website such that everyone can easily place their order locally. I don't see why it should be inside the schem and as Delta pointed out there are quite a few reasons to specifically not do that.

I also think 4 fields will allow us to cover the non vendor specific info.

How can you be sure? It seems like limiting yourself to me. resistor, MF, 1%, 1/4w package, 1/2w dissipation, inductance less than X, capacitance less than Y and we are at 7. Probably we don't need that detail, but why cut yourself off.

When you tell KICAD to export a BOM you can select what you want exported, so someone from a remote island in Africa, can print it with fields 1,2,3,4 but for me I can print it with fields 5. What ever allows you to get'er done.

As I said, there will be a page or more than one page about this board when it's ready and all the information can live there and be maintained separately to the schem. Once the schem is nailed down it should stay fixed at least until some testing is done IMO. I know one member of this site that has only posted a few times thinks differently to that, but I don't think it makes sense to change more things until you know what is wrong with what you have.

I forsee a discussion on the smd/th combined board in the future. I still think it's a good idea, but there may be some issues that I can't see that someone else will bring up shortly.

Fred.

[Fred]

P&H discussion :

http://www.diyefi.org/forum/viewtopic.php?f=9&t=378

Over voltage and reverse polarity discussion :

http://www.diyefi.org/forum/viewtopic.php?f=9&t=377

[jharvey]

R1 100ohm 1% Metal Film 1/4W
D1 1N4004 Power Diode

I guess I don't understand why we can't do it like this.

R1 100ohm 1% Metal Film 1/4W 100XBK-ND 97K4944
D1 1N4004 Power Diode 1N4004GDICT-ND 42K2822

or perhaps like this

R1 100ohm 1% Metal Film 1/4W "digi 100XBK-ND" "newark 97K4944"
D1 1N4004 Power Diode "digi 1N4004GDICT-ND" "newark 42K2822"

If you don't want the vendor's listed, you don't have to list them when you make your BOM.

Means that an alternative part can be sourced easily - all the info you need is there. Any competent engineer will know whats going on and be able to help.

Any competent engineer will know that you can't get a resistor by specifing 100ohm 1% Metal Film, you also need axial vs SMD, cut tape vs individaul, temp coefficient, % +/- vs %+ or %-, ect. Most of that stuff we don't care to spec however. Listing a part number fills in some of those blanks by default, and it's not like I'm saying you have to use that vendor. You can sub if you want.

[jharvey]

When a board design is finalised that is the time to create a BOM for the board.

I don't see how you can layout a board with out knowing what footprints you need. I think the BOM has to happen when you go from schematic to PCB.

Also I typically don't go several clicks to find that data, I typical open the file in emacs, then edit the text in the file. Lot easier to do it that way, and you can do an entire schematic at once. The file format is quite straight forward, and one of the reasons why I like the open-source versions more then the private soft.

[jharvey]

Here yet another release A.10

https://sourceforge.net/project/showfil ... _id=619128

see change log and todo list included w/ this release, changes this time were fairly minor. I think next weekend will produce more significant changes.

[Delta]

R1 100ohm 1% Metal Film 1/4W
D1 1N4004 Power Diode

I guess I don't understand why we can't do it like this.

R1 100ohm 1% Metal Film 1/4W 100XBK-ND 97K4944
D1 1N4004 Power Diode 1N4004GDICT-ND 42K2822

or perhaps like this

R1 100ohm 1% Metal Film 1/4W "digi 100XBK-ND" "newark 97K4944"
D1 1N4004 Power Diode "digi 1N4004GDICT-ND" "newark 42K2822"

If you don't want the vendor's listed, you don't have to list them when you make your BOM.

Means that an alternative part can be sourced easily - all the info you need is there. Any competent engineer will know whats going on and be able to help.

Any competent engineer will know that you can't get a resistor by specifing 100ohm 1% Metal Film, you also need axial vs SMD, cut tape vs individaul, temp coefficient, % +/- vs %+ or %-, ect. Most of that stuff we don't care to spec however. Listing a part number fills in some of those blanks by default, and it's not like I'm saying you have to use that vendor. You can sub if you want.

A systems engineer producing a layout for full scale production needs to know cut tape/individual - but its completely useless to an end user building one board. none of our specs are tight enough to require %+- etc. Just a tolerance is fine. Temp coefficient/derating is only really useful for devices that you'de have a full part number for, so they can just look up the part. eg
M1 VND5N07 TO-220
so they could easily spec a replacement part that suits.

Axial/smd is completely evident from the layout but I was assuming the first board layout would be one or the other or have provision for both - so its not necessary at all for the first board - besides most resistors are listed by type anyway in most BOMs. Fair enough though, add SMD/Axial

Show me a design that needs the rest of these things for a single user build at the frequencies/in the applications were talking about?? Its just not necessary for a low volume design. If your planning on running 10000 boards in a high frequency or ultra high precision environment, then yeah ok, but most systems engineers will create a BOM of their own which sources parts from their own stocks or from their cheapest suppliers anyway, and only use your BOM as a guide.

By all means put a part number in to indicate what part you designed the pads/footprints for but you will find not many people will use it for personal builds.

[AbeFM]

re: part numbers:
Goodness me! I've gone back and forth on this thing about 50 times, both sides make some good points.
I think in the end if the guy doing the design wants to put them in, you can certainly ignore what's there easier than what isn't there. And if you change a component, leave the unused 20 ohm resistor in the BOM, with quantity 0.

Certainly you'd have to include many things about the footprint, and I sort of like having the SMD and the TH versions in there. But, as an end user - as long as there IS a BOM at some point, I don't care how it was made. Certainly I don't want to be tied to digikey to get the bare minimum information to order it... but my feeling is, at least if there is ONE complete BOM, a totaly hard up person could just order it from overseas and pay the shipping, and know it'll work.

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Ok, I'll multipost to seperate topics.

[AbeFM]

As Fred alluded to, I'm really against this priming the injector thing. I don't see any advantage. Is it just so you can run injectors 87% duty cycle instead of 85%? There are so many reasons it hurts you, and so little to gain, reclaim the board space, and skip it. Unless someone has some really good reason for it.... It almost seems that as battery voltage wandered you'd need to scale that value anyway. There's just a lot of downsides. I don't think it's a great idea, especially where there are better things to integrate onto the board.

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I believe a dead injector will look different than one which is working - o-scoping them opening you certainly get something other than a R-L current. You can see the area where the pintle moves, and you can tell when it stops.

If we were doing PWM low-ohm driving, I would say it's a must - it would allow you to autotune this parameter, and I really like it. With a driver chip, I'm not sure we need it.
Then again, the driver chips do need some componant selection - and monitoring that heel in the curve would certainly help with that. All those things like voltage compensation would be a no-brainer - and this whole holding current thing would be off the table - if you could reliably add this in. What I don't know is if the CPU would be able to keep track of all that, is it too fast?

[AbeFM]

You could even do that with solder jumpers if you want it compact and without holes.

Capacitive coupling? Ok, so this is probably not a concern with what we're working on. Still, one way to do this (I don't know how it drives expense) is to put footprints compatible with 0-ohm SMD resisitors. We have lots of these here at work (rather, we use them often in designs) as a reliable way to bridge gaps. And you could bridge those with solder (or bits of wire) too, but at least is leaves the option. TH doesn't bother me, just depends if it starts to drive the design.

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LED's to ouput drivers, perhaps RPM input signal as well

Ok, that's awesome. Before the chip, after the electronics. I sure hope this board supports VR *AND* digital ins (such as my mazda-copied circuit). Doesn't take much space, and looks the same to the CPU, makes it MUCH more flexible and prevents boards which look like mine.

I spent so much time with an oscope in there, trying to figure out what was being SEEN by the CPU, and by the circuit, that would be a huge help. Ground a line, look for a response. That simple.

Best of all, one can substitute a test point for the LED, and THAT is of nearly infinite value. I'm a huge fan of test points, it's easier to tell other people where to look (check voltage on TP17), and easier to get to stuff with a probe if you have them.

I'm hoping to get the schematic open in kicad tonight or tomorrow... I really love to see this going forward and I really want to see the "hall effect" dual op-emp input put in here.

[Fred]

What I don't know is if the CPU would be able to keep track of all that, is it too fast?

No way, that's right up there with ion sensing etc, just way out of what we even want to achieve. If you are fitting together a random system you should DESIGN it and PROGRAM it not rely on the system to figure out WTF you have done with it. IE, measure or reference the specs and setup the hardware to match that. You guys really ought to take some software design classes :-p You have to make reasonable assumptions when you enter into a design and base your work on that. Functioning injectors is a reasonable assumption in anyones books. The driver chips for P&H if we were to do that take care of sensing the current and sorting it out themselves. The only thing the ECU needs to know is how much of the full pulse is NOT flowing fuel. That's all. Nothing else.

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