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 Post subject: Re: o5e board project
PostPosted: Mon Nov 02, 2015 1:38 pm 
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A 12V indicator is pretty easy and makes it easy to see if the fuse is blown or the wiring is bad. There is a fault light on the system basis chip which would let you know if the voltage dips too low during cranking or from a bad connection. Maybe some other reasons too. This could also be activated by the processor, I guess it sort of becomes a check engine light then.


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 Post subject: Re: o5e board project
PostPosted: Thu Nov 12, 2015 11:24 pm 
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Things have taken longer than I expected the last week or so. In addition to checking the board I have also been making final choices for part numbers and getting ready to generate the bill of materials. A handful of capacitors were able to get reduced from 0805 to 0603. I think I will use ones that have "soft terminations", they are for application where there can be vibration and board flex. When they break they can short, so being conservative here seems like it can be a good idea.

There have been several cycles of submitting the files to the fab shop before getting a clean DFM run. Kicad can be a bit of a challenge it seems. I think Advanced Circuits will do a good job and they are being patient with my questions. Their quote looks several dollars above the places doing this work off shore, but I'll be able to claim it was made domestically and maybe that will help make a good impression.


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 Post subject: Re: o5e board project
PostPosted: Mon Nov 16, 2015 12:24 am 
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We're down to last minute changes now. In reviewing the chip manual I found we can enable auto baud rate detection for booting from the serial line, so I've added a resister to configure this.

I am considering 2 last minute changes that are not electrical, just basically mechanical. I'm asking for opinions on the changes. One is to add about 1/4" to the length of the board so that the mounting holes have more clearance. They look tight in the two corners near the 40 pin analog connector. Here's a picture with a 1mm grid showing.

The other change would be to add 1/8" to the top and bottom edges to fit a different enclosure. I would like an enclosure that does a good job but also has a nice feel and makes a good impression. Here are the 2 current choices, they are both tube extrusions which would get end plates.

This is one idea from Chinese enclosure company. http://yonggu-enclosure.en.alibaba.com/product/1881203687-218811921/97_40_5_130L_mm_aluminium_extrusion_housing_for_high_technical_quality.html

The other idea would be a stock 6063 aluminum extrusion like this one. https://www.onlinemetals.com/merchant.cfm?pid=14966&step=4&showunits=inches&id=1269&top_cat=60

The heavy duty standard extrusion is 1/8" wall which would feel pretty solid. It would cost a good bit more, $10 a box plus maybe more to machine. This heavier enclosure would require me to add the 1/8" to the sides of the current board, I would do that without any other changes.


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 Post subject: Re: o5e board project
PostPosted: Mon Nov 16, 2015 12:12 pm 
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My vote is for the actual case. It's strong, light and designed to do what you want to do at a good price. The other path is way heavier than required and probably 10x - 20x the cost by the tin you have a usable case.

I think you forgot to attach the pic of the connector???


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 Post subject: Re: o5e board project
PostPosted: Mon Nov 16, 2015 12:49 pm 
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Horizenjob wrote:

Min qty 100, is not this an issue?

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 Post subject: Re: o5e board project
PostPosted: Mon Nov 16, 2015 2:30 pm 
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Quote:
Min qty 100, is not this an issue?


I don't know yet. Their website is full of testimonials from people that bought just a few units. I need at least one to check the fit of the board and see what it will take to hold it in place. Then I would buy 10 and then 100.

I didn't think the box made from stock would be 10x more, but it wouldn't be sand blasted or anodized etc. either. I'll make enquiries about the unit above and get that ball rolling.

Quote:
I think you forgot to attach the pic of the connector???


Not sure what you mean. Were we are now is a 40 pin ribbon cable for the analog side of the box. This just goes onto header pins. The driver board and power supply will just have wire pigtails. At this point I don't know what to do that's better. I expect a person would get connectors that go to the next level of the wiring harness from a junkyard and then splice in the new wires.

I'm open to better ideas, but near term I want to be able to prove this is a viable ECU and get to work on software for it. The people I have lined up for first units will be able to deal with this.

Maybe the production units would have a case a few centimeters longer with a bulkhead connector on the end plate. Then the pigtail would solder to that and their could be different end plate pieces with different connectors to match different cars?


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 Post subject: Re: o5e board project
PostPosted: Mon Nov 16, 2015 3:06 pm 
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Horizenjob wrote:
mk e wrote:

I think you forgot to attach the pic of the connector???


Not sure what you mean. Were we are now is a 40 pin ribbon cable for the analog side of the box. This just goes onto header pins. The driver board and power supply will just have wire pigtails. At this point I don't know what to do that's better. I expect a person would get connectors that go to the next level of the wiring harness from a junkyard and then splice in the new wires.

I'm open to better ideas, but near term I want to be able to prove this is a viable ECU and get to work on software for it. The people I have lined up for first units will be able to deal with this.

Maybe the production units would have a case a few centimeters longer with a bulkhead connector on the end plate. Then the pigtail would solder to that and their could be different end plate pieces with different connectors to match different cars?


Horizenjob wrote:
Here's a picture with a 1mm grid showing.


I just didn't see a pic.

A pigtail solution is really not going to work for anything but prototyping so understanding where you're heading will be pretty important in selecting the enclosure I think.

If we are just talking prototypes with a pigtail for wiring then anything the board will fit in is probably a fine choice....something simple and in stock at one of the major suppliers would be best I think...but by not solving the connector question up front you run the risk of scrapping board tooling when the final call is made. Just keep that in mind.


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 Post subject: Re: o5e board project
PostPosted: Mon Nov 16, 2015 9:10 pm 
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Ford EEC-IV 60 pin.
Should be enough measurements to lay out in KiCad, or I have it in Eagle.

Attachment:
connector6.png
connector6.png [ 4.98 KiB | Viewed 14321 times ]

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 Post subject: Re: o5e board project
PostPosted: Mon Nov 16, 2015 10:47 pm 
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Quote:
I just didn't see a pic.

Ah, that picture. I must have a short attention span :-)

Here you go....


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 Post subject: Re: o5e board project
PostPosted: Tue Nov 17, 2015 12:06 am 
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Quote:
but by not solving the connector question up front you run the risk of scrapping board tooling when the final call is made. Just keep that in mind.


I guess I don't feel I know how to solve the connector problem yet. I think the pigtail would work for me and at least the first people I have in mind for a unit. These are all basically formula or track cars.

What do you guys picture, some generic connector that comes with a pigtail? I can see trying to match an OEM harness, but that starts to become difficult and I don't feel tied into any one motor or manufacturer.

I am not really happy with the tin plated auto connectors, but the alternatives seem to get expensive pretty quickly.


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 Post subject: Re: o5e board project
PostPosted: Tue Nov 17, 2015 2:17 pm 
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Horizenjob wrote:

What do you guys picture, some generic connector that comes with a pigtail?



A generic connector is the standard answer. Then separately you buy a mating kit, or a pigtail or harness.

I guess there is nothing really wrong wrong with a wires coming out of the box but it is either time consuming or expensive depending on who's doing the work, there is no way to seal the unit, and it's hard to be sure the wires aren't being pulled/flexed at the solder joint which tends to lead to reliability issues.


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 Post subject: Re: o5e board project
PostPosted: Tue Nov 17, 2015 3:39 pm 
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OK, I agree with everything you're saying here.

I will keep two paths open for maybe a couple of days before submitting the board order.

One path goes the way we are going now and mitigation for the issues you mention is designing some strain relief into the end plates and possibly potting the wire exits with some compound like silicone or urethane adhesive. The potting compound could seal for moisture and also be strain relief.

In either case we can look towards some type of connector. An issue here is that at the moment the board design is oriented towards having the power lines coming out one side and the analog out the other side and that the unit consists of 2 boards. The sockets would go on the narrow end of the boards, so they are not wide enough for the 60 pin EEC-IV socket shown above. At the moment the cards are 69 mm wide.

Until we redo the boards into one unit we can't use the cases with the big connectors on the side. Possibly we could use ~40 pin auto connectors on the ends. If we identify a way to go forward like this I can put that connector in for the first proto boards in the next couple of days.


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 Post subject: Re: o5e board project
PostPosted: Tue Nov 17, 2015 6:02 pm 
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There are also Ampseal header / connectors with various pin counts; the Ampseal 35 is used on the little microsquirt.

Deutsch offers connectors of various configurations as well, some of which are like bulkhead connectors and wire to the board.

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 Post subject: Re: o5e board project
PostPosted: Wed Nov 18, 2015 1:01 am 
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I spent some time looking at the connectors again and now remember some of the issues.

One big difficulty is the ignition coil wires. They need to be able to handle peak currents of over 10 amps and voltage spikes to 350V - 450V. This is a downside to having the coil drivers in the box. I noticed that one of the competitors sells a coil driver unit that uses a pigtail, so maybe it's a common problem for those wires.

I am liking the Deutsche D369 units. They cost around $30 for a pair of 9 pin connectors. That's without the pins. These would work for analog and fuel injectors maybe.

I saw some nice ECU style connectors with 76 pins, implemented as a 40 pin and a 36 pin section. The board side though seemed only available in the pair of units together, not separate 40 and 36 pin units I could install at opposite ends of the box.


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 Post subject: Re: o5e board project
PostPosted: Mon Dec 21, 2015 2:58 am 
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Decided on a slightly larger box, so the board is now 133 mm x 85mm ( 5.25" x 3.4" ).

There was a good deal of going back and forth with the board fabricator. There were some minor changes needed for clearances and learning how to use their website. I am having the board fabricated by Advanced Circuits. They have been unreservedly helpful, patient and encouraging in this process.

In the end the big issue came down to understanding wether the different layers of the Gerber file were positive and negative images and wether they should be declared as positive or negative when they were submitted. It turned out that specifying "negative" meant that they would negate the image, not that the image was negative to begin with.

Long story short, the first 10 boards have been ordered. Now I'm ordering parts and preparing the information for the assembly.

The driver board layout is mostly finished now too. It is getting some double checking and cleanup. Today I added a trace to allow measuring injector current. I hope that will allow measurement of injector dead time. Now I'm looking at being able to measure coil current with the ADC on the CPU. The coil pre-drvier chips already do a coarse measurement of coil current, but it might be nice to have something like a scope picture... These things are to help with setup of the unit.


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 Post subject: Re: o5e board project
PostPosted: Mon Dec 21, 2015 8:02 am 
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Great news! Any idea of a timeline for the HW project?


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 Post subject: Re: o5e board project
PostPosted: Mon Dec 21, 2015 1:01 pm 
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Horizenjob wrote:
Long story short, the first 10 boards have been ordered. Now I'm ordering parts and preparing the information for the assembly.

Congratulations on your big day!

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 Post subject: Re: o5e board project
PostPosted: Mon Dec 21, 2015 1:10 pm 
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Things should progress a little quicker now, I had thought submitting the job for fabrication would go rapidly but it didn't.

The way this fab house works is there are several routes you can take. They offer "full spec", "standard spec" and "custom spec" boards. Our production boards will likely be custom spec so that we can have them exactly the way we want them. That would include items like gold plating, thicker copper layers, higher TG temperature of the fiberglass and possibly thicker copper plating for vias and negative etchback also.

For these boards I selected standard spec, which gives a faster delivery time, 5 days in this case. It also avoids a several hundred dollar tooling charge, which is waived when re-ordering the board in custom spec.

I ordered 10 boards because it cost hardly any more than 5 boards...


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 Post subject: Re: o5e board project
PostPosted: Mon Dec 21, 2015 1:17 pm 
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Quote:
Congratulations on your big day!


Thanks. Andrey, all this time I have pictured you living in Russia, but now I see you are in NJ. That's just down the road from me, what exit are you at? :-)


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 Post subject: Re: o5e board project
PostPosted: Mon Dec 21, 2015 4:48 pm 
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Horizenjob wrote:
That's just down the road from me, what exit are you at? :-)


https://turnpikeinfo.com/view-exit.php?state=new-jersey&road_name=new-jersey-turnpike&key=15W

:)

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 Post subject: Re: o5e board project
PostPosted: Tue Dec 22, 2015 12:31 am 
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Andrey
I am curious what you folks consider to be your favorite coil drivers. I remember one being mentioned. Also what your favorite DPAK package driver is.

Have you folks found any really high clamp voltage units, like 800V?


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 Post subject: Re: o5e board project
PostPosted: Sun Dec 27, 2015 7:29 pm 
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Horizenjob wrote:
Andrey
I am curious what you folks consider to be your favorite coil drivers. I remember one being mentioned. Also what your favorite DPAK package driver is.

Have you folks found any really high clamp voltage units, like 800V?

There are IGBT's that can clamp over 1200V; MOSFETs have only recently been getting up to that range.

Good luck.

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 Post subject: Re: o5e board project
PostPosted: Tue Jan 05, 2016 4:24 pm 
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My boards came in today from fab at Advanced Circuits. They look to be very well made. I'll drag out a microscope for a closer check later. I'm going thru the BOM now and double checking it, then will place orders for parts and ship these back to Advanced Circuits for assembly.

One thing I notice is that because of their small size the boards are quite stiff and they are also mounted on their long side. I had planned on using flexible terminal SMT caps to make the boards vibration resistant - but that might not be needed. Perhaps it's worth doing on the largest caps, I have one 1210 and just a few 0805.


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 Post subject: Re: o5e board project
PostPosted: Wed Jan 06, 2016 9:05 am 
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Fancy!

Is the plan to manually check everything before sending them back for assembly?


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 Post subject: Re: o5e board project
PostPosted: Wed Jan 06, 2016 1:53 pm 
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Basically that's the idea. Checking the board to see it was made the way I expect. I don't it deviates from the schematic, but my understanding of something might deviate from reality.

I have found 2 small flaws. One is that shiny rectangle on the lower left of the board. It's the ground pad for the system basis chip. It should be square because the top and bottom areas should be covered in soldermask and the center should have a "#" type shape also of soldermask to prevent solder from flowing down those thermal vias that connect to the ground plane. They can fix this, but in production it needs to be right or the special handling would cost something.

The other issue is that there are fiducial markings that the assembly robot uses for location. One of these has a slight imperfection, it includes a bit of the guard trace which circles the outside of the board. I thought that the fiducial would have a priority and the guard trace would have a slight dent, but it went the other way and I need to figure it out. I believe they can teach that to the mention, but again you would want to fix it for production, just because you want to know how to drive the tool properly.

I'll try to get some closer up pictures of the board.


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