Page 1 of 2

Description of the OpenECU hardware interface I'm working on

PostPosted: Tue Jan 04, 2005 9:24 am
by cboles
Since the hardware hasn't hit production yet, I thought I'd spend a few minutes describing exactly what the hardware is that I'm working on and soliciting any feedback you might have. Here's a feature list:

* USB interface using FTDI USB<->Serial interface chip which supports emulation of a COM port with drivers for Windows CE/98/ME/2000/XP, Mac OS 8/9/X, and Linux. This allows our software to communicate using standard COM port i/o calls, but support a USB connection.

* all the electronics fit inside the J1962 OBDII connector shell, and a captive 2m USB 'A' cable connects to your computer.

* the same circuit board can be populated differently and have a captive DE-9 serial port cable instead (non-USB option).

* optically isolated ISO 9141 interface with extra lines for special Subaru pins on the OBDII J1962 connector

* the unit can be modified to be permanently wired into the car for less obstruction when datalogging.

* ability to operate at obscure baud rates accurately

* software compatible with some other hardware interfaces, e.g. EcuTek DeltaDash - preventing you from having to switch hardware when running different tools.

* reliable, robotically assembled, surface-mount design.

* units will cost less than $100 in single quantities initially (could become cheaper once I can recoup production costs).

Sound good, but if you want sugestions...

PostPosted: Tue Jan 04, 2005 12:30 pm
by bofh
Many people will already have some type of ODB2 reader. This means many will have an ODB2 cable. Would it cut cost if we could get a board with a DB9 on the end that will go to an existing cable? The other end would have a DB9 or a USB depending on application, or could we populate the board to handle both? (DB9 for the very old laptop, and USB for the palm, or vise versa for old palms and new laptops)

PostPosted: Tue Jan 04, 2005 2:00 pm
by cboles
It's definitely a tradeoff between supporting the bits and pieces some of us already have and making a new unit for the minimum price. Here are some thoughts.

* the case design I'm using has a J1962 connector integrated into it. This case is almost as cheap as any other I could use, which means that the J1962 connector basically comes for free, instead of paying ~$5 for a J1962 connector+pins+crimping+striping+soldering or $15-$20 for a DE9 to J1962 cable. What I'm saying is, the lowest price solution I have found so far for somone who has no goodies lying around is this.

* all of the ODBII cable assemblies I looked at that use a DE9 on the other end choose a set of pins which is incompatible with Subaru reflashing as a 12V Vpp voltage needs to be provided on J1962 Pin 11, which isn't wired through on these cables. The HD-15 type cables do have it, but this isn't what people have lying around.

To answer your other question (if I understand it right) - yes - the board can be populated to support a DE9 which can connect directly to an old laptop. The limitation here would be that if the ECU requires an odd baud rate, you will be out of luck. From what I have seen, the 2002-2003 WRX can be reflashed just using 9600 baud though. The 2004-2005 WRX needs 15625 for part of the process. Don't know about the STi/FXT yet. If anyone in the Seattle area has an STi/FXT AccessPort or a Subaru Select Monitor - I'd love to meet up with you!

PostPosted: Tue Jan 04, 2005 2:12 pm
by Synx
We have a some different cable options as well for those who would rather build that buy this device.

http://www.multiplex-engineering.com/
From what i understand they sell cables with the OBDII plug on them...

And i have a box of connectors at home and i cannot remember right now where i got them. But it was a company that makes them for car manufs. and i just called and requested samples of the male plugs. Although it did take some social engineering to get them to send to me it was fairly easy and free!!!

But really for those doing the full time data logging and what not id just splice into the wires on the back.

-edit-
Also would you mind posting the chip info on the usb interface im intrested in seeing this.

On my embedded board ive got just a USART and i use timers built into the board to clock it to what ever i want so i can for the most part get any baud rate stable, but like you said on a PC its a different story and getting 5baud for OBDII (which were not using but just an example) is like pulling teeth from most laptops lol.

-edit again-
Sorry didn't see the link to that site for the USB to UART. I dont see it being too hard to setup a PIC with USB and serial to do that job either. But for the small package your building looks like you've got some awesome chips ;)

PostPosted: Tue Jan 04, 2005 3:18 pm
by cboles
Yew - Multiplex Engineering is the cheapest source I know of for low qty. J1962 connectors. They do have a $50 minimum though. The way I am going for the connector is also cheap for the DIYer

PostPosted: Wed Jan 12, 2005 11:30 am
by cboles
It looks like I'm going to have to omit the RS-232 option on the interface board and only support populating the board with a USB interface. The board inside the connector is just to small to support the 7 additional parts plus terminals for wiring up a RS-232 cable. If there's enough interest, I can make another RS-232 board sometime later.

PostPosted: Wed Jan 12, 2005 1:39 pm
by happasaiyan
if we could get it to work with a full usb interface, that would be the bomb-diggity. much faster and more responsive than serial.

PostPosted: Wed Jan 12, 2005 1:46 pm
by cboles
I like USB too. Just so you know, this is still a USB<->Serial interface chip living inside, so to the operating system, it still looks like a RS-232 port. This way we can develop software for the serial port that works both over USB and by good old RS-232. The speed is set by the ISO K-line interface, so there is no speed difference between the two methods. The USB chip allows for funky baud rates though.

PostPosted: Wed Jan 12, 2005 3:46 pm
by mumbles
USB is the way to go.... even older laptops have USB, and if your old laptop doesn't have USB, then you are due for a newer old laptop!

PostPosted: Thu Jan 13, 2005 2:18 am
by DaveImpreza
sorry cboles, where we can buy one of these nice connectors u use ? And what is the "low" cost of these ?

Thanks
David

Here's a shot of the board layout completed

PostPosted: Thu Jan 13, 2005 3:46 pm
by cboles
Here's a shot of the board layout completed. This is actually two boards that join perpendicularly inside to connector shell to make the complete USB<->OBD2+Subaru interface.

Image

PostPosted: Thu Jan 13, 2005 3:51 pm
by cboles
DaveImpreza: click on the hyperlinked text in my earlier post to visit the site which makes the connectors.

PostPosted: Fri Jan 21, 2005 1:00 pm
by mumbles
That looks sweet, when is it going into production?

PostPosted: Wed Jan 26, 2005 10:48 am
by cboles
The circuit board and cables are being made as we speak. The cables are coming from China, and I should have those in 3-4 weeks, which is hopefully the time it will take to get the boards assembled too. I should have the hardware done and ready for people to use in about 6 weeks. I wish it could be quicker, but that still pretty quick for a finished hardware product which is nicer than most of the OBD2 type interfaces you see out there (IMHO).

Need help?

PostPosted: Thu Jan 27, 2005 7:40 pm
by bofh
I am handy with a soldering iron... I may have the cables needed, so I could test before China gets here. Oh, and I am impatient. :twisted: Seriously, I think the boards have been dead, waiting on something to actually work with. With this, we can start pulling stuff off the ECU. With this we can start "Browsing the mibs" to use an SNMP phrase. Ready to get moving!