OBD MPGuino gauge - Page 11 - Fuel Economy, Hypermiling, EcoModding News and Forum

tom43571 · 07-11-2008, 05:48 PM

I wonder why I cant get mine to display anything but OBD-II ISO9141-2. My serial monitor just shows "initialization"

n8thegr8 · 07-11-2008, 11:21 PM

bleh, plugged it up in the car tonight and turns out I suck, lol. Best as I can tell, I'm going to have to get some transistors to drive the lines, but I still don't know how I'm going to get it to read back the data, because the pulsein() Idea I had isn't working worth crap.I'm going to look into getting samples of some driver chips so I can cheat, lol. I dunno, I think I'm way out of my league on this one, but I'm gonna keep trying. I REALLY wish I had an O-scope to see if the car's responding....

cmags · 07-12-2008, 08:49 AM

Well, I think it was posted here before, but here it is again with a direct link to the trunk: Revision 4: /trunk

You might be able to look over their code for some of the basics... GL!

Magister · 07-14-2008, 02:27 PM

I tested in my car but after sending the 0x33 at 5 bauds it seems I get no answer from the ECU. I should bring a scope in the car :-/

Magister · 07-15-2008, 01:43 PM

My interface is finally completed, I rewired it with 28AWG instead of 22 (what I had around), it's nicer

On my bench I tested the output of the ISO line of the MC33290 with a scope when I send the 0x33 and it's ok. I am wondering if the 2 grounds in the car are connected or not (pin 1 and 2 of the OBD2 connector). I will do a test with the MC ground on pin 1.
Else I will take an inverter and a scope in the car to test signals.

n8thegr8 · 07-15-2008, 10:21 PM

nice, I wish I had a scope, then I could compare the signals from my usb adapter with those from my arduino. I've all but stopped messing with it atm, because I really am stuck and school's creepin up. bleh.

tom43571 · 07-16-2008, 11:57 PM

Wow, nice work on the diagrams magister

Magister · 07-17-2008, 09:17 AM

Quote:

Originally Posted by tom43571

Wow, nice work on the diagrams magister

Thanks

I made some wiki page on the project too
opengauge - Google Code

Magister · 07-17-2008, 01:16 PM

I tested with a scope in my car and when I send the 0x33, all the timings are correct on the K line, but the ECU does not answer, the bus is always high and I see no start bit (active low) coming

I am starting to wonder if my car answer to the slow init or if I need the fast init or the iso init sequence

whitevette · 07-20-2008, 01:09 AM

Under "MAF Sensor" in the list of constants...someone needs to change "4.54" grams per pound to "454" !! This decimal point is lost!
I didn't check the others, but they look OK at a glance. -whitevette