[info] Prometheus - NEW compact ECU shield!

Hardware inside and outside of the ECU
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andreika
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Prometheus - NEW compact ECU shield!

Post by andreika »

Hi there!

Let me introduce our new ECU board - Prometheus!

About Prometheus...
The project is born as a lightweight alternative for a transition from SECU-3i EFI to a more powerful and innovative hardware platform.
The idea is simple: take the existing SECU-3i housing and make a replacement of those two boards with one small PCB of the equal size.
And try to put inside everyting needed for a 4-cylinder fuel injection engine, including ready-to-use ignition drivers and even a bit more ;)
The PCB is self inclusive, there is no need for STM32Discovery brain boards, external modules etc.

DISCLAIMER:
1. Prometheus board is an experimental hobby project. It's an independent design, not associated with the authors of rusEFI, but using rusEFI under the license. Please use only official rusEFI boards to avoid any problems - Frankenso, Frankenstein etc.
2. We're NOT experts in electronics or EFI, and we can NOT guarantee the operation of this board or correctness of the documentation. We are not liable for any damage caused by them.
3. The board is NOT universal, and has been designed for the limited specs of an "ordinary" 4-cylinder engine. We've made it for our own needs. It cannot do everything that official rusEFI boards do, and it's certainly NOT a complete replacement of them. See item 1.
4. The whole idea of 'Prometheus' project was to stuff "everything and the kitchen sink" densely into one small board, without any additional boards needed. It's a reckless experiment, for sure. But we never give up! 8-)
5. The current board revision was developed for manual pcb assembly only (no thermal relief requirements satisfied and so on), and for components available in our region, also taking into account the compatibility with SECU-3i peripherals.

Licensed under the TAPR Open Hardware License (http://www.tapr.org/OHL).

Special thanks to @Russian and @Kb1gtt for their brilliant work and inspiration!
Prometheus assembled board rev.0.1
Prometheus assembled board rev.0.1
prometheus-top-and-bottom.jpg (340.11 KiB) Viewed 43225 times

Specs:
  • * The newest STM32F469VI (freq 180 MHz, RAM 384 kB, 2 MB flash) in LQFP-100 package!
    * Also there's an alternative: more affordable and cheaper STM32F405RG on the same board (double footprint!), not functionally constrained! (the package is only 64 pins - all pins are used!)
    * MAX9926 - VR controller for crankshaft & camshaft
    * TPIC8101 - knock sensor (detonation) controller
    * DRV8825 - step motor controller for IAC (you can populate the IC or a fabricated Pololu module)
    * CP2102 - cheap USB controller with ADUM1201 for electrical isolation
    * SN65HVD230 - CAN-bus controller
    * CJ125 - wideband oxygen sensor controller (highly experimental function!)
    * VND14NV04 - onboard 4-channel protected injection drivers (high-impedance).
    * BIP373 - onboard 4-channel "smart" protected ignition drivers. Direct drive of ignition coils!
    * Analog sensor inputs for: MAP/MAF, IAT, CLT, TPS, oxygen sensor
    * Low-side power protected outputs (including inductive loads): power relay, fuelpump, fan, starter block, oxygen sensor heater relays
    * Protected signal outputs: Tachometer, CheckEngine, and also two additional signal inputs & two outputs
    * Additional analog sensor input and ignition voltage measuring/detection input
    * Bluetooth module HC-06 onboard (both SMD and TH versions supported)
    * MicroSD memory card slot onboard
    * Switching DC-DC 5V power supply onboard
    * CR2032 holder for backup battery supply
    * And all this fits the compact 4-layer PCB smaller than 93 x 100 mm!
Additional info:
  • * There's no multi-pin connector on board, all pads are just for direct harness soldering.
    * Two sided pcb assembly!
    * All resistors and capacitors are not less than 0805.
    * You'll need an external programmer (ST-LINK/V2 mini) for firmware update.
    (more to come)
All project documentation (including schematics & gerbers) is available below.
More photos and description will follow.
Stay tuned!


Thank you for your attention,
andreika.
Last edited by andreika on Wed Aug 30, 2017 4:29 pm, edited 6 times in total.
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Re: Prometheus - NEW compact ECU shield!

Post by andreika »

Current board revision is rev.0.2 (2018-01-30) (not fabricated, under development)
For earlier fabricated revision (rev.0.1), see Full documentation for old rev.0.1 (2017-04-07).

Latest Prometheus schematic:
Schematic diagram, rev.0.2 (2018-01-30)

Latest Prometheus gerber files:
Gerber files, rev.0.2 (2018-01-30)


Prometheus wiring diagram:
(2017-04-24)
(2017-04-24)
prometheus-wiring-diagram.png (4.78 MiB) Viewed 43662 times
Bill of materials:

Download BOM in PDF Format
Download BOM in Excel XLS Format

Interactive Assembly/BOM Map (test version for rev.0.1):

https://rawgit.com/andreika-git/prometheus/master/html/prometheus-map.html

* * *
Last edited by andreika on Tue Jan 30, 2018 12:13 pm, edited 4 times in total.
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Re: Prometheus - NEW compact ECU shield!

Post by andreika »

This message is reserved for additional project info & files.
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Re: Prometheus - NEW compact ECU shield!

Post by andreika »

Some more pics of Prometheus PCB rev.0.1 (2017-04-07):

Schematic diagram, Page 1:
Page 1, Rev.0.010 (2017-04-07)
Page 1, Rev.0.010 (2017-04-07)
prometheus-schematic_1.png (908.01 KiB) Viewed 43389 times
Schematic diagram, Page 2:
Page 2, Rev.0.010 (2017-04-07)
Page 2, Rev.0.010 (2017-04-07)
prometheus-schematic_2.png (155.46 KiB) Viewed 43389 times
(See full schematics here)

Board assembly example:
Board assembly example, Rev.0.010 (2017-04-07)
Board assembly example, Rev.0.010 (2017-04-07)
pcb-almost-all.jpg (1.96 MiB) Viewed 43389 times
PCB Layers View:
PCB Layers View, Rev.0.010 (2017-04-07)
PCB Layers View, Rev.0.010 (2017-04-07)
prometheus-pcb-layers.png (282.14 KiB) Viewed 43389 times
3D rendered view (top side):
3D rendered view (top)
3D rendered view (top)
prometheus-pcb-3d-top.jpg (379.39 KiB) Viewed 43225 times
3D rendered view (bottom side):
3D rendered view (bottom)
3D rendered view (bottom)
prometheus-pcb-3d-bottom.jpg (310.61 KiB) Viewed 44036 times
Last edited by andreika on Tue Jun 06, 2017 7:09 pm, edited 2 times in total.
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Re: Prometheus - NEW compact ECU shield!

Post by AndreyB »

Subscribed!

Sweet renders, what are your fabrication plans?

Will I get a board? Pretty please :)
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Re: Prometheus - NEW compact ECU shield!

Post by mobyfab »

Very cool!

This is a lot more like what I am looking for, you got me interested :)
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Re: Prometheus - NEW compact ECU shield!

Post by kb1gtt »

Yes very cool. I look forward see seeing more. Keep up the great work.
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Re: Prometheus - NEW compact ECU shield!

Post by andreika »

Thank you all for your kind words!
russian wrote:Sweet renders, what are your fabrication plans?
Will I get a board? Pretty please :)
Sure, I'll send you a couple! :) I plan to finish the first board in a month, with some luck.
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Re: Prometheus - NEW compact ECU shield!

Post by kb1gtt »

Have you see my suggested design environment, and other such design related items. If not here's some links
http://rusefi.com/wiki/index.php?title=Manual:Hardware
http://rusefi.com/wiki/index.php?title=Manual:Hardware:PCB_design_rules

The Maxim article is quote an interesting read. Especially this graphic which shows how currents flow on the ground plane starting at about 1kHz and above.
5450Fig10.gif
5450Fig10.gif (74.16 KiB) Viewed 44010 times
I spend more time placing chips and keeping track of current loops than anything else in a design. That Maxim article has many interesting points.

If you would like a review either privately or publicly, feel free to get me something to review and I can comment.

Is that done in Altium? I have Eagle and Kicad, and some old copies of OrCAD, but I do not currently have access to Altium. So I may be limited in what I can offer in terms of a review.
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Re: Prometheus - NEW compact ECU shield!

Post by AndreyB »

Yes Altium Designer. Rumors on http://rusefi.com/slack hardware channel are that gerbers were already sent to a fab shop!
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Re: Prometheus - NEW compact ECU shield!

Post by andreika »

kb1gtt wrote:Have you see my suggested design environment, and other such design related items. If not here's some links
I spend more time placing chips and keeping track of current loops than anything else in a design. That Maxim article has many interesting points.
Thank you for the information!
I've used 10/10 traces, and yet it was extremely hard to fit everything on such a small pcb... Adhering to the strict design rules and perfect grounding would have made it nearly impossible, I guess... As for the rest, it's pretty compliant. At least I did my best, in spite of spending merely a week on this design... :oops: As they say, don't try this at home! :lol:
kb1gtt wrote:If you would like a review either privately or publicly, feel free to get me something to review and I can comment.
Is that done in Altium? I have Eagle and Kicad, and some old copies of OrCAD, but I do not currently have access to Altium. So I may be limited in what I can offer in terms of a review.
Yes, it's Altium. I'd like to assemble it first and see what's happening. It's like the first pancake, after all! And then I'll share all the documentation.
I've seen an Altium-Kicad exporter somewhere, so I hope it won't be a problem. And thank you, I would appreciate your help in a potential predicament. I'll keep you posted!
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Re: Prometheus - NEW compact ECU shield!

Post by kb1gtt »

I understand the desire to not post wrong information. There seems to always be some issues on the first build. I typically feel sheepish on my first spin mistakes. At work I made a fairly simple board, which had a 555 timer, a relay and some connectors. I got one header 180 wrong, which put all the connections on the wrong side, and a resistor which caused it to blink fast. Ooops. Any how those are things that commonly get caught by a second set of eyes, which I don't have at work. I offer the public and private review, such that I can help avoid first spin issues.

Also if you haven't already done it, another thing I do which helps avoid those first spin issues, is to print 1:1 scale on a piece of paper. I then use a set of calipers to verify that the X and Y dimensions measure properly. The I place each chip on the board and verify that it fits on the pads as expected. Paper is much lower cost and faster to prototype with than waiting for PCB spin.

Your 3D is ooh la la. Some day I need to get around to doing the 3D for Frankenso.

Any how, good work and keep it up. If you want to bunch something off of me, feel free to inquire.
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Re: Prometheus - NEW compact ECU shield!

Post by matt »

andreika wrote:Hi there!

Let me introduce our new ECU board - Prometheus!

About Prometheus...
The project is born as a lightweight alternative for a transition from SECU-3i EFI to a more powerful and innovative hardware platform.
your SECU-3 logo remind me to someone called Juan on speeduino forum.
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Re: Prometheus - NEW compact ECU shield!

Post by AndreyB »

matt wrote: your SECU-3 logo remind me to someone called Juan on speeduino forum.
See http://rusefi.com/forum/viewtopic.php?f=13&t=1179 for the saga of Juan stealing from SECU-3.
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Re: Prometheus - NEW compact ECU shield!

Post by matt »

yes. i know that. got reading about this in the end of 2016 at speeduino forum
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Re: Prometheus - NEW compact ECU shield!

Post by matt »

russian wrote: See http://rusefi.com/forum/viewtopic.php?f=13&t=1179 for the saga of Juan stealing from SECU-3.
i wonder what is meaning of saga. tried at google translate, no result.
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Re: Prometheus - NEW compact ECU shield!

Post by andreika »

kb1gtt wrote:those vertical thru hole components were the injector chips. I guess those must be the ignition chips.
Those vertical thru hole ones are Bosch BIP373 - "smart" ignition chips, and they come only in TO-220 package. And I think that's for the better, as we use an aluminium housing as a heat sink, and also less interference. Well, in fact, they're not original Bosch, but Chineese clones ("30115" chip). Nevertheless, they work extremely well! ;)

Here they are on my old SECU-3i board:
Warning! It is crucial to use mica insulators on all BIP373's to avoid short circuiting to the housing!
bip373_on_secu3i.jpg
bip373_on_secu3i.jpg (113.84 KiB) Viewed 43968 times
(Unsoldered on the left, and already attached to the housing on the right).
Last edited by andreika on Fri Apr 14, 2017 11:19 pm, edited 2 times in total.
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Re: Prometheus - NEW compact ECU shield!

Post by klyttle »

Excellent! A board this size would be closer to ideal for use in space-constrained applications, such as 2-wheeled and small 4-wheeled vehicles.

I had a look at that SECU-3i enclosure, and it looks to be rather tall, though; one might have a challenge finding a suitable spot on some 2-wheelers for it.

But still, I really like your new baby! :)
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Re: Prometheus - NEW compact ECU shield!

Post by andreika »

klyttle wrote:I had a look at that SECU-3i enclosure, and it looks to be rather tall, though; one might have a challenge finding a suitable spot on some 2-wheelers for it.
Yeah, because it had two boards stacked one under another. My colleague @darxfame has the same 'height' problem too and is in search of the smaller housing... You might look at cheap Gainta enclosures, if they are in your local stores...
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Re: Prometheus - NEW compact ECU shield!

Post by AndreyB »

matt wrote:i wonder what is meaning of saga.
"saga" meanss a long detailed account, story
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Re: Prometheus - NEW compact ECU shield!

Post by kb1gtt »

The primary side of the coil is commonly 350V to 450V. I try to plan for at least 500V. If there is exposed metal in air, you probably want to consider creapage and clearances. KICAD includes a PCB calculator, snippet below for 500V.
Untitled.png
Untitled.png (52.29 KiB) Viewed 43956 times
SaturnPCB seems to suggest 98mil PCB materiel.
Untitled2.png
Untitled2.png (174 KiB) Viewed 43956 times
If you do not, or can not, satisfy these setbacks, you might want to consider using some hot snot, or perhaps silicon caulking to prevent stray voltage issues. Small changes in humidity can cause un-desirable issues.
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Re: Prometheus - NEW compact ECU shield!

Post by mobyfab »

Isn't it more around 100-150V? On coil sticks at least.
Also, can we use proper units? ;)

Maybe he can use slots to increase creapage distance. (like some power supplies)
I don't think commercial ECUs are using any fancy systems for protection other than conformal coating.
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Re: Prometheus - NEW compact ECU shield!

Post by andreika »

kb1gtt wrote:SaturnPCB seems to suggest 98mil PCB materiel.
Yes, I've used SaturnPCB and I know recommended clearances. And I ignored them! :) I'll tell you why (I'll use metric system, sorry).

1. Do you know the smallest clearance of TO-220 package used in BIP373?
TO-220-clearance.png
TO-220-clearance.png (8.32 KiB) Viewed 43951 times
It's 1.2 mm (measured on a real part!), i.e. less than 50 mil. Needless to say that BIP373 is a specialized chip for coil ignition.

2. I've exposed only narrow central parts of ignition traces:
ignition-trace-clearance.png
ignition-trace-clearance.png (7.5 KiB) Viewed 43951 times
The min.clearance is 1.6 mm (63 mil). The coated (non-exposed) clearance is 1.0 mm. For internal layers, the clearance is even smaller, but it complies to recommended values.

3. The same design was used in the working SECU-3i board:
ignition-trace-clearance-secu3i.jpg
ignition-trace-clearance-secu3i.jpg (56.5 KiB) Viewed 43951 times
And everything runs just fine!

4. My ECU is located under the hood. That's why I use urethane coating for all my pcbs, and it's mandatory, I think!
Image

But I agree that this problem is essential and should be considered, thank you!
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Re: Prometheus - NEW compact ECU shield!

Post by kb1gtt »

All the pencil coil's I've seen have been fully potted, as well pretty much any modern ECU I've seen has been fully potted. Coatings certainly offer a better insulation than air gaps. Also keep in mind that many opto's often offer 10kV or more isolation. They expect you are considering the air gap and the component is fully potted.

Most OEM ignition chips that I've seen have been protected, for between 350V to 450V. Perhaps larger coils instead of CDI pencils have a higher kick back.

I'm going to punish you metric folks by talking in metric-ounce and the metric-foot :twisted:
https://en.wikipedia.org/wiki/List_of_unusual_units_of_measurement#Metric_foot

Some day I need to make metric more intuitive to me. I just don't have that gut feel. I guess at the same time I can learn how to speak English ;) While English is my first language, my primary form of communication is mis, that's miscommunication.
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Re: Prometheus - NEW compact ECU shield!

Post by mobyfab »

Haha one day us metric folks will conquer the world! (There's only USA left anyway :D )

I was talking about the inside of the ECU since you have to drive the primary directly there, all pencil coils are potted anyway indeed.
I remember seeing the CBR coils spiking going up around 120v on the primary and 20Kv on the secondary, but they'd probably go higher if you remove the plugs.
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Re: Prometheus - NEW compact ECU shield!

Post by Dron_Gus »

AFAIR BIP373 have active voltage clamp. So voltage should not rise above ~25V.
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Re: Prometheus - NEW compact ECU shield!

Post by kb1gtt »

I see a clamp between 350V to 450V.
Capture.PNG
Capture.PNG (81.03 KiB) Viewed 43897 times
You need this kind of voltage for the primary as the coils are typically about a 100:1 multiplier. AkA approx 300V = 30,000V spark voltage. Also approx, 35mils = 35,000V. Sorry for the mils instead of metric, but it does work out for this approximation.

In reality your spark voltage depends on things like compression ratio, humidity, temperature, ect. As well I think that coils are more commonly 110:1 not 100:1, ect. But for easy math's and approximations....
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Re: Prometheus - NEW compact ECU shield!

Post by Dron_Gus »

kb1gtt wrote:I see a clamp between 350V to 450V.
Capture.PNG
You need this kind of voltage for the primary as the coils are typically about a 100:1 multiplier. AkA approx 300V = 30,000V spark voltage. Also approx, 35mils = 35,000V. Sorry for the mils instead of metric, but it does work out for this approximation.

In reality your spark voltage depends on things like compression ratio, humidity, temperature, ect. As well I think that coils are more commonly 110:1 not 100:1, ect. But for easy math's and approximations....
Ups. My mistake. Was looking at wrong parameter.
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Re: Prometheus - NEW compact ECU shield!

Post by andreika »

kb1gtt wrote:I see a clamp between 350V to 450V.
FYI, here's also the excerpt from GOST-23.751-86 standard for break-down voltage of pcb traces:
GOST-23.751-86.png
GOST-23.751-86.png (17.26 KiB) Viewed 43770 times
According to this standard, we're good - as long as relative humidity is not too high.
But if the ECU is under the hood, a protective insulating coating is a must (especially as gasoline vapor may affect pcb).
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Re: Prometheus - NEW compact ECU shield!

Post by kb1gtt »

Break down voltage and creepage / clearance distances are 2 different things. The breakdown is when the you get an ionized path which changes the impedance from high ohms to low ohms. Creepage / clearance distances are when your have energy leaking from high voltage to low voltage sources. Think of it like your how your hair tends to stand up on your head before a lighting storm.

It looks like that GOST is a Russian standard. I am not familiar with it or the context of this table. I would need more information about what the test conditions that were used to make that table, before I can use it for making decisions.
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