Changing parameters on the fly?

[mikets]

Originally Posted by wireties

This feature is one of the most productive things about Wind River's setup. Remember that it is 'C' interpreter, not C++. To get your symbols into the symbol table (and thus accessible) in a usable format (not mangled by the C++ compiler), be sure to put them inside a extern "C" clause.

Can you access members of a structure? For example:

in your C++ code:

extern "C" {
    typedef struct _PIDConst
    {
        float Kp;
        float Ki;
        float Kd;
    } PIDConst;
     PIDConst iMyPidGain;
} 

then from the VxWorks shell:
% iMyPidGain.Kp = 0.001

[wireties]

Originally Posted by mikets

Can you access members of a structure?

No - can't do that directly. The interpreter does not have the benefit of things the compiler/preprocessor would know. Constants are also of no use.

If you know the offsets into the structure you can do it manually with the memory modify commands.

HTH

[rbmj]

Wow - I just tried it and it certainly works. Really cool.

If only there was an inverse of c++filt...

The debugger also provides a nice way to do this, but with more complex multithreaded applications debugging's bound to get tricky...

SmartDashboard is the future though. Once they can actually get it working, that is

[pafwl]

We do this all the time. We have many variables that we can adjust all the time.
you can see the code as part of our 2010 code.

http://www.frc272.com/seminar/Archive/.

We call the LCConfig.cpp. You can change the config file, save it via FTP to the Crio, press a button and have it read in to the running code then have it apply the new settings. Once you like them leave it there. The config is read in when we boot up. Very flexible.

[bob.wolff68]

Well - we gave a shot at the interactive input on SmartDashboard with no luck. It all works on a separate computer as we've all noted, but otherwise...sigh. We tried to also put a button on the SmartDashboard so we could interactively click on the button ... no go...

So, SmartDashboard::GetInstance()->GetDouble() doesn't work... so we use GetString() and then sscanf() to turn it into a double.

Also, using Preferences::GetInstance()->PutString() doesn't work, but PutDouble() and PutInt() work just fine.

bob

[virtuald]

You should check out the SendablePIDController, which is part of the SmartDashboard. I'm not sure if it works in C++ because of the double issue... but it works for me in python

And, before there was SmartDashboard, there was WebDMA, which does the same thing as SmartDashboard except with a webserver on your robot.

[jhersh]

Originally Posted by bob.wolff68

Well - we gave a shot at the interactive input on SmartDashboard with no luck. It all works on a separate computer as we've all noted, but otherwise...sigh. We tried to also put a button on the SmartDashboard so we could interactively click on the button ... no go...

So, SmartDashboard::GetInstance()->GetDouble() doesn't work... so we use GetString() and then sscanf() to turn it into a double.

Also, using Preferences::GetInstance()->PutString() doesn't work, but PutDouble() and PutInt() work just fine.

bob

Have you filed trackers for these issues? If they aren't tracked we don't know about them and are less likely to fix them.

http://firstforge.wpi.edu/sf/tracker....wpilib_c_bugs

Thanks,
-Joe

[bob.wolff68]

Joe,
Thanks for the link to the trackers -- I filed 3 for:
- SmartDashboard::GetDouble() doesn't work for interactive data.
- Preferences:utString() doesn't work at all
- SmartDashboard:utInt() graphs/logs an incorrect (huge) value once in a blue moon causing graphs to become unreadable until the errant data-point scrolls off the graph.

Bob Wolff

Originally Posted by jhersh

Have you filed trackers for these issues? If they aren't tracked we don't know about them and are less likely to fix them.

http://firstforge.wpi.edu/sf/tracker....wpilib_c_bugs

Thanks,
-Joe