OBD MPGuino gauge

[rokrokrok]

Dear forum users,

I was quite excited about OBDuino project so I try to establish working system at home.

Description: Arduino Uno, MC33290 chip (from eBay), Arduino LCD shield with buttons (also from eBay), car with ODB2 connector (VW Passat 1.9 TDI, production year 1998 from Europe). All parts are connected in order with this scheme:
opengauge.org/~obduino/diagram/obduino.gif
But without any button connections and without DB9M connector (I directly used three wires and connected them to the ODB2 female connector on the car: ground, ISO K and power wires on pins described here: plxdevices.com/obd/ )

Unfortunately, I stuck at the initialization phase. I use OBDuino32K code (version 198) and I suspect that problem occurs in the void iso_ini(). I receive '0x55' value from car and then '0x08' values for kw1 and kw2. But after the command iso_write_byte(~b) car response is not as expected (b values is not '0xCC' but '0x55'). I am not sure how to check if car really receive '~b' value (if command iso_write_byte(~b) is successful) and why response from car is not '0xCC'. So this is the point where I stuck .

Hope you have some suggestions,
thanks and kind regards,
Rok

[toc]

You really need to see what reply you get from the car (and what car it is). It might not have ODBII implemented.

[rokrokrok]

Dear toc,
thank you for your answer and suggestions.
But I already explain on which car did I try (VW Passat 1.9 TDI, year 1998). It seems that this car is ODB2 compatible and use ISO 9141 protocol:
outilsobdfacile.com/vehicle-list-compatible-obd2.php?brand=volkswagen

I also clearly describe what values I receive from the car. Did you have in mind some other replays from car?

Regards,
Rok

[toc]

I glanced over the more important bits of your post.
What I had in mind was KWP2000 protocol, very similar to ISO9141, but different responses and commands resulting in similar issues.

The ~b is the 'invert' of the byte. Not the actual sent string .

Cars that are ODBII in the US after 1996 aren't everywhere else (I note your location).

0x55 is the init sync byte, could it be that you are reading it and getting the same value twice?
When I was debugging another protocol, I set about doing it in a request reply manner and used the 'duino with my custom program in it to do the init and go so far as the init (writing out to SoftwareSerial every step of the way so I knew I wasn't reading the previous value of 'b" for example).

[rokrokrok]

Dear toc,
today I check more precisely response from the car. All values are in HEX format, ~ means inverse operation.

After initial procedure (sending 33 at 5 bauds) I receive 55 from car and iso_read_byte() returns true. Then I receive 08 (iso_read_byte() returns true) and again 08 (iso_read_byte() returns true). Then Arduino send ~08 to the car (with iso_write_byte() method). After this, car does not respond (iso_read_byte() returns false 'forever').
So I presume that:
1) iso_write_byte() method does not send anything (Is it possible to check (i.e. with voltmeter) if there is some activity on K line when iso_write_byte() method is active? How?).
2) Car is waiting for some other value from Arduino. Which?

Do you have some suggestions?

Maybe this will help: I also connect to the car (VW Passat, 1.9 TDI, 1998) with VAG-COM program (ODB-II compatibility test in the program). Result:
Protocol keyword: $0808, ISO9142-2 ODB-II compatible.

Many thanks and regards,
Rok

[IvanH]

Hi

After connectig to the car, my OBDuiono32k initializing process succesfull, but all PIDs have zero value.
Protokol is ISO 14230 slow, connection by mc33290.

I build simple logic analyzer and connect it to the Rx and Tx pin on processor.
the communication is


OBDuino to ECU 5 bit slow sequnce, switch to 10400 and send
OBDuino to ECU C1 33 F1 81 66
pause 55ms
ECU to OBDuino 55 E9 8F
pause 1sek
OBDuino to ECU C2 33 F1 01 00 E7

after this OBDUino periodicaly repeat the last sequence but ECU dont send answer.

I think this communication is not in order with ISO specification....

Please help me ....


OBDUino work :-)
I rewrited the initialization routine and switched off DTC reading.

[ngoyat]

hiii

i am using obduino32k r203 code with arduino uno, elm327 adapter and 16x2 lcd.

My obduino is able to successfully communicate with my car ecu and all the readings are displayed properly except fuel consumption related readings.

instant fuel consumption showing negative value.

I searched and found diesel consumption is calculated using both MAF and LOAD
and formula will be (maf * GasConst * load/100) /vss.
**GasConst= diesel**
**Load in %**

Kindly tell how correct fuel consumption reading.


and also if possible please tell how to convert fuel consumption to KM/L


Thanks

[marcelroeder]

Hi,
i am trying to use Obduino32k (ISO 9141) in my Mazda Demio, but the init process fails every time. In debug output the lcd prints F!81 81 F7 80. What do i make wrong???

[njakts]

did you tried to disable headers?

[marcelroeder]

sorry for the stupid question, but how i disable headers?