topic about OBD implementation using K-line in S12 / MagniV Microcontrollers

about OBD implementation using K-line

vinay — Tue, 01 Apr 2008 16:52:04 GMT

Hello,

I am working on 16 bit MCU s12xDP512, i want to interface an OBD using k line through external world like PC. i am using MC33290 k line serial link interface for connecting to MCU. also i made a unit K line to RS232 convertor. now my total communication like this...

MCU---->MC33290------>k line <-------------> k-line-->MC33290------->RS232---->PC

i am able to do a transmission of messege from MCU to PC throgh above. but i cant receive any messge from PC to my MCU. for displaying and getting a messge i use hyperterminal. and SCI0 communication in MCU.

help in this reguards

about OBD implementation using K-line

vinay — Tue, 08 Apr 2008 17:40:50 GMT

i am referening freescale MC33290 ISO k line serial interface IC for it. after implementing i see that the transmission is OK but as time of sending it get back to IC again. and IC take it as a receive data so in k line i get two data same time as transmit as well as receive.i cant get it sepratelly.

plz help in this reguard

i still waiting for somebody's answer

vinay

Re: about OBD implementation using K-line

colinh — Sat, 12 Apr 2008 06:22:36 GMT

Hi Vinay

If I understand your 2nd email then you are seeing the transmitted character being received - is this correct?

If so then this is simply due to the fact that ISO9141 is a half duplex communications medium, and you will always see your transmitted data coming back through the receiver. In this case you have to manage the 'echo' in software.

Apologies if I am misunderstanding your problem.

Regards
Colin

Re: about OBD implementation using K-line

changebusclock — Thu, 12 Mar 2009 17:05:08 GMT

Hai vinnay,

I am very happy to find one working with the same project as mine...

May I know to how far you have completed this project. I am working on a similar project that will just display the diagnostic details on an lcd screen. I am also using DT512 and mcz33290..

What is ur test vehicle model ?

What are all the pins that are available in ur test vehicle .

Did you use any cable to from ur driver IC to the OBD in the automobile?....

did you make a notice of the previous freescale product mc33199 which has both K line and L line , why did you prefer mcz33290ef,,, any specific reason behind?

If we have L line in the automobile , dont we need a driver IC that has L line output as well?

Re: about OBD implementation using K-line

changebusclock — Wed, 18 Mar 2009 22:07:00 GMT

Should we invert the iso9141 driver IC output from mcz33290ef and give as input to OBD interface in car.

I have seen many circuits online(example:- http://hem.passagen.se/tomasf/obd2/) that are giving transistor's collector input to K and L lines. Does this mean that we have to give inverted signal as input to obd interface of car...