OBD MPGuino gauge

[Magister]

Originally Posted by dcb

You might want to bump up c1 to about 330uf or more to help prevent brownouts while cranking. Or draw it in context with the existing power supply.

I am not using this power supply schematic, I am using the +5 from the Arduino. This schematic is useful if you want to make a "true" ELM327 interface that will be plugged on a laptop for instance. The RS232 parts is not useful for us too as we plug directly the tx/rx on the rx/tx of the Arduino in a direct connect mode. As for power, the RS232 parts is useful only if you want to connect the ELM327 to a laptop.

Originally Posted by dcb

Lose the rs232 circuit all together and voltage monitor, there is probably a pid for system voltage, no?

There is no PID for voltage, so I take it from the ELM327, it's just a voltage divider that costs 15¢ to do and you retrieve the value with a ATRV command to the ELM, it's nice

About the possibility to connect the ELM327 to a laptop, I think I can do something. First I have to stop the application on the Arduino so it will stop sending thing on the serial port. Then I put an inverter switch on the tx/rx for them to become rx/tx so the ELM327 will use the MAX232 of the Arduino and I will just have to plug a cable between the laptop and the Arduino to talk directly to the ELM327. I will have to test first, it's just an idea, but it should work.

Originally Posted by dcb

I definitely like the color coding

You welcome

I am re-doing a proto with CAN/ISO, in a more standard way (point to point wire)

[zwoodward]

I'm new to all of this, arduino, schematics, everything. Is the OBDuino a project a newbie could tackle? I've been trying to follow this thread and am unsure if someone actually has a working version of the OBDuino in a CAN car? My father-in-law and I want to make a HUD with either the MPGuino or the OBDuino, we both drive 2008 cars that should be CAN (Ford Focus, Smart fortwo). We like the OBDuino because of all the info it seems to offer but the MPGuino looks way cheaper and easier for a newbie to make and program (it is available as a kit after all). A final question that our ability to make an HUD hinges on is whether or not the programming for these devices can be written in such a way as to reverse the display (mirror image)?
Thanks,
Zac

[KJSatz]

Well I'd say the main advantages of the OBDuino over the original MPGuino are the ability to read other OBD-II information and that all you have to plug into is the OBD-II port, instead of splicing into a VSS and fuel injector wire. With 2008 cars, you will want to think about warranty implications of MPGuino installation in comparison to OBDuino installation.

[jmilk]

Originally Posted by zwoodward

A final question that our ability to make an HUD hinges on is whether or not the programming for these devices can be written in such a way as to reverse the display (mirror image)?

Fun idea, been thinking about that as well. It's certainly possible to mirror the custom large-number display of the MPGuino. But having worked with various character LCD modules (like the one used here) in the past, I don't think the LCD's backlight would provide the right combination of brightness and contrast to make a workable HUD. For that, you might want to adapt a 7-segment display -- and yes, they can be mirrored: There are a few i2c led-controllers out there which can control the display on the segment-level, and only use two arduino pins.

[Magister]

Originally Posted by zwoodward

Is the OBDuino a project a newbie could tackle?

It depends, if you know how to solder and follow a schematic, you can do it. The arduino/LCD is easy to connect. My CAN interface using the ELM327 looks like this:

and it's made based on this schematic:

Originally Posted by zwoodward

I've been trying to follow this thread and am unsure if someone actually has a working version of the OBDuino in a CAN car?

I think I am the only one who has one, and yes it's working for a few month now, the code is very mature and stable. I tested it in my car (Elantra 07) and a rental car (Pontiac G5 08), both worked without tweaking or doing anything other than plug the OBD2 plug.

[cmags]

I think its time for me to try this out - looks like this has come far enough. I never really go the chance to look into any of the programming myself with other things at home and work taking the majority of my time, but I really appreciate the work you guys have put into this. I'll hardly have the time even to solder something up and program via copy/paste, so hopefully I'll find a few hours soon to try this out.

I'm in an ISO car, with a MAP intake. Looking at the code it looks like the OBDuino automatically converts MAP to MAF (approx) if the MAF PID request doesn't return expected data. So If i'm understanding properly, all I have to do is comment out the #define ELM and I should be good to use the following schematic:



Correct?

[Magister]

Yup, the ISO hardware interface never worked in my car (it's CAN only) so I never really tested the ISO part software that init/read/write but it should word.

[trebuchet03]

Originally Posted by cmags

I think its time for me to try this out - looks like this has come far enough. I never really go the chance to look into any of the programming myself with other things at home and work taking the majority of my time, but I really appreciate the work you guys have put into this. I'll hardly have the time even to solder something up and program via copy/paste, so hopefully I'll find a few hours soon to try this out.

I'm in an ISO car, with a MAP intake. Looking at the code it looks like the OBDuino automatically converts MAP to MAF (approx) if the MAF PID request doesn't return expected data. So If i'm understanding properly, all I have to do is comment out the #define ELM and I should be good to use the following schematic:



Correct?

Are you using the mc33290 chip and if so, where did you find it? It looks like digikey no longer stocks it, but they link to a MCZ33290EFR2 equivalent (I think, without looking too closely, it's just RoHS compliant). I think I'm going to order a few of these if this is the right piece.

[cmags]

Originally Posted by trebuchet03

Are you using the mc33290 chip and if so, where did you find it? It looks like digikey no longer stocks it, but they link to a MCZ33290EFR2 equivalent (I think, without looking too closely, it's just RoHS compliant). I think I'm going to order a few of these if this is the right piece.

Yes it should be the equivalent, but you can get them for the perfect price direct from Freescale (Free sample of up to 2):

MC33290 Product Summary Page

[trebuchet03]

Originally Posted by cmags

Yes it should be the equivalent, but you can get them for the perfect price direct from Freescale (Free sample of up to 2):

MC33290 Product Summary Page

OR-dered Thanks