MC33190

Developer topics relating to hardware that interfaces PCs to ECUs

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MC33190

Postby fabrik8 » Sun May 22, 2005 7:06 pm

Does anyone have schematics based on MC33199 instead of optos and transistors? This may be a very simple circuit, but I can't find any app schematics to verify anything. I'm making a micro interface, and don't need RS232 at all, so I'd rather try out the 33199, or it's 33290 replacement(without the L line). Is there any reason why the interface has to be optoisolated? If a microcontroller is using the same power supply as the ECU, why would isolation matter at all?

Will this setup (or any standard 232-ISO9141 interface) work for SSM use?

I'm very new to OBD2, please excuse my ignorance.
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Postby oman » Mon May 23, 2005 8:50 am

http://faq.ford77.ru/engine/ image/com_eec/adp_tk.png

Here's a mirror as that site seems to go down alot.
http://mongo.ducker.org/~oman/adp_tk.png

You can easily adapt that to the 33290 by just not worrying about the extra pins that don't appear on the chip. The 33290 is extremely straightforward to use. These interfaces work with more usb-serial converters than the optoisolated ones do because they don't expect the rs-232 side to actually power anything. They do tend to be slightly more expensive to build though.
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Postby sk_uk » Sun May 29, 2005 1:28 pm

Try http://www.skpang.co.uk/highspeed-iso9141.htm
Based on the MC33290D and MAX232
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Postby fabrik8 » Sun May 29, 2005 7:14 pm

Great, thanks for the help, that's exactly the type of example I was looking for.. But will it do SSM?

Does not using the L-line matter? I see it's not used, and I know the 33290 has no provision for it, so does communication still work without it?
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Postby richh » Tue Jan 31, 2006 12:33 am

fabrik8 wrote:Great, thanks for the help, that's exactly the type of example I was looking for.. But will it do SSM?

Does not using the L-line matter? I see it's not used, and I know the 33290 has no provision for it, so does communication still work without it?


Coming a bit late to this party, I know, but for what it's worth, the MC33290 works great with SSM. Lack of L-Line isn't an issue as Subaru don't use it, and neither do many other modern cars.

I've just built an interface using a 33290 and the FTDI-based DLP232 USB development module. It's difficult to imagine a simpler solution - including a status LED and reverse polarity/overvolt/overcurrent protection, there are just six components along with the DLP232 module and the interface IC itself. Certainly a lot simpler and neater than most other potential DIY solutions.

Sure, I can't flash with it ATM, but that's no issue as I'm using a JECS ECU anyway. As such the interface will do more than fine for logging in its current form, and will see me through until a flashing solution for the JECS is available. At this point I can either modify this interface, use the FTDI module as the basis of a new, flash capable one, or jump for one of Colby's. :)
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Postby fabrik8 » Tue Jan 31, 2006 7:40 am

Wow, that was exactly my plan.. Now if I just had time to do projects. Maybe this summer I'll start playing with this stuff again.

Thanks for the answer!
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Postby richh » Tue Jan 31, 2006 8:11 am

Heheheh, time? You don't need time for this one! :-D It's so easy it almost puts itself together!

Unless you're a perfectionist there's no reason to go out of your way to make a proper PCB, you can get away just fine with stripboard. Coping with the SMD chip is no biggie, I just fixed the 33290 to the board with an adhesive pad, then ran some traces down to the PCB tracks before encapsulating it in epoxy.

Even with the extra height of a socket for the 232 module, the resulting assembly is very small - sufficiently so to fit inside the larger "project" type DLC plugs I suspect. Given how easy it is, why wait? :)
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Postby fabrik8 » Tue Jan 31, 2006 10:22 am

Not time to make the board, time to use it do do stuff.
Making the tool is one thing, using it is another. =)
I'll probably make a batch of PCBs and deal them out to all my friends anyway..
I'm an electronics tech, but I'm back in school full time. I'm teaching myself C in my free time too.
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Postby richh » Tue Jan 31, 2006 11:21 am

Nuff said! ;)

Going back to your original post, my original plan with the MC33290 was to use one to interface a microcontroller with the K-line, so I'll let you know how that goes. On the face of it tho I don't see any reason why it shouldn't work fine - after all it's doing exactly the same job as it does with the DLP232.

Furthermore, as you suspect, any of the "dumb" ISO9141-2 IC's should work with SSM, as all the hardware is doing is a simple level conversion.
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