Beginner here: many questions

  • Anonymous - 2012-05-02

    I'm trying to run the sample sketch at but am having problems.

    OBD_SERIAL_BAUDRATE is not defined in the sketch or OBD.h. Is this baud rate specific to my car (2002 Mazda MX-5)?  What should I set this to? 9600?

    "OBD.h" requires an "integer type" library to run, but I couldn't find this anywhere in the documentation.  I made my own "inttypes.h" to get it to compile, but what library should I be using?

    From the photos it looks like the TX line is Blue and the RX line is Yellow, and they go to the serial pins 1 (TX) and 0(RX)  Can these colors be confirmed?

    Less important question: what is the current draw when the OBDII connector is plugged in, but the car is off (assuming nothing is powered from the regulated 5V lines coming from the connector).  I want to know if it's feasible to leave the connector plugged in when I'm not driving my car.

    From the photos it appears as if there is an internal red LED that is illuminated.  I haven't seen this when I plug my connector in.  Is the LED not present in all connectors?  Does it only illuminate after a serial connection is established?

    Thanks in advance for your help and advice!

    Cheers, Glenn

  • Stanley Huang

    Stanley Huang - 2012-05-04

    I've just released an update for the library. Please try with it and you should have no compiliation issue.

    For missing inttypes.h, I need to confirm whether you are using Arduino 1.0 IDE?

    Blue line is to be connected to Tx pin and and Yellow line to Rx pin on Arduino.

    LED is not present in current version.

  • Anonymous - 2012-05-04

    Thanks for the fast reply and library update!  I was able to make the sample sketch work with your update and a bit of patients.  Not a big issue, but I sometimes have to press reset a couple times for a connection to be made.  I found the inttypes.h library I should have had before… I think I had an older version of Arduino on my laptop that didn't have that library.  Now to get back to coding…. many thanks

  • James

    James - 2012-10-03

    D:\Downloads\Arduino\arduino-1.0.1-windows\arduino-1.0.1\libraries\OBD\OBD.cpp: In member function 'virtual byte COBD::WriteData(const char*)':
    D:\Downloads\Arduino\arduino-1.0.1-windows\arduino-1.0.1\libraries\OBD\OBD.cpp:96: error: invalid conversion from 'const char*' to 'uint8_t'
    D:\Downloads\Arduino\arduino-1.0.1-windows\arduino-1.0.1\libraries\OBD\OBD.cpp:96: error:   initializing argument 1 of 'virtual size_t Serial_::write(uint8_t)'

    Do you happen to know what this is all about? I'm using 1.0.1 Arduino IDE because I have the Leonardo board and it only supports 1.0.1

  • James

    James - 2012-10-03

    I just tried with my Mega 2560 and 1.0 IDE and it works fine. Must be some code change in 1.0.1 IDE.


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