OBD MPGuino gauge - Page 41 - Fuel Economy, Hypermiling, EcoModding News and Forum

Froggy · 05-28-2009, 10:09 PM

More success. I was getting some strange data on the screen (relating to reading ECU data when the car is off), but that is solved . Now saved data seems very stable. (Example: I was at $.97 for trip cost before I shut it off and it was something like $1.13 when I started the car up again. - Yikes!)

I noticed that the outing distance was not getting reset, that was a simple fix too.

I also added a button mode to identify what the PIDs are on the screen. Being new to this device, I sometimes find myself wondering "What is THAT number about?" so now I just press both the left and right buttons, and the PID info comes up for a second, then goes away.

After I try the dedicated L line interface, it will be time to put this in a case of some sort. Right now it's mounted on cardboard with all the wires showing... not exactly nice looking.

Oh, I didn't use the DB9 connection, but the smaller J45 connection. For a cable, I just ordered the ScanGaugeII extra cable.

electromike · 05-30-2009, 09:23 AM

Great work. I like the idea's of the Left and Right button push to bring up the descriptions. When you find that all your changes are stable, we should get them merged into the project.

Froggy · 05-30-2009, 11:51 AM

I have found the Left and Right button handy...

I found the instant cons to have a -1 before the car starts... Haven't found the cause yet as I have not started working on it. Everything else seems good. I also have regression testing to do.

How shall we get the changes merged in?

mattjreilly · 06-04-2009, 10:21 AM

Well, I got mine together and i gets as far as the ISO 9141 init screen which then fails. My car is a 1995 Subaru Legacy Outback (yes it's OBD-II, an early one) and since it is so early I'm wondering if it needs the L-line as well, I remember reading earlier in the thread that it may have been used early on. I'm going to try jumpering the L to the K. Froggy, need someone else to test your code?

I built my Obduino with an iDuino (and the Freescale chip for ISO) so I was wondering how I would power it since it has no 9v pins. What I ended up doing is taking apart a car-USB adapter and connecting it to the 12v at the OBD-II plug and the 5v at the iDuino. It seems to work but I it seems to be a very dirty signal, I see it in the LCD. Any suggestions on cleaning up the adapter or should I just build a power supply for it.

Great work guys,

Matt

Mart · 06-04-2009, 10:31 AM

I had no success using the freescale mc33290 with my 06 subaru STI using obduino32k. I implemented the OBD-Microcontroller Interface (prj.perquin.com) and used the proprietary Subaru Select Monitor (SSM) and I have a working device displaying (MPG, RPM, BATT, BOOST etc..) since last night. Next step is logging

dcb · 06-04-2009, 10:36 AM

Hmm... well that is good news for you

I couldn't really tell what the mc33290 did to the signals (like if it was inverting them or what). I love the simplicity of that perquin circuit though, glad someone got it working

Mart · 06-04-2009, 10:38 AM

well according to some pseudo support from freeacale it should NOT invert the signal... this is not what I have seen on the scope.. hence why I switched to the perquin circuit and validated that the signal was correct

.. from there it was an easy ride... once you got the hardware straight.. it is trivial to me...

I will revisit the mc33290 soon but right now I have many features I want to add to my device...

and now I need a control button BMW style that doesnt cost an arm and a leg and is easy to interface with...

Mart

Quote:

Originally Posted by dcb

Hmm... well that is good news for you

I couldn't really tell what the mc33290 did to the signals (like if it was inverting them or what). I love the simplicity of that perquin circuit though, glad someone got it working

mattjreilly · 06-04-2009, 10:54 AM

Looking at the Obduino schematic I just want to verify something. The diagram indicates that pin 5 of the MC33290 is the TX pin and it goes to the TX pin on the *duino and pin 6 of the MC33290 is the RX pin and it goes to the RX pin on the *duino. Is this correct? Sorry if it's a stupid question, it just seems like the TX pin on one should go to the RX pin on the other.

Matt

mattjreilly · 06-04-2009, 11:01 AM

I found this link to a OBD-II compatibility chart if anyone is interested.

OBD-II Compatibility

Froggy · 06-04-2009, 11:25 AM

The MC33290 is a communication chip, and it's RX and TX pins are seen from the device side not the cars. (Thus a TX = device is sending to car. RX = device to recieve this from car.)

When I switched Rx and Tx arduino pins, communication stopped.