Difference between revisions of "VEX2 Sensors Overview"

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(Analog Sensors)
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=== Accelerometer ===
 
=== Accelerometer ===
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[[File:vex_accel.png]]
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<br />
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Returns an analog value between 0 and 4095.  Each Accelerometer Sensor has 3 cables, X, Y, and Z.  The ports you attach them to don't have to be in any particular order ''(however you WILL need to use 3 ports)''.
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<br />
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{|
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  |-
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  |
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<syntaxhighlight lang="ROBOTC">
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#pragma config(Sensor, in1,    xAxis,          sensorAccelerometer)
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#pragma config(Sensor, in2,    yAxis,          sensorAccelerometer)
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#pragma config(Sensor, in3,    zAxis,          sensorAccelerometer)
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//*!!Code automatically generated by 'ROBOTC' configuration wizard              !!*//
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task main
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{
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  int nBiasValues[3];
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  int X_Accel;
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  int Y_Accel;
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  int Z_Accel;
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  wait1Msec(500); // bias values are being calculated
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  /* store the bias values in an array so that they can be 
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  * displayed in the ROBOTC global variables debug window */
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  nBiasValues[0] = SensorBias[xAxis];
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  nBiasValues[1] = SensorBias[yAxis];
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  nBiasValues[2] = SensorBias[zAxis];
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  while(true)
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  {
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    /* also store the actual sensor values so that they can be
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    * easily displayed in the ROBOTC global variables debug window */
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    X_Accel = SensorValue[xAxis];
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    Y_Accel = SensorValue[yAxis];
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    Z_Accel = SensorValue[zAxis];
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    wait1Msec(100);
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  }
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}
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</syntaxhighlight>
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  |-
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  |}
 
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Revision as of 19:03, 15 February 2012

Main >> CORTEX >> Sensors Overview


For ROBOTC CORTEX Sensor functions, check out the CORTEX Sensor Functions page!

The VEX 2.0 Cortex is equipped with 20 sensor ports. There are 8 Analog Sensor Ports and 12 Digital Sensor Ports. Note that unlike the VEX - PIC microcontroller, all Analog sensors must be in Analog ports, while all Digital sensors must be in Digital ports.

There are a variety of functions and variables used for configuring these ports and accessing their values.

Configuring sensors can be complicated. ROBOTC has a built-in wizard that can be used to configure the VEX 2.0 Cortex sensors. The wizard contains a number of PC windows that allow you to set the following fields for the sensor:

  • The variable name that you want to assign to the sensor. Using a name like “leftBumper” makes for a more readable program than 'dgtl3'!
  • The port that the sensor is connected to.
  • The type of sensor – touch, quadrature encoder, sonar, line follower, etc.



Analog Sensors

There are 5 main types of Analog Sensors for the VEX CORTEX:

Light

Vex light sensor.png
The Light sensor, also known as the Reflection sensor, returns values ranging between 0 and 4095. 0 is the lightest reading and 4095 is the darkest.

#pragma config(Sensor, in1,    lightSensor,    sensorReflection)
//*!!Code automatically generated by 'ROBOTC' configuration wizard               !!*//
 
task main
{
  wait1Msec(2000);                // wait 2 seconds before exectuing following code
  bMotorReflected[port2] = true;  // reflects direction of motor on port 2
 
  while(true)                     // infinite loop:
  {
    clearLCDLine(0);                                // clear the top VEX LCD line
    clearLCDLine(1);                                // clear the bottom VEX LCD line
 
    setLCDPosition(0,0);                            // set the VEX LCD cursor the first line, first space
    displayNextLCDString("Light Sensor:");          // display "Light Sensor:" on the top line
 
    setLCDPosition(1,0);                            // set the VEX LCD cursor the second line, first space
    displayNextLCDNumber(SensorValue(lightSensor)); // display the reading of the lightSensor sensor
 
    wait1Msec(50);                                  // wait 50 milliseconds to help display properly
  }
}

Potentiometer

Vex pot.png
Returns an analog value between 0 and 4095 (although mechanical stops my limit the values to between 5 and 4092).

#pragma config(Sensor, in1,    potentiometer,  sensorPotentiometer)
//*!!Code automatically generated by 'ROBOTC' configuration wizard               !!*//
 
task main
{
  wait1Msec(2000);                // wait 2 seconds before exectuing following code
  bMotorReflected[port2] = true;  // reflects direction of motor on port 2
 
  while(true)                     // infinite loop:
  {
    clearLCDLine(0);                                  // clear the top VEX LCD line
    clearLCDLine(1);                                  // clear the bottom VEX LCD line
 
    setLCDPosition(0,0);                              // set the VEX LCD cursor the first line, first space
    displayNextLCDString("Potentiometer:");           // display "Potentiometer:" on the top line
 
    setLCDPosition(1,0);                              // set the VEX LCD cursor the second line, first space
    displayNextLCDNumber(SensorValue(potentiometer)); // display the reading of the potentiometer sensor
 
    wait1Msec(50);                                    // wait 50 milliseconds to help display properly
  }
}

Line Follower

Vex linefollower.png
Returns values ranging between 0 and 4095. 0 is the lightest reading and 4095 is the darkest.

#pragma config(Sensor, in1,    lineFollower,   sensorLineFollower)
//*!!Code automatically generated by 'ROBOTC' configuration wizard               !!*//
 
task main
{
  wait1Msec(2000);                // wait 2 seconds before exectuing following code
  bMotorReflected[port2] = true;  // reflects direction of motor on port 2
 
  while(true)                     // infinite loop:
  {
    if(SensorValue(lineFollower) < 950) // if the lineFollower sensor reads a value less than 950:
    {
      // turn left:
      motor[port2] = 50;  // motor on port 2 is run at power level 50
      motor[port3] = 0;   // motor on port 3 is stopped at power level 0
    }
    else  // lineFollower sensor reads a value greater than or equal to 950:
    {
      motor[port2] = 0;   // motor on port 2 is stopped at power level 0
      motor[port3] = 50;  // motor on port 3 is run at power level 50
    }
  }
}

Gyro

Accelerometer

Vex accel.png
Returns an analog value between 0 and 4095. Each Accelerometer Sensor has 3 cables, X, Y, and Z. The ports you attach them to don't have to be in any particular order (however you WILL need to use 3 ports).

#pragma config(Sensor, in1,    xAxis,          sensorAccelerometer)
#pragma config(Sensor, in2,    yAxis,          sensorAccelerometer)
#pragma config(Sensor, in3,    zAxis,          sensorAccelerometer)
//*!!Code automatically generated by 'ROBOTC' configuration wizard               !!*//
 
task main
{
  int nBiasValues[3];
 
  int X_Accel;
  int Y_Accel;
  int Z_Accel;
 
  wait1Msec(500); // bias values are being calculated
 
  /* store the bias values in an array so that they can be  
   * displayed in the ROBOTC global variables debug window */
  nBiasValues[0] = SensorBias[xAxis];
  nBiasValues[1] = SensorBias[yAxis];
  nBiasValues[2] = SensorBias[zAxis];
 
  while(true)
  {
    /* also store the actual sensor values so that they can be
     * easily displayed in the ROBOTC global variables debug window */
    X_Accel = SensorValue[xAxis];
    Y_Accel = SensorValue[yAxis];
    Z_Accel = SensorValue[zAxis];
 
    wait1Msec(100);
  }
}