StephenDone

This thread was previously entitled 'Dashboard Gauge Holder', but I thought I'd better change it...

I am working on a project to build a digital dash display for Imprezas. It will plug into the socket under the dash and will display all sorts of interesting information - a bit like the Techtom unit, but better...hopefully.

You can retrieve all sorts of information via this connector, such as boost pressure, rpm, speed, water temperature, retard due to knock, injector pulse widths etc. If you log the speed data, you can also measure in gear acceleration performance for example.

The snag is that I need to decipher the protocol used between the select monitor and the ecu. I have found out some information, such as pins, voltage levels and baud rate, but must now work out what to send, and what to listen for.

If there is anyone out there with (like me) some reasonable knowledge in both electronics and programming who would like to contribute, please reply back to this thread, and I'll post some more information. btw, if you have a Techtom unit, you could also help greatly.

Fingers crossed.

Steve

Huxley

What a good idea keeps us informed to how it's going.

Thanks Huxley

PSI3

Stephen,
If you need help with Printed Circuit Boards or assembly (SMD and Conventional) contact me (4 directors 2 of us drive scoobs.)


simon

David_Wallis

I dont mind offering what I can... I could possibly sort programming pc side.. and have some knowledge of electronics... but my dad on the other hand is **** hot.. and know d/a a/d convertors inside out and backwards.. I dont mind splicing my loom or clipping scope on... (I have portable scope...) When car is driving...

David

Rob D

Steve,

This sounds a damn good idea.
I've a backround in electronics including a few work colleages.
If you need any help in deciphering anything let me know.

Cheers,

Rob.

kryten

If you need any help/assistance, then keep me in mind. Don't mind helping out, have a low level C/Asm background.

If you stick a terminal emulator on the end, does it spit out data at regular intervals, or is it something that needs prompting from the select monitor?

Nathan L

Sounds like a great idea.

I would love to help but don't even know which end of the soldering iron to use

I make good tea though

Nathan..

StephenDone

Thanks for all the replies - I'm chuffed !

I have put my progress so far on my web site at

PSI3

Steve,
you have mail.

simon.

Scott J Davies

Sounds good

kryten

My ASM skills are mainly PC x86 based, though I can manage others if necessary.

Best thing for decoding/processing the output is probably to get a data log of what's coming out via serial and then write something on a PC to interpret/display the data. Once that's done, connect the PC serial directly to the car and see if it works on a laptop while driving.

I did a yacht autopilot last year and have the code around somewhere to get the data and display stuff that we could probably re-use.

Once this is complete, you can then recode for the microcontroller - the advantage is that changing something on the laptop is far quicker and easier!

Martin J Stirling

Sounds like an amazing idea - I wish I was that clever. Sorry can't help on the electronics side, but I do make a mean sarnie!

Keep up the good work,

MS

David_Wallis

you dont want to know how long it took me to realise that there is a . on the end of the url above!

thats what I get from working 6 - 5 and then working 5 - 8 on scoob... and then 8 - 11 on computer!!

David

StephenDone

<grin>

Hoppy

Stephen, love your site. Very well written and presented. Thanks. Can't think why I've not bumped into it before. Good links too (Chiark etc). It's now on my favourites so I can follow progress

Please keep me posted on developments with your dash display. I've been thinking about some gauges and, the way it's looking, I won't be able to see out of the windscreen for dials.

Sorry I can't offer any help. I have trouble changing a bulb!

A couple of comments on your engine mods. You seem to have failed to keep the car very quiet - no surprise there, I guess - but you've also gone and lost the off-beat throb!!! That is almost a crime and the sound of a throbbing Scoob on full noise is the best tonic after a day's work ever. It's the main reason I wouldn't buy an Evo.

I also read that the unequal-length headers had an advantage in that each pot was giving peak torque at slightly different revs, improving bottom end. Any thoughts?

Thanks again.

Richard.

Houlbt

Stephen..... as I said, I am good with interiors but not electronics.

But, having a good hunt around the internet on thew OBD-II topic, there is a lot of information & I have learnt a fair bit about it.

So, to be clear.... the impreza (MY99/00) is not OBD-II compliant. The impreza RS jobbbie in the US must be though....I thought it was the law over there???? Does that offer any route forward with the problem?

There are a number of products on the market for OBD-II reading. I particularly like the Auterra link, see below. Can you not just devlop some software to run on a product like that?

I mailed a couple of these type companies...and they were all non-commital about there product currently working with a UK Turbo or about being able to supply software to do the job.

NITO

Hi Stephen,

Interesting reading how you get a burst of data and then nothing and then another burst etc. When experimenting with the select monitor the other day there is a few second delay before the information displayed responds. ie..if you blipped the throttle this would show up on the rpm meter a couple of seconds later and not in real time.

Hope thats of help...not sure if its the same with the techtom as I've not tried it yet.

Rgds
Nito

StephenDone

Hi Hoppy,
=========

Thanks for the comments on the site. Let me know if there's anything else I should put up there. Pretty pics of the resonator box going up soon :-) I was a little sad to see my throb go, but not as happy as I was to feel the headaches lift. The manifold _has_ made it much quiter inside the car. Maybe I should record how it sounds and put that up there too.

Hi Tom (Houlbt),
================
Yes, the US Imprezas must be OBD-II compliant, though I guess they are a completely different ECU - all US Imprezas of that time were non-turbo'd. That is part of why the US have only had the normally aspirated cars up 'till now.

The ECU in a 99/00 is made by JECS. The 01-> is made by someone else - can't remember right now who it was, though I'm sure someone will fill me in.

I've tried my car with commercial OBD-II scan tools as well as home grown, and it just doesn't work ;-( The Techtom is the _only_ one I have seen that will talk to my car, apart from a select monitor of course.

>Can you not just devlop some software to
>run on a product like that?
>
The baud rate, serial framing & protocol are different. About the only thing I could pinch from another package is the nice gauge graphics ! Could use the physical interface layer though, since it's the same voltages on the same pin - 7 (ISO-K) 0v/12v.

Hi Nito,
========

The techtom updates very slowly. I think this is on purpose, since LCD displays are very difficult to read if you update them often - the crystals in them are slow to polarise and depolarise, unless you get them nice 'n hot :-)

Try using a select monitor on the 4 point graphing option. In my opinion, it seems to take extremely frequent readings. Maybe they've slowed down the readings if you take a text reading so that it doesn't blur - like the techtom does.

Latest Stuff:
=============

I have a physical interface working - it reads & writes the 0s and 1s onto the right pin. The problem is that I must interface this to my PC. Since I can't tx/rx 8 bit no parity using the serial port tx/rx lines, I need to make up an adaptor cable so that I can manually wiggle/listen on the other RS-232 lines to produce the output/get the input. Sorry guys, I haven't done anything this weekend, since I'm also trying to finish the new online graphing for dyno.scoobynet. I've been spreading myself a bit thin !

Cheers

Steve

z80

Steve,

This is weird. I'm designing a unit to display outside air temp, turbo boost and possibly intercooler air output temp for my P1. I'm basing the design on a Phillips 80c552 microcontroller and I'm writing the code in C. I'm an electronic engineer by profession. I was arranging the unit to have some SRAM to data log the parameters and write some VB code to allow the data to be downloaded from the unit.

The display unit is to be mounted in a display console that Graham Goode advertise for £99.00 - the blank fascia version. The display I will use would be a 2 line back lit Hitachi type LCD display. The lower line will show a row of bars to represent boost. I use a MAX232 to convert TTL outputs from the microcontroller to RS232 levels for the serial port connection.

Perhaps we could get together on this somehow. The difference between your project and mine is that I won't be tapping into an existing wiring loom but will be using a pressure transducer from SPA design £55 (up to 16 Bar, generating a 0 - 5V output) and this will be read by the 80C552's internal 12 bit a/d converter to read in pressure. The transducer is coupled into one of the hoses in the manifild using a short flexible hose. The temperature measurement is to be solved by an LM35CZ 3 terminal device that can again be read by another channel on the microcontroller.

If you need to contact me, please use my e-mail address hybrid_pi@hotmail.com

Best Regards,


Simon Deakin

StephenDone

Hang on, 80C552 is 8051 compatible isn't it ?
I am using 80535/80537 Siemens derivatives of the same chip.

Coincidence or what !!!

Definitely stay in touch. Please use this thread to update us with your progress.

Cheers

Steve

PSI3

Steve,
This might be of some use.

StephenDone

I have added extra info, plus some ECU traces to my web site. If you feel like having a go at decoding any of them, be my guest !

Anthony King

Stephen,
I also had a good look through your web site and was mega impressed. Was very interested in your impressions of the equal length manifold. I would also be interested in hearing how it sounds now.

StephenDone

Maidenhead or Brentford ?

Steve

AndrewC

Does anyone know how different the MY98 OBD is?

I already have a laptop based MP3 player running in my car and I was wonder if it would be possible to read the diag socket via rs232 and record/display this sort of info (the MP3 player already has a 2*16 HD44780 display driven by the parallel port).

Andrew...

Andrew...

StephenDone

Have a look at this URL...

AndrewC

Stephen,

Thanks for the link, I will check if my ECU is compatible, if so then the info on that page could be very useful.

Andrew...

igratton

Don't know if this is any use to you but I tried something like this a little while ago.

It seems that the data comes back from the port in 3 byte packets. The first byte is a descriptor for the ECU code, and the second 2 bytes are HI/LO values for the specific ECU code. The table below shows some of the conversions of the 2 byte pairs based upon ECU code... maybe it will help....

let me know how you get on.


Data Converstion
----------------


SAE J1979 mode 01 continuious data


Request Return
PID DESC byte 1 byte 2
00 PID supported(01-20) xxxxxxxx xxxxxxxx
01 Number of DTC xxxxxxx-
01 MIL ON -------1
01 MIL OFF -------0
01 Misfire support -------x
01 Fuel support ------x-
01 Component support -----0--
01 Reserved ----x---
01 Misfire status ---x----
01 Fuel status --x-----
01 Component status -x------
01 Reserved status 0-------
02
03 open loop 1-------
03 closed loop -1------
03 open loop driving --1-----
03 open loop fault ---1----
03 closed loop fault ----1---
03 reserved -----0--
03 reserved ------0-
03 reserved -------0
04 load % b/255*100
05 coolant temp. F (b-40)*1.8+32
06 short fuel trim b/128*100-100
07 long fuel trim 1 b/128*100-100
08 short fuel trim 2 b/128*100-100
09 long fuel trim 2 b/128*100-100
0A fuel pres. psi b*3*0.14504
0B intake pres. inHg b*0.29613
0C engine rpm (b<<8+b2)/4
0D vehicle speed mph b*0.6214
0E ignition time (b-128)*0.5
0F intake air F (b-40)*1.8+32
10 air flow 1b/min (b<<8+b2)*0.132275
11 throttle % b/255*100
12 air upstream cat 1-------
12 air downstream cat -1------
12 air off --1-----
12 air reserved ---00000
13 O2 location 11 1xxxxxxx
13 O2 location 12 x1xxxxxx
13 O2 location 13 xx1xxxxx
13 O2 location 14 xxx1xxxx
13 O2 location 21 xxxx1xxx
13 O2 location 22 xxxxx1xx
13 O2 location 23 xxxxxx1x
13 O2 location 24 xxxxxxx1
14 shrt fuel trim 11 b/128*100-100
14 shrt fuel trim NA 11111111
14 O2 V 11 b*0.005
15 shrt fuel trim 12 b/128*100-100
15 shrt fuel trim NA 11111111
15 O2 V 12 b*0.005
16 shrt fuel trim 13 b/128*100-100
16 shrt fuel trim NA 11111111
16 O2 V 13 b*0.005
17 shrt fuel trim 14 b/128*100-100
17 shrt fuel trim NA 11111111
17 O2 V 14 b*0.005
18 shrt fuel trim 21 b/128*100-100
18 shrt fuel trim NA 11111111
18 O2 V 21 b*0.005
19 shrt fuel trim 22 b/128*100-100
19 shrt fuel trim NA 11111111
19 O2 V 22 b*0.005
1A shrt fuel trim 23 b/128*100-100
1A shrt fuel trim NA 11111111
1A O2 V 23 b*0.005
1B shrt fuel trim 24 b/128*100-100
1B shrt fuel trim NA 11111111
1B O2 V 24 b*0.005
1C OBDII CARB 10000000
1C OBD Fed 01000000
1C OBDII and OBD 11100000
1C OBD I 00100000
1C None 00110000
1D O2 location 11 1xxxxxxx
1D O2 location 12 x1xxxxxx
1D O2 location 21 xx1xxxxx
1D O2 location 22 xxx1xxxx
1D O2 location 31 xxxx1xxx
1D O2 location 32 xxxxx1xx
1D O2 location 41 xxxxxx1x
1D O2 location 42 xxxxxxx1
1E Power take off On 0-------
1E Power take off Off 1-------
1E Auxil input Reserved -0000000


regards

Ian.

StephenDone

Hi Ian,

Thanks for the info. To which model of Impreza is this data related ? I see at the top it says SAEJ1979, which is OBD-II. Is this for the MY01-> ECU ?

Cheers

Steve

igratton

as far as I know they were from a 99-00 type ecu

I don't think the codes will differ as they are not car specific...they are OBD-II codes.

good luck m8

ian