stuck trying to implement Hitechnic Touch Sensor Multiplexer

[timread]

Oh my goodness - division by zero - how did I miss that!
OK - so I've just got to sort out my code to fit the c++ version... Thanks ever so much for your time everyone.

[gloomyandy]

Oh my goodness - division by zero - how did I miss that!

Well it doesn't help that Java calls it an arithmeticException!

All the best

Andy

[lawrie]

When you have your code working reliably, if you separate the MultiTouch class from the test program that uses it, we could add MultiTouch to the next release of leJOS.

[timread]

hi Lawrie,
Works good.
The output is now a boolean array of the state of the switches 1-4:

Code: Select all

import lejos.nxt.*;
/* This programme interprets
 * the output from the Hitechnic Touchsensor Multiplexer.
 * The Multiplexer here is connected to Sensorport 4.
 * The output returned is an array WhichTouch with the states of the 4 switches
 * (1-4) that have been pressed. Implementation of SensorConstants
 * can be found at http://lejos.sourceforge.net/nxt/nxj/tutorial/AdvancedTopics/Advanced_Hardware.htm#13
 * A touch sensor raw outputs 1023 when it is not pressed. Any value less than 600 is interpreted as pressed.
 * timread v1.0 22/01/09
 */

public class MultiTouch implements SensorConstants {
   
   ADSensorPort port; //all this is on the sourceforge lejos tutorial
   public MultiTouch(ADSensorPort port){ //create switch sensorport with raw output
   this.port = port;
   port.setTypeAndMode(TYPE_SWITCH, MODE_RAW);
   }
   
   public static MultiTouch touch = new MultiTouch(SensorPort.S4); // create new MultiTouch sensor on port S4.
   
   public static void main(String[] args) { //the main method
      while (!Button.ENTER.isPressed()){ //making a loop once the orange button is pressed
         boolean [] whichswitch = new boolean[4]; //create 4 element array called whichswitch which holds the state of the switches
         WhichTouch(); //this calls the method that finds out which switch is pressed
      }
   }
   public static boolean[] WhichTouch(){
   
      int value = 1023 - (touch.port.readRawValue()); // this reads the multiplexer raw output
      //the raw data goes from 0-1023
      int switches = 339*value; //next 4 lines setup switches to be evaluated with bitwise operator
      switches/= (1023 - value);
      switches+= 5;
      switches/= 10;
      boolean [] whichswitch = {false,false,false,false}; //create 4 element array all initialised false
      if((switches & 8)==8){   // this is a bitwise operator &
         // - if the 8th bit of switches is a 1 then switch 4 is true (pressed)
         whichswitch[3] = true;
      }
      if((switches & 4)==4){ //test for switch 3
         whichswitch[2] = true;
      }
      if((switches & 2)==2){ //test for switch 2
         whichswitch[1] = true;
      }
      if((switches & 1)==1){ //test for switch 1
         whichswitch[0] = true;
      }
      return whichswitch; //return array of switch states
      }   
   }


[mescalinum]

I like having it in a class which I put in my class library:

Code: Select all

import lejos.nxt.ADSensorPort;
import lejos.nxt.SensorConstants;

public class TouchMuxHT {
   private ADSensorPort port;
   
   public TouchMuxHT(ADSensorPort port) {
      this.port = port;
      port.setTypeAndMode(SensorConstants.TYPE_SWITCH, SensorConstants.MODE_RAW);
   }
   
   public boolean[] readSensor() {
      int val = 1023 - port.readRawValue();
      int sw = (339 * val / (1023 - val) + 5) / 10;
      return new boolean[]{(sw & 1) > 0, (sw & 2) > 0, (sw & 4) > 0, (sw & 8) > 0};
   }
}