Data Link Connector bus switching?

Ideas and discussion of what to do with the CAN Bus ( i.e. XMDirect, iPod, Carputer, etc... )
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nr0x
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Data Link Connector bus switching?

Post by nr0x » 2014 Jun 21 19:52

So here is my brilliant "evil" plan for my 2014 Jeep Wrangler.

1. Tap into the interior bus in the dash.
2. Use a DP/DT switch to toggle between the interior and diagnostic bus on the data link port.
3. Try to screw up the interior bus with an ELM327
4. Accidentally cause the Jeep to become self aware, where it will drive off into the wilderness and spawn a new race of super Jeeps, which I will use to take over the world.

Nr0x

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linuxkidd
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Re: Data Link Connector bus switching?

Post by linuxkidd » 2014 Jun 28 23:35

Nice plan! Just make sure your switch is break before make.. :)

LK
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nr0x
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Re: Data Link Connector bus switching?

Post by nr0x » 2014 Jun 29 15:29

Good idea! I hadn't thought of that! Fortunately, it turns out that the switch I got is just that.
The wiring change went fine, and I can now switch between diag, and interior busses. The elm327 seems to play nicely using AT SP B for protocol. I did the cute little EVIC trick. It's a great way to test the lights when I hook the camper up! I can stand in back and send the various light commands and see that the trailer lights are good.

My next project will be to try and interface a PICAXE chip to the elm327 through a little $5 bluetooth module I ordered off ebay. The goal is to get the PICAXE to respond to specific bus messages. If I can get that going, then the REAL fun begins.

nr0x
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Re: Data Link Connector bus switching?

Post by nr0x » 2014 Jul 04 17:10

So of course I had to take my toys apart. I decided to Crack the case on my cute little elm327 module, and I was pretty surprised at what I found. The can interface module, with a separate bluetooth module just tack soldered onto the main board. The BT module looks like a HC-05 clone. Which means it's probably just a TTL level serial interface between the 2. Looking at datasheets, I confirmed that.

That's when I got my brilliant idea...

If I take the bluetooth module OFF the board, I can put a picaxe in its place, and have an easy way to talk to the canbus. Then I can also use the bluetooth module for other picaxe chaos and mayhem.

Now, if I only had a smaller soldering iron, and hadn't destroyed both boards while trying to get them apart!

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linuxkidd
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Re: Data Link Connector bus switching?

Post by linuxkidd » 2014 Jul 04 21:05

Ouch... Been there before.. good luck with your next one!
If you can read this, the light is still red.

nr0x
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Re: Data Link Connector bus switching?

Post by nr0x » 2014 Jul 18 17:42

Well, I'm still waiting for parts from eBay (Chinatown), but I got to taking a look at the remains of the elm327 that I fried. I melted the copper off the board when I was trying to remove the bluetooth module. But...

I followed the traces, and managed to find a spot whereI could scrape the paint off, revealing fresh copper. I took the soldering iron out and VERY CAREFULLY soldered 3 wires to the board, and secured them by putting a zip strip through a hole to keep the strain off the solder joints. I used an old CD-Rom connector. The little 4 pin cable they used to use to connect the drive to the soundcard? Yea, that guy. I plugged it into a project board, fed 12 volts to it, and wired it up to a CP2012 usb/uart adapter I had lying around. I brought up the terminal software, set it for 38400 and....

ELM327 c1.5

>

SWEET!!!! back in business again, and with another bonus, i used a usb-otg cable, plugged the adapter into my Galaxy s5, got on the Play Store, and found a usb serial terminal program, and brought the interface up from my phone. Now I will bet there is some way to virtual-cable that thing to the phone's bluetooth.
Here's the app for the phone.
https://play.google.com/store/apps/deta ... eeusbtools

Now this also means I can put a PICAXE on the proto-board, and since the levels are already 5 volts, I can talk directly to the interior bus with a picaxe.

(insert chaos and mayhem here)

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linuxkidd
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Re: Data Link Connector bus switching?

Post by linuxkidd » 2014 Jul 18 18:35

Nice job nr0x! Eager to see the chaos and mahem.. ;)
If you can read this, the light is still red.

nr0x
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Re: Data Link Connector bus switching?

Post by nr0x » 2014 Aug 11 20:37

No dice. Turns out that, while the 327 answers modem commands, it won't transfer data from the bus. No big deal. Threw it on the trash. My new ones came in from FleaBay though. And in true dumbass form, I opened it up to do thesame thing that broke the last one. But this time I didn't break anything. I also managed to get the bluetooth module into command mode so I could rename and change the pin. After that, I soldered the module back on, and tested that everything still works. I'm holding on the picaxe interface until my hc-05 bluetooth modules come in.

So yea...I haven't really done anything.

nr0x
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Re: Data Link Connector bus switching?

Post by nr0x » 2014 Sep 02 16:21

So I ordered some HC-05 bluetooth modules from ebay, and after 2 months, they never showed up. the seller HKPowerstore fed me a line and said they were on their way, but wouldn't give me any tracking info. I got a refund and ordered from somewhere else, and they just showed up in the mail today. So now I'm going to tinker with them a bit, and get one wired up to a picaxe so I can talk to the elm327 in the Jeep. For now, I will start with basic setup commands, and a couple of canned messages for the evic.

nr0x
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Re: Data Link Connector bus switching?

Post by nr0x » 2015 Jan 27 13:00

Last night I managed to the a PICAXE chip to send commands to the ELM327 clone over bluetooth. THe picaxe can connect to the module, and can send it all the usual startup configuration commands. I also worked out a trick to convert ASCII test into hex characters that can be used for 295 messages, or whatever. I'm going to try and work on a scrolling display for the dash today. 8 characters just isn't enough room! IF anyone is interested, I'll post picaxe code.

NR0X

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