Limit Switches

Reading a Digital Input

Java

C++

Roscpp

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
//import the DigitalInput Library
import com.wpi.first.wpilibj.DigitalInput;

//Create the DigitalInput Object
private DigitalInput input;

//Constuct a new instance
input = new DigitalInput(port);

//Can then use these accssor to get data
input.get(); //Will return true for a high signal and false for a low signal

1
2
3
4
5
6
7
8
//Include the DigitalInput Library
#include "frc/DigitalInput.h"

//Constructors
frc::DigitalInput input{port};

//Use these to access data
input.Get(); //Will return true for a high signal and false for a low signal

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
//Include the DigitalInput Library
#include "DI_ros.h"

int main(int argc, char **argv)
{
   system("/usr/local/frc/bin/frcKillRobot.sh"); //Terminal call to kill the robot manager used for WPILib before running the executable.
   ros::init(argc, argv, "digitalin_node");

   /**
    * Constructors
    * Create the DigitalInput object
    * DI ros threads (publishers and services) will run asynchronously in the background
    */

   ros::NodeHandle nh; //internal reference to the ROS node that the program will use to interact with the ROS system
   VMXPi vmx(true, (uint8_t)50); //realtime bool and the update rate to use for the VMXPi AHRS/IMU interface, default is 50hz within a valid range of 4-200Hz

   DigitalInputROS digital_in(&nh, &vmx, channel);

   digital_in.Get(); //Will return true for a high signal and false for a low signal

   ros::spin(); //ros::spin() will enter a loop, pumping callbacks to obtain the latest sensor data

   return 0;
}

Important

Subscribe to DI topics to access the data being published and write callbacks to pass messages between various processes.