queryOBD received byte id doesn't always match sent about arduino

[franksmicro]

Interesting. It would appear that the OBD is returning speed data without being asked. Maybe when requesting speed data the first time, it returns the response more than once. Or maybe it regularly sends speed data wihout being asked. You don't have any other OBD devices (such as add-on instruments) that would be requesting OBD data, do you?

You could try receiving without sending and seeing if you regularly get speed data and perhaps other data back (if you are curious as to the cause). Regardless, it is probably best to check that the received PID matches. Congratulations on fixing the code to do this. I will test the changes in my car over the next week or so and then add in your changes on github.

Thanks,
Frank

[dcm684]

I saw that you added the check for the PID. In my testing I noticed that my change is not completely optimal. If a bad PID is received and then no data is received, it is possible that the system will have to wait for 5 timeout periods. As a result I put in an extra case to handle a timeout.

noMatch++;
//Change made below
if ((noMatch >= 5) || (rxSuccess = false))
{
    return 0;
}

[franksmicro]

Thanks. I will change it to:

    noMatch++;
    if (!rxSuccess || noMatch >= 5)
    {
        return 0;
    }

Do you want me to put credit to "dcm684" in the code for these two changes?

Frank

On Tue, Jul 12, 2011 at 4:41 PM, dcm684 <
[email protected]>wrote:

I saw that you added the check for the PID. In my testing I noticed that my
change is not completely optimal. If a bad PID is received and then no data
is received, it is possible that the system will have to wait for 5 timeout
periods. As a result I put in an extra case to handle a timeout.

noMatch++;
//Change made below
if ((noMatch >= 5) || (rxSuccess = false))
{
return 0;
}

Reply to this email directly or view it on GitHub:
#1 (comment)

[dcm684]

Frank, that would be great if you attribute those changes to dcm684.