sample for in-car OBDII output on 20x4

Telek · 11-20-2002, 02:42 AM

The first one displays information in the following order:

Speed RPM Load_Value
Fuel_Economy Absolute_Throttle_Position Intake_Manifold_Pressure
Coolant_Temp / Intake_Air_Temp Timing_Advance Trip_Duration

The last line indicates that CRUISE control is activated, the fuel system is on a Closed Loop and has a 2% trim and that my average speed is 112km/h

and

What do you guys think? Has anyone else done something like this? These are just samples right now, but I know that all of that data is available from the ECU. I haven't seen any programs that can output OBDII data to a LCD, has anyone seen any?

C4M · 11-20-2002, 03:32 AM

Quote:

Originally posted by Telek
[What do you guys think? Has anyone else done something like this? These are just samples right now, but I know that all of that data is available from the ECU. I haven't seen any programs that can output OBDII data to a LCD, has anyone seen any?

I had a response all thought out, but so I don't offend the people that bug Aaron (you know who you are, you small minded twerps), I shall modify:

JESUS!

That's a whole lot of information! I didn't know that you could pull that much information from OBD II, let alone show it on an LCD! I'd like to see that stuff on my 5.6" rather than an LCD - did you write the interface to pull the data as well, or is that something that is generally available?

Great werk!

C!

Telek · 11-20-2002, 03:37 AM

No, that's just raw text. However I have both the source code to display information on the LCD and the source code to read information from the OBDII port, so it is possible and I will code it together if I need to. I haven't seen anything else to do it to an LCD unfortunately.

If you want to a video LCD, then check out my FAQ, I have listed several pieces of software that can read information and display it realtime on screen.

Loftus · 11-20-2002, 07:47 AM

That looks mint! So did you write the software for it?, if so congrats. Okay you have both the source code to display information on the LCD and the source code to read information from the OBDII port, but does it hook up the same way to the computer through the printer port or comm port? Also what other parts are needed ie: Hardware to hook up to factory computer?
( okay i checked out your site , seems you need the serial controller for $90USD )

I like VW's and i know they use OBDII on the 90's models maybe even still producing them. Anyhow this would be a cool enhancement to anyones ride.

Telek · 11-20-2002, 10:44 AM

You can actually get one for $65USD, or make one yourself, if you're handy with eletronics it doesn't look very difficult, all you essentially have to do is give a com port interface since the OBDII interface is already in "serial" format.

Once I have the unit (it's in the mail... grr....) I'll hook it up and if I can't find anything to do what I want then I'll write the software myself, it shouldn't be that difficult. IF I do then I'll post it somewhere and let you all know

Ivar · 11-23-2002, 08:44 PM

Quote:

Originally posted by Telek
You can actually get one for $65USD

Where?

Telek · 11-24-2002, 04:33 AM

scantool.net (check out my FAQ I have a list of stuff in there)

$69 incl shipping!

But beware: ask them to use USPS with whatever method allows tracking... USPS has lost my last 2 shipments in a row (a watch and now this adapter...) The cheap USPS shipping (while giving $500 insurance automatically) doesn't allow tracking, so on the 4-10 day shipping scale (where I usually get it in about 3-5 days) it's now day 12 and nobody can tell me anything about where it is. (sigh)...

Oh, never, never, never, NEVER ship UPS... ESPECIALLY if it's cross-border. It's bad enough that they literally have either lost or screwed up in one form or another about 1/4 of the shipments routed by them (it was up to 6 of 11 within a 2 month window once!) they have now upped their "Brokerage Fee by RapeU" ... $36 for ANY package that comes cross border that they need to charge duty on. Pay $4 in duty on a $25 item and pay an extra $36 in brokerage fees. It used to be $26 but I guess they decided that it was too difficult for their room-temperature-IQ brokerage handlers so they need to pay them more. Fedex is $7 and USPS is $8...

(end rant... sorry that one really pi$$ed me off)

bh76 · 11-27-2002, 12:40 AM

I wrote a little DOS app to display troublecodes on a Matrix Orbital 20x4 LCD. It just does troublecodes, though. (mode 3 and mode 4)

One of these days I'll get around to adding mode 1 (real time data) support to my tsr, though.

Implementing Speed, RPM, Engine Load, Abs throttle position, intake manifold pressure, intake air temp, timing advance, closed/open loop, and trim should be straight forward since they use the following PIDs
0D,0C,04,11,0B,0F,0E,03,06/07 respectively.

I'm curious about the other data you mentioned: fuel economy, trip duration, and cruise. Can't find any PIDs to match them. Do you plan on using some kind of manufactuter-specific modes and/or PIDs?

Telek · 11-27-2002, 03:09 AM

I think that you have to use MODE 7 (Reports On board monitoring results for continuously monitored systems) to get some of that additional information.

MODE 7 reports on the following systems (if your ECU supports it): Misfire, Fuel System, Components. From the Fuel System you can get the Fuel Injector Pulse Rate. Once you know the specs for the fuel injectors (specifically the flow rate) you have all that you need to calculate your fuel economy. Fuel injector pulse rate is the time (usually in ms) that the fuel injectors are open during each firing. Combining this with the flow rate and RPM and the # of cylenders that you have, you now know how much fuel you are using. Use the current speed that you are going and you now have fuel economy. Use the software to calculate stats based upon this.

I have yet to verify exactly how to do this, but I know that the ECU *can* provide this information. With a professional (~$2000) scan tool you can get the required information out of the ECU, and the ECU has to control and know all of this information anyway so there's no reason why it shouldn't provide it via the OBDII port. Even OBDI can provide most (if not all) of that.

Trip duration is pretty simple to calculate, just watch from the time that the car starts moving (vehicle speed > 0). You can also do things like measure the time spend moving (only add up time when speed > 0), amount of time spent waiting, amount of time spent at different speed intervals, etc, etc. You can also calculate distance travelled for any given trip by watching speed and time.

Additionally you can calculate what gear your car is in (provided that you don't have one of those new elite stepless transmissions)... Since there is a fixed gear ratio you can tell by RPM vs speed what gear you're in. For example, in 5th gear at ~3000 RPM my car is around 120kph. ~3400 is 140kph. There is a direct relation between RPM and speed for any given gear.

Cruise control I actually don't know about. Obviously the ECU has to know this information so it should be able to provide it. I read somewhere that it can, but I can't find ANY information on modes > 4 to verify any of this. I don't know if the scan tool can tell you when cruise is enabled.

I know that you can also send commands to the ECU via the OBDII port but your particular interface might not support this fully. With some cars you can do things like turn on the dome light and unlock a particular door, for example.

Can you send me any/all information you have on OBD/OBDII? I'm trying to figure out everything and what can be done, but good info is pretty hard to come by. I have almost all info for MODE 1 but that's about all.

Thanks!

inline4 · 11-27-2002, 03:55 AM

does obdii tell you your mpg?

Telek · 11-27-2002, 04:44 AM

no, see my above post on how to calculate it though.

smaug · 11-27-2002, 09:19 AM

my god, you my friend have completed my senior design project, sort of..

but yeah, I wanted to take a 20x4 lcd and interface it with obdII on a GM truck, to display information..

does your setup use a computer? or is it just wired up to the connector itself..

please more info!

Thanks!

its been awhile since I've been around here, but I think im gonna have to get back into this.. my 95 blazer has one of the first obdII systems.. computer in the engine comparment, and obdII connector under the dash, hopefully this will work, or else ill be force to work on the pops blazer.

Telek · 11-27-2002, 06:12 PM

yeah I know that I could get a lot of course credit for all of this stuff that I'm doing

It's interfaced via a computer but I'm actually considering changing around my setup... I'll let you guys know more once I do!

MikGan · 11-27-2002, 08:38 PM

Dont mean to sound stupid (but im starting to think thats gonna be unaviodable). But where exactly are yougetting the information from? Are you interfacing to the cars management computer or some other device?

You all talk about the OBCII or something like that, whats that all about. This porject sounds really good, and something I could do easily with my background and programming experiance. But I've got no starting points here.

Give me a lead and a few weeks and I'll show you hows its done

Cheers,
Mik.

Telek · 11-27-2002, 08:51 PM

OBDII is "OnBoard Diagnostics version 2"

It's an interface to the car's ECU (engine control unit aka ECM engine control module) which is the onboard computer. This port allows you to connect to that computer to query information from it, mainly designed for diagnostics assistance. The original OBD ports were ad-hoc standards designed by manufacturers to decrease the amount of time that it took to repair a car because of the growing complexity in the onboard computers. OBDII became a standard due mainly in part to California and their environmental laws... search for OBDII on google and you'll find a few thousand links, all that you ever wanted to know.

what do you want to know about it?