OBD MPGuino gauge - Page 63 - Fuel Economy, Hypermiling, EcoModding News and Forum

Bix · 03-13-2011, 01:12 AM

Has anyone been able to find the MC33290? Or perhaps if someone has a few lying around they could send one to me? (ill pay

)

Also if the board has nothing connected to tx and rx, should it display properly? Testing it out it seems a bit strange, shows obduino security and erratic menus.

DJ_SpaRky · 03-13-2011, 01:37 PM

@Bix:

You can built one of the transistor arrays instead, go to prj.perquin.com/obdii/ for more info on that. (sorry, can't post links or pics, post count is too low)

Also, if there is nothing connected to input, the LCD should show the "Car Alarm" screen, or "Init Failed" error. You might want to check the line that says "// 40 does not work with some LCD, or some misterious problem so try 0 if it does not work" Should be Line 787 or so. I had to change it to 0 to keep Kanji Characters from displaying instead of the * for the "Car Alarm" screen.

Bix · 03-13-2011, 08:19 PM

Where can I find the -12v in the car?

DJ_SpaRky · 03-13-2011, 08:44 PM

12v is OBD-II Pin 16, should be the lower right corner pin on the connector in the car.

Bix · 03-13-2011, 09:09 PM

The diagram shows +12v, -12v and ground, I.e a difference of 24v across the collector and emitter of the transistors. How do I get around this?

DJ_SpaRky · 03-14-2011, 12:33 AM

You are looking at the OBDII-to-RS232, but you need the other Picture, the OBDII-to-AVR(ATmega) picture. I'd post it, but my post count is still too low.

Bix · 03-15-2011, 05:24 AM

Hey guys, do you think this chip is a suitible replacment to the mc33290?

Vishay Si9241:
ISO Transceiver 9141 Vishay Si9241 OBD 1/2 Diagnose NEU - eBay (item 320667593426 end time Apr-05-11 14:03:30 PDT)

I've tried the method you presented sparky, sadly it doesn't seem to be working - i'll have a few more shots at it but if it doesn't work i'll get the chip.

DJ_SpaRky · 03-15-2011, 11:52 AM

Looks like it will work: datasheetcatalog.org/datasheet/vishay/70013.pdf

Funny enough I tried it to and it didn't work, I'm having a friend that is better skilled at soldering rebuild it and if that doesn't work, I'll try to find a Chip

Bix · 03-18-2011, 06:04 AM

The Si9241 looks to be an ideal replacement and it can be found on numerous places for order. However it is slightly different, it has a logic pin CS that toggles it's mode from transmit to receive. So when this pin is low, its in tx mode and when it is in high it is in rx mode.

I don't know how the code works (2000 lines...) and I don't know how the ecu communicates, so could someone please explain how the arduino communicates to the ecu? Could it be as simple as connecting the RX pin to the CS pin so that when RX is high, CS is also high?

njakts · 03-18-2011, 08:29 AM

HI fellas!
where to find latest code for obduino?

I found this
http://opengauge.googlecode.com/svn-...obduino32K.pde
but ir runs like in a demo mode.
is there a way to disable the demo?