OpenPort schematic

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OpenPort schematic

Postby cboles » Tue Jun 28, 2005 3:33 pm

A few people have asked me for the schematic of the OpenPort USB to ISO-9141 interface so that they can better understand how a ISO-9141 physical interface works. This particular work is copyright Tactrix Inc., so it is for personal use or educational reference only. Enjoy!

[edit] I have now updated this post to also show the OpenPort 1.2 schematic.
Attachments
openecuport12.pdf
OpenPort 1.2 Schematic
(348.21 KiB) Downloaded 7118 times
openport.pdf
OpenPort 1.0 Schematic
(24.37 KiB) Downloaded 3997 times
Last edited by cboles on Tue Nov 29, 2005 8:16 am, edited 1 time in total.
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Postby DaveImpreza » Mon Jul 11, 2005 10:21 pm

Hi,

you think it's possible to connect optocouplers directly on RS232 connector, if anyone don't want to use usb to rs232 converter chip ?
Or it must be exchanged with another like max232 ?
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Postby calvinc » Tue Jul 26, 2005 9:46 pm

colby,

what is pin15 for? it is shown on the schematic as shorted to pin9 but the tactrix connectors dont have a pin15.

calvin.
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Postby cboles » Wed Jul 27, 2005 7:15 am

DaveImpreza wrote:Hi,

you think it's possible to connect optocouplers directly on RS232 connector, if anyone don't want to use usb to rs232 converter chip ?
Or it must be exchanged with another like max232 ?


If you search the internet, many other designs do exactly what you are describing. One of they key reasons I choose to use the converter chip is its ability to generate unusual baud rates which are needed for some operations on some ECUs. In general, PC UARTs are not able to do these rates. Also, PC UARTs have inconsistent RS-232 drive levels.
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Postby cboles » Wed Jul 27, 2005 7:18 am

calvinc wrote:colby,

what is pin15 for? it is shown on the schematic as shorted to pin9 but the tactrix connectors dont have a pin15.

calvin.


It is the "L" line used on some ISO cars. I chose not to populate it on this version, but it could be used in this way. The schematic represents all possible circuits (but not necessarily all populated components) on the PCB.
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Postby moxie » Mon Dec 12, 2005 2:34 pm

How much money can honestly be saved by making your own cable?

I merely ask because I want to decide if it is worth the effort.

Lets just say it would have to be cheap since I would have a lot of work to do , and I wouldn't be supporting the community
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Postby Spiider » Mon Dec 12, 2005 3:51 pm

Go to digikey and add it up...you won't save much. Plus, the OBD2 male is hard to find in single quanitities.

The cost will go up quickly if you don't have a certain amount of electronics expertise and screw up the first one.

I really don't think you can do it cheaper yourself.
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Postby moxie » Mon Dec 12, 2005 4:52 pm

I didn't think so :)

Holiday season and all... Just investigating my options ;)


Thanks!

I'll just buy the OpenPort in a week or so
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Postby onesixnin » Wed Jan 25, 2006 8:39 am

where's the schematic?
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Postby cdvma » Sat Jan 28, 2006 7:43 pm

Its there in the first post, the PDF attachments.
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Postby combatcqb » Sun Mar 19, 2006 8:19 pm

Hi Colby, do you mind sharing the reason for switching from optocouplers to voltage comparators? Was it just cost?
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Postby cboles » Mon Mar 20, 2006 12:19 am

It's a little cheaper, but the main reasons are:

speed: optocouplers burn a lot of current to get high bandwidth. the OpenPort 1.2 will loopback test at 1Mb/s, the OpenPort 1.0 is typically around 60kb/s.

reliability: optocoupler have poor tolerances and age

space: optocouplers take up lots of board area

precision: switching thresholds are hard to control with the optocoupler (unless you add comparators on the auto side)
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Postby WOTboy » Mon Apr 03, 2006 7:33 pm

onesixnin wrote:where's the schematic?


You have to be logged in. :P
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PDF download issue

Postby DJesco » Wed Feb 06, 2008 12:13 pm

I hate to sound like a noob but I am logged in. However I seem to just get an icon instead of the pdf. I have acrobat reader installed. :(
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Postby Jon [in CT] » Wed Feb 06, 2008 1:25 pm

What happens when you try to download the 1.3U schematic at http://forums.openecu.org/viewtopic.php?p=6829#6829?
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