Puma board for FreeEMS

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

Post by Fred »

Jammi wrote:How about 4N35 series optocouplers? They seem to be generic, availability is good and are not very expensive.
They are available in SMD (singles) and cost between 10 and 50 US cents, not too bad IMO. Good call Jammi.
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Re: Puma board for FreeEMS

Post by Fred »

viewtopic.php?f=9&t=1233

Some of this is non-essential or too far off for this design, but other parts are not.

Fred.
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nitrousnrg
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Re: Puma board for FreeEMS

Post by nitrousnrg »

Jammi wrote:
nitrousnrg wrote:Well, opto is expensive, big in size (at least the ones I saw) and there aren't many multi-channel ICs out there. There is a 6 channel RF isolator, though, that could be interesting. It was in the dirst drafts of the puma design and got removed.
How about 4N35 series optocouplers? They seem to be generic, availability is good and are not very expensive.
I may have a very distorted sense of size, but to me a dip6/so6 per channel is big. On te plus side, yes, they are cheap and available. I can even buy them here, and that is a *big* thing.

I'll leave the ft232 area not laid out for some days, I don't know if the usb isolation is a must.

The usb signal should'n be distorted, since its a diferential input, the usb 5v are separated from the boards 5v, and the ground... well, that could be problematic. Also, I've some expectations abut the SM modification to avoid the pnp hack.

Jared, yes, I konw you're into the case stuff, so soon enough I'll ask you a couple of things. Have fun in the NEFR!

Exam tonight, delivery tomorrow, exam on friday.
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Re: Puma board for FreeEMS

Post by jurpo »

I've used TLP18* as generic optocouplers, well available in SMD packages. E.g. TLP184 is quad open-collector optocoupler. Not very tiny but significantly smaller than 4x DIL6 or its SMD "gullwing" counterpart. Quite cheap and performance similar to 4N25 or 4N35 types, and if I remember correct they do not provide external "base" connection, or at least not in 4-lead packages.

Another IC-family which is quite useful, altough not so inexpensive, is ADUM (http://www.analog.com) digital isolators: bandwidth upto several Mbps or more, available in different configurations (e.g. 2x RX + 2x TX), capable of logic translation (3V logic to 5V logic and vice versa) and isolation is certified to over 1kV. Few con's are that those are 'active' devices so they need power supply to both sides of isolation barrier, and that they are not very cheap at least if compared to TLP or 4N* series.

Although ADUM's are integrated magnetic isolators they do have totem-pole outputs

- - -

I just happened to find this site and as a short background regarding to myself, I have been interested EFI management for a very long time and I also have build/collaborated several megasquirt projects past few years. It (MS, MSnS, MS-extra) still has some limitations and I am not pleased of its hardware, so I have designed few own PCB versions for that platform, although few latest designs from Bowling/Grippo have been more close to "decent" than previous ones.

I have been working about 10 years as a HW designer in R&D industry, and last 5 years in a consulting/engineering company. Mostly I've been involving embedded electronics and control designs incorporating different kind interfaces to sensors and actuators, and I definitely like to keep myself more analog than digital designer. ;)

Currently I am perhaps little bit too busy to participate fully for this kind of hobbies as I have a (building) construction yard awaiting for next few months. Unfortunately I don't have lots of free time to spend reading threads (until winter :D) but I am definitely interested to give you guys help e.g. in terms of reviewing designs, helping out component issues etc...

Seems that there aren't other-than-native design files available - please correct if I'm wrong - and for me it would be nice if a PDF version of the design would be available somewhere.
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Re: Puma board for FreeEMS

Post by Fred »

jurpo, welcome to the site! If you want to contribute to the most active design project going on on this site, contribute to RavAGE. Marcos is still working on Spin 2 of Puma, however the (publicly visible) pace is slow. I'm going to link your post in Dan's comments thread now, as it may be of use to him also. Thanks for posting! :-)
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Re: Puma board for FreeEMS

Post by jharvey »

jurpo, welcome along and glad to see your comments. Fred is correct in that Marco has been bumping up other priorities and PUMA dev has slowed lately. RavAGE is moving along however it uses Altium (sp) so most of us can't help directly.

How are you with git? I can help offer advice on how to check out spin1, which was made months ago, or I can offer advice about how to check out the most recent. It was done with KICAD, so you can access the raw design files, in the schematic capture / PCB layout software. I seem to recall a PDF copy does exist, somewhere, but I forget where. Perhaps the easiest way for you to comment is to install KICAD, then get the copy via download button found here. https://github.com/nitrousnrg/puma

If you would prefer the PDF copy, I can generate it and send it your way.

Welcome along and I look forward to your input.
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Dan
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Re: Puma board for FreeEMS

Post by Dan »

jurpo: so nice opto's there mate. Welcome to FreeEMS! I am working on RavAGE and although the design is in Altium Designer 10 format, I also generate a pdf copy for all to view. Feel free to check it out http://www.github.com/dvisser/ravage/
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Re: Puma board for FreeEMS

Post by jharvey »

I used the 4n25 years ago on a HAM radio project I did. That certainly was a well performing low cost opto. It worked well for my application. I seem to recall a key concern we had was packaging. It would be nice to have a large number of those in one small package. I'll go look at the AD stuff some time.
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Re: Puma board for FreeEMS

Post by jurpo »

Mostly I have used PADS at work, but I am well familiar also with Orcad, Altium and and Eagle, and to these I have licences to all but Eagle through my job. Kicad is totally new to me but so far it hasn't been problem to learn new CAD/CAE software - those are only tools.

I just returned from vacation so I have some time to spend to help you guys (and gals) as otherwise it would be too boring at work. If you wish to send me any schematics to be reviewed or checked here is my address: mikko dot juurela at gmail dot com (probably visible through my account as well).


Two long-time interests for me have been developing A) CDI ignition module and B) "smart" PWM injector controller.

CDI ignition is superior over standard flyback-type ignition and some commercial solutions are available but IMO the price tag is pretty high, too. I have already designed and simulated a low-cost, stand-alone single channel CDI module but so far I haven't had time to prototype it because other activities. It contains SMPS power supply capable to supply ~100mJ spark energy at 10kRPM and still it can nearly fit inside a matchbox. I think it would be easy to implement as a piggy-back PCB module to be used on different ECU designs.

The main reason for "smart" injector drivers is that I do not like the idea that (for low-Z injectors) you have to set time for opening pulse and then fixed PWM value for hold current as it has been in majority of aftermarket ECUs. Although usually it is performing fair enough, it still needs some investigation (or trial-and-error) until you can be sure that settings are good enough - until you decide to change different injectors. Infineon has few very interesting injector controllers but unfortunately they are not that easy to obtain (unless you are close relative to mr. Robert Bosch) as you need to order >1000 units before anything happens.

I saw that someone proposed to use LM1949 chip to provide 4:1 peak/hold current to injector. Otherwise it is quite good IC but the heat production will be real pain in the *ss because current control is done by means of linear current regulator. Let's assume that you have Bosch Motorsport injectors (1ohm) to control and you want to use 4A and 1A peak/hold currents, time to obtain peak current is 0.5ms and decay to 1A is another 0.5ms, and injection time is 5ms @ 6000RPM:
  • 6000RPM = 100Hz => t = 1/f = 10ms
  • duty cycle is 5ms/10ms = 50%
  • power loss during 4A peak (or 2A average, as starting from 0A): Ploss = 2A * [12V - (1ohm * 2A)] = 20W => Eloss = 20W * 0.0005sec = 10mJ
  • power loss during 1A hold current: Ploss = 1A * [12V - (1ohm * 1A)] = 11W => Eloss = 11W * 0.004sec = 44mJ
  • total loss energy: Etot = 10mJ + 44mJ = 54mJ => Ptot = 54mJ * 100 = 5,4W
  • Efficiency is roughly 10%, meaning that 10% of used energy is transferred to injector and rest is just heating the output transistor.
Power loss calculation is _very_ simplified, and correct method would be to use integral calculation method for 4A peak current transition but I am just too lazy. :oops: However, the energy loss during hold current is significantly larger and thus error in calculations is rather small.
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Re: Puma board for FreeEMS

Post by jharvey »

I've used PADS, Protel (Altium), Eagle, Orcad and of course GEDA. So far I'm happiest with KICAD for most things. My largest biffs are it's occasional lack of efficiency tools. Things like the ability to import a DXF or equiv to make an schematic symbol out of existing files, and other things like that.

One of Marco's (nitrousnrg) delays has been relative to the injector driver. It sounds like you might have some common interests there. PUMA spin1 used the LM chip, but he doesn't want to on the next spin. He's looking for something better, preferably SMT and PWM.

We have talked about the TLE6270 for direct injection purposes. I've been tempted to consider drafting an equiv, with OTS parts. But eh, I don't have a GDI at arms length right now.

Is your CDI module something you can/willing to share? I'd be interested in learning more.

About the smart injector driver, hows that work? Are you measuring uH as it opens, such that you can notice the pintle hit? Then use that as your known open time? I don't quite follow your smart injector drive concept.
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