Data sent from the SmartDashboard to the cRio

[Hjelstrom]

We have written a custom 'StaticWidget' extension for the smart dashboard which is attempting to send some data from the dashboard to the robot. We're trying to use some code like this in our widget:

// Plug our values right into the robot's network table
NetworkTable table = Robot.getTable();
table.putInt("987IntValue", integer_value);
table.putDouble("987DoubleValue",double_value);

I see other controls doing this such as 'CheckBox', etc. Our widget seems to be working in the dashboard.

My question is, what C++ API can we use to read those values on the cRio side? I was expecting something like SmartDashboard::Get... But I don't see anything like that.

[dkearle]

Originally Posted by Hjelstrom

My question is, what C++ API can we use to read those values on the cRio side? I was expecting something like SmartDashboard::Get... But I don't see anything like that.

I'm not sure if this will be helpful since we are not specifically getting data from the NetworkTable (yet), but we are using SmartDashboard::GetData() in an attempt to get the PID control constants from the SmartDashboard using the SendablePIDController object and corresponding SmartDashboard widget. To use GetData() we did have to downcast the return from SmartDashboard::GetData() from the base class SmartDashboardData to the subclass SendablePIDController. We used dynamic_class < SendablePIDController * > to downcast the returned object.

We are testing this to confirm it works as expected, but ran into a separate problem of disabling our robot when we hit [ENTER] after typing the new value we wanted for the P constant on the SmartDashboard. We'd love to know how to enter data into the SmartDashboard widgets without actually hitting the [ENTER] key on the driver station!

[Hjelstrom]

Thats strange, I'm looking at the WPILib C++ source in FirstForge and I don't see a GetData function call anywhere in SmartDashboard or its parent classes.

[dkearle]

Originally Posted by Hjelstrom

Thats strange, I'm looking at the WPILib C++ source in FirstForge and I don't see a GetData function call anywhere in SmartDashboard or its parent classes.

For documentation I've been using the "C++ HTML Help file reference document" available on FirstForge. This has been incredibly useful. If you haven't already, I highly encourage you to download it - http://firstforge.wpi.edu/sf/go/doc1198?nav=1

After you download, open this help file, select "Contents", "Class List" and then scroll down to the SmartDashboard class. Select this and then scroll down the documentation on the SmartDashboard to the list of "Public Member Functions". GetData() is the third function listed.

I just looked in the SmartDashboard.h file on my computer. It is what was provided when I reinstalled the development environment this year. Here is what it contains: "SmartDashboardData* GetData(const char *keyName);"

[Hjelstrom]

Oh, there is a lot of stuff in there that I don't see in the code I downloaded from FirstForge. Yes it looks like everything we need is there. Thanks!

I was trying to do some research from home where I don't have the development environment. I thought the code in FirstForge would be the latest but it apparently isn't.

Here is where I was looking:
http://firstforge.wpi.edu/sf/scm/do/...cts.wpilib/scm

[Joe Ross]

Last I looked, the source in firstforge svn wasn't updated this year. Look at the source installed on your computer.

[dkearle]

Joe Ross is correct. I just confirmed again that the repository you were looking in hasn't been updated in over 12 months. The HTML help file I mentioned does seem up-to-date and I found it to be very helpful.

[Hjelstrom]

Yes, it all makes sense now :-)

Thanks!

[dkearle]

Originally Posted by dkearle

We used dynamic_class < SendablePIDController * > to downcast the returned object.

I just realized I had a typo here. This should have read dynamic_cast < SendablePIDController * > to downcast the returned object.