Programming Potentiometer for Shooter

[nickcvet89]

Originally Posted by Doug Norman

According to eStop Robotics, that board gets read as a joystick input on your robot. For the Joystick Open VI, choose the JoystickDevice input to match the location of your eStop CCI on the Driver Station Setup tab. For example, if your CCI is in location 2 on the DS, then your JoystickDevice input would be USB 2 in the robot code.

There is another alternative you could use. On the I/O tab of the DS, when it is set to Compatible Mode, you will see Analog Input sliders. You could read these instead of an external potentiometer. In this case you would read the values on the robot using the WPI Robotics Library>>DriverStation>>Compatibility I/O>>WPI_DriverStationGet Analog Input.vi. Then you would scale it accordingly to drive your motor.

Would the analog input(like a potentiometer) then act as a joystick and the digital inputs act as buttons on the joystick vi's? That seems to be my understanding.

[nickcvet89]

Ok so I have had success with programming this. Essentially what I did was in Teleop called the joystick vi's like you normally would when you want to do tank drive or other joystick related things and set the axis 1 as the shooting axis. The reason why I choose axis 1 is because on the board the analog inputs it gives you are call X, Y, Z, R. I assumed they all followed the the same in LV. This worked with great success but the problem I have is that when you turn the POT, you have a neutral position(zero position) where the shooter motor is not running and when you turn the knob to one side it goes forward and the other side spins the motor in reverse. Is there any way where I can take the values from from one extreme and use this as my starting position where the motor spins forward and increases the speed as you turn the knob?

[Alan Anderson]

Joystick values range from -1 to +1. You want to run the value through a formula that produces an output from 0 to +1 before you feed that to the motor, right? That's easy: add one, then divide by two.

[nickcvet89]

Originally Posted by Alan Anderson

Joystick values range from -1 to +1. You want to run the value through a formula that produces an output from 0 to +1 before you feed that to the motor, right? That's easy: add one, then divide by two.

Ahh, thanks for this, I completely forgot about adding one and dividing by two.