search

iwanders / OBD9141

A class to read an ISO 9141-2 port found in OBD-II ports.
MIT License
227 stars 70 forks source link

Slow init simulator code #31

Closed bonadio closed 3 years ago

bonadio commented 3 years ago

Hello @iwanders first thanks for this great library I am learning a lot with it.

I am developing some code that does Slow Init iso9141-2 and I am using your simulator code. My question is on https://github.com/iwanders/OBD9141/blob/master/src/OBD9141sim.cpp line 213 you compare "this->init_hold_value == 21" but shouldn't that be "this->init_hold_value == 51" because the lib sends 0x33 as init sequence?

Thank you

iwanders commented 3 years ago

Hmm, could be, I thought the 21 was because of the slow 5 baud init here. I thought that was read as 21, but it is a long time since I used the simulator. It's gotten zero attention after I had working hardware and working initialisation code. I wouldn't really use the simulator to help you develop your own slow init to be honest. It's not created for that purpose, it was mostly created such that I could check my own PID reading code, at some point the simulator did behave identical to my car (including the init), but like I said, detecting the 5 baud init may not be 100% reliable.

In the example where I used it here I actually force the initialisation to be true, this allows you to bypass the initialisation and still allows testing hardware (and reading PID values) as if it is connected to a car. The simulator does work well for acting like a car when it comes to reading PID values.

bonadio commented 3 years ago

I could not try the code yet, still working on the transceiver but looked again and seems it should be 204 = binary 11001100.

No problem, thanks for the advice, I will use the simulator code it with care. I will post my results once it works.

Thanks very much

bonadio commented 3 years ago

Hello @iwanders your code is correct the value is 21 I just tried. For some reason I had bit banging in my head and I could not understand how sending 11001100 could be 21, but your code is just counting the number of times the port changes so yes I get 010101 and it is 21.

iwanders commented 3 years ago

Ah, glad you got it figured out @bonadio! Thanks for the update :+1: