(T) 6F/16F Cinque/Sei ECU Reader Project

Excellent. All that circuit is is an optoisolated RS232 to TTL level converter, it just changes serial levels to 0-+5vDC, why wouldnt that work?

Did this thread fizzle out? My '99 Punto also uses the 16F ECU and I am interested in linking it to a laptop. I couldn't determine yet whether it is ISO/OBD compliant so DIY projects 'out there' might not be suitable. One clue is the three pin connector near the ECU rather than the current standard "J whatever" plug under the dash.

The stuff 'out there' that I have been considering includes:

1. Any circuit based on the ELM323 chip (ISO OBD to RS232 converter) used with the free Scantool software (Opendiag project).

2. The VAG-COM setup which uses a fairly simple hardware design from Jeff Noxon and VAG-COM software from Ross Tech (free older version for simple hardware with opto-isolators). Designed primarily for Volkswagon/Audi but probably OK for anything that is OBD2 compliant (may suit Mk2 Punto).

3. Vehicle Explorer software for OBD2. Don't know what hardware this is designed to work with. Think it is for a proprietary unit but you will have gathered that I don't want to spend much.

The functionality of software varies from basic interpretation of hex codes spat out by ECU on demand to full blown user-chooser gauges and meters for dynamic imformation, accompanied by data-logging. Not surprisingly, the best stuff isn't free!

Anyway, back to my original point, is anyone still working on this project?

Meanwhile I'll start to digest the mass of information in the 16F technical file that arseofbox has kindly translated (I surmise that was no mean feat, so thank you!).

Cheers,

Red.

Yes the thread has appeared to have died a death.

The ECU is not ALDL\OBD\OBD2 etc. compliant, and can only be accessed using the protocol it is setup for - that being one specifically developed by Magneti Marelli and all data for it is proprietry to them.

The full interfacing protocol is in that document. The FCCUK (Coupé Club) did something similar to what Im proposing (writing software specifically for ECU interrogation)...as the K/L Line software and hardware is very costly and hard to find!

My work on it has slowed to a crawl due to my lack of programming experience (uC, console C and some VB/VB Script).

The interface circuit needs optoisolation between car and computer as a basic prerequisite, and must act purely as a TTL to RS232 level converter. ECU expects TTL levels and the computer gives out RS232...

Can anybody tell me the starting address on the eprom chip of an Spi Sei, of the fuel and ignition maps? I'd be grateful...

I am attempting to build an ECU fault code reader of the Magneti Marelli 16F.ER in my GF '97 cinquecento sporting. I have read the (italian) document describing the communication protocol and built and programmed a microcontroller based interface to initiate communication, switch from 1200 baud to 7812.5 baud and read the codes from RAM and EEPROM.

The reader side of things is ready to go, but I am having difficulties getting details on the electrical specification of the diagnostic interface.

I know pin 1 is the L line, 2 is GND and 3 is the K line. I have read the voltage across K and GND as around 10.9 volts when the ignition is switched on, but whenever I try to connect it to any kind of circuit, i.e. transistor / led arrangement the voltage drops to almost nothing. At least too low to saturate (turn on) the transistor.

Is the K line an open collector / open drain output, i.e. does it need to have pull up resistors attached?

Some diagnostic protocols work at battery voltage (12V) though someone on this forum said that the ECU expects/ produces TTL (5V) signals.

If anyone has any details on the electrical details of this interface I would like to hear from you.

If you have any details or schematics of a working DIY fiat/lancia interface that would be brilliant.

I have the most complex part finished (the reader) already, I just want to know how to connect it to the ECU (in a physical sense).

I am willing to share any information and my designs / code with anyone else out there who is trying to do something similar.

there is a bloke called barnacle on the fccuk message board who builds them for a Coupe, the Coupe uses a similar ECU. He should be able to help

Thanks for that. I had a look and his interface seems to communicate using ISO9414, I don't think the 16F uses this protocol.

Do you know anyone who has been successful in interfacing with the Cinq using home made kit?

As i said, the ECU is similar and I asked him about if it could be adapted to work on a cento and he said yes.

I gave up looking at the idea because my car now runs a megasquirt ECU.

Serial Level to TTL Conversion

Ive seen them before using an optoisolator between the MAX232 and the EEC. I recall the supply was taken from another source (eg the car battery with suitable voltage regulation), and the entire system was referenced to the same earth.

The L line is Tx and K line is Rx. Section 3 of the document details how to do it....would the English conversion help? It says something about ISO4 standard, but Im not sure on the meaning / implicatons of that that.

Id be VERY interested in seeing your code - the entire reason I never continued this was because Im really not a software engineer....

...funny you should say that, I am (a software engineer that is). The software isn't really a problem, I have built a simple PIC system which will listen for the ISO code @ 1200 baud, reply with the initialisation sequence of 0xff 0xaa 0xcc @ 1200 baud and then switch to 7812.5 baud (produced exactly in software). From there it queries the RAM and EEPROM error code registers and then flashes an LED indicating the number of errors found.

This is a simple test rig, once this is up and running I was intending to write a PC application that would display the detailed error information and realtime sensor values.

I am familiar with the MAX232 and I have used it to interface PICs to the serial ports of computers. I prototyped a simple MAX232 setup and connected it to the K line of my ECU, there was no discernible change in the output when the ignition was turned on.

The ISO 4 standard (in terms of electronic communications standards) means nothing to me. Wikipedia defines it as "ISO 4 is an international standard which defines a uniform system for the abbreviation of journal titles", I don't think that's what Fiat use .

Do you have any sources that confirm if the ECU outputs 0-12V on the K line or TTL 0-5V?

Update:

I suspected there may be quite a bit of stray capacitance between GND and my K line, because after switching off the ignition the output seemed to drop to zero in a nice long curve. If there was a big capacitance across GND and K the ECU would have a hard time pulling the output down to zero when it is outputting the ISO code.

So I removed the ECU from the car to eliminate wiring, sensors, the radio, etc and powered it up on the table... Still getting the same output. . Is the ECU faulty???

I will have access to an oscilloscope at the weekend and I will try to get a proper view of what the ECU is putting out on the K line.

Can anyone else get an oscilloscope waveform from the K line of a cinq, so I can compare?

If not even a voltage reading would be better than nothing.

Hi. I'm really quite interested in this also, although my knowledge is pretty limited but I'm keen to give most things a try. I have the circuit diagram from the original diagnostic link designed by barnacle on the fccuk thread, I built it for my old coupe but never got round to using it before the coupe was written off. It's an older version using a max202 chip.

I don't have access to an oscilloscope but will try and check the k-line voltage on my cinq later.


Having read through the more recent work of barncle on the coupe pages, it would be very impressive if someone could produce a product similar in capabilities to his "widget" that displays live ecu readings on a lcd, and also allows data logging to pc and error code reading.

I've attached the converter diagram, if it's any use.

Cheers
Pete

Thanks peteu,

The circuit diagram you have attached does seem to confirm that the ECU outputs TTL levels to the interface. If this is the case then my ECU is doing something strange.

I have definitely obtained a reading of just over 10volts repeatedly, between pin 3 (K) and GND.

I am not sure that the circuit diagram attached though will work as expected, but anyone please feel free to correct me if I am wrong.

AFAIK, the K line is the data output from the ECU - the L line in the data input to the ECU.

The pins on the MAX202 and MAX232, etc are labelled from the perspective of the TTL (the ECU) side of the chip . i.e. T1IN is the TTL input (going towards the MAX chip) for transmission channel 1. T1OUT is the RS232 output of transmission channel 1. R1IN is the RS232 input of reception channel 1 and R1OUT is the TTL output (going to the ECU) of reception channel 1.

That is, whenever the ECU transmits on the K line, the K line is connected to T1IN, the MAX chip converts this to RS232, outputs it on T1OUT and T1OUT is connected to the receive pin on the computer serial port.

In the attached diagram the L line is connected to T2IN, meaning that the ECU should be transmitting on the L line. The K line is connected to R2OUT, indicating that the ECU will receive on the K line.

It is my opinion that these two lines have been mixed up and K should go to T2IN and L to R2OUT. The RS232 side of things looks fine.

Can someone confirm my assumptions about the direction of the K and L lines and the pin assignments for the MAX202/232?

peteu, it would be great if you could check your K line voltage. However, if the output is indeed TTL it would be quite possible to get a reading of 0v with the ignition on, when the K line is idling (not outputing the ISO code).

What I mean to say is you might miss the voltage flickering up to 5V as the ECU outputs the ISO code and then falls back to zero. Make sure you can see the multimeter clearly whenever you turn on the ignition.
If I can get my communications issues cleared up I would be more than happy to start developing a device like barnacle's widget.

I have built several interfaces and can tell you guys that its best to use the MAX232 rather than the opto method, because you need to write s/w to switch control lines for -12v etc.
The output from MAX232 is in the correct phase for driving the immo, but the logic is 0 to 12v so you need to level shift it. IIRC the o/p from ecu is open collect so if you use a 5k pull up it would read +12v on idle and zero v on signal. I dont know the level switching voltage, but obviously if its above 5v operating without a level shifter would give problems.
Simplist solution is to use a non_inverting chip from interface tx pulled up to batt volts. On the rx from ecu use a serial resistor 5k to ttl input to MAx232 and clamp the input pin with a 5v zener.
If I could put a picture on here I could make it more plain.

reddy4bed - Thanks for that. I see what you're getting at. Simply shift up the ttl output from the MAX232 to 0-12V and clamp the K line output from the ECU so that it does not exceed 5V. Have you ever interface to the 16F specifically?

It was my thinking too that the K line would be open collector and drive to GND when active. However I am getting a voltage of 10v across K - GND with the ignition on and no external pull up.

peteu is going to check his K line voltage, can anyone else give it a try so I can determine if it's my ECU that's faulty or it is expected behaviour.

Trying an attachement of an old reliable one.

ps 10v output would be fine, you could always put a 10v zener clamp on the ecu o/p if you are worried.