I want to connect my car's OBD2 port to my arduino, i see many topics about it but i want to use a UNO R4's CAN bus, is it possible?
And i read some articles about some cars don't use can bus but uses another type of communication system and i couldn't find out if my car even uses can bus or anything else.
Yes - eg,
https://www.sparkfun.com/categories/tags/obd-ii
and many more ...
You will find that lots of them are based on the ELM chips
EDIT
It seems thta ELM Electronics are no more:
https://www.elmelectronics.com/
:. and amazon is full of chinese ODB-II dongles, even with wifi. Just get one and try it.
I was thinking about hardwiring other than a adapter.
I think you mean something like this:
I was thinking about hardwiring it to R4's CAN bus
As you're talking Arduino, I was thinking more like this:
Or even a bare ELM chip
Should be possible - I think modern cars all use CAN nowadays (in the early days, there were various different interfaces)
Of course, you'd then be down to implementing CAN and OBD at the hardware & message level - whereas "adaptors" usually give a more "high-level" interface, and take care of the physical connection (which is more than just having "CAN" in the microcontroller) ...
Just to clearify: There is no ELM chip. There is a PIC with some software that made it out by luck 'cause ELM company forgot the copyprotect bit on one batch.