OBD MPGuino gauge

[tom43571]

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

[n8thegr8]

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]

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]

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]

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]

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]

Wow, nice work on the diagrams magister

[Magister]

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]

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]

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

[tom43571]

Anybody having any luck?

[n8thegr8]

sorry I've been out of the loop for a while, I ordered parts today to build a logic analyzer so that I can compare what my (working) usb obd reader does compared to my arduino and adjust accordingly (only like $10 in parts). I'm also thinking I'm going to have to ditch the pulseIn method and setup the analog comparator manually

off topic, the logic analyzer should also come in handy in getting my arduino to control my zune, which is the only thing I'm lacking with my integration setup compared to when I was using an ipod, woot!

[cmags]

$10 in parts for a logic analyzer?? Do you have a schematic/part list for this? (Damn, and I *just* received an order from Mouser...)

[n8thegr8]

here's the site: http://www.geocities.com/ted_rossin/...#LogicAnalyzer

Schematic: http://www.geocities.com/ted_rossin/...heapLogicA.jpg

parts list from mouser invoice (sans the max243, which I ordered as a sample from maxim):

ORDERED STOCK NUMBER SHIPPED PRICE EXTENDED
-----------------------------------------------------------------
1 152-3309 1 1.190 1.19
Kobiconn D-Sub Conne
9C R/A PCB PLUG

1 71-CCF07-G-1K 1 0.020 0.02
Vishay/Dale 1/4WATT
1/4watt 1Kohms 2%

1 71-CCF07-J-47K 1 0.020 0.02
Vishay/Dale 1/4WATT
1/4watt 47Kohms 5%

2 140-50N5-220J-TB-RC 2 0.060 0.12
Xicon Class 1 Cerami
50V 22pF NPO

1 520-HCA2000-20X 1 0.400 0.40
ECS HC-49/U Micropro
20MHz 20pF

4 80-C322C104M5U5HA 4 0.120 0.48
Kemet Conformally Co
50volts 0.1uF 20%

1 579-PIC16F87304SP 1 7.460 7.46
Microchip PICmicro -
7KB 192 RAM 22 I/O

ended up about 16$ after shipping. It's an rs232 based logic analyzer that displays and logs data on your pc. You'll also need a pic programmer if you don't have one already. Dunno how well it works but I figure it's worth a shot. you can do one cheaper with a parallel port, but my lappy's only got serial.

[Magister]

guys, I am busy these weeks but will re-start to work on it next week!

[Magister]

I re-did some test and I don't know where to continue now

I checked that my car use only K line and not L, which is ok, I also have the CAN pins but as it's a 07 it should work with the "old" iso protocol.

I added init for ISO14230 fast and slow but it changes nothing.

I monitored the output of my circuit and I rightly output on the OBD2 plug, timing for the 5 bauds init is right to the millisecond according to my scope.

However my ECU never answer something, the K line is always high and the ECU never pull it down to start to send someting (a start bit), I monitored with the scope in the car!

I re-checked our hardware design and it seems ok AFAIK.

I will try to find some help on the avrfreaks forum maybe?

[Magister]

Ok' I tried ISO9141 and ISO14230 and tried with an address from 0x01 to 0x7F without success.

It seems my car (Elantra 2007) is CAN only


CAN is also used for the electric power steering, etc.

And there is no VSS on my car anyway so I can not use the MPGuino!
There is only a WSS, a right front wheel speed sensor.

I may let the ISO OBDuino in the hand of someone else and start again with a AT90CAN or an ELM327

[dcb]

no vss? That is hard to imagine, wss sounds suitable, might need a transistor to make it useable by the guino or something.

If you can decypher the can protocol on the atmega168 then that would simplify things quite a bit. CAN IS the standard for new cars for the short term anyway. the 327 would be a nice generic chip too, but someone mentioned it was slow?

[Magister]

Yes it seems the Elantra does not have VSS!!

The 327 by default works at 9600 bauds but can be set to 38400 bauds which is better.

I am taking a look at CAN spec but OMG it looks like more complicated :-/

I may take an ELM327 and interface it directly to the arduino (tx and rx) for the AT commands, and with a MCP2551 (The MCP2551 is a high-speed CAN transceiver, fault-tolerant device that serves as the interface between a CAN protocol controller and the physical bus) for CAN.

[dcb]

WSS should be fine, my vss on the saturn is technically a left wheel speed sensor (it senses the speed on the left axle).