The ReadColorSensor function reads the color currently being 'seen' by the NXT color sensor. (Note: brick firmware 1.28 or greater is required for this function)

The input parameter should be an NXT input port number between 1 and 4 (which the color sensor is plugged into).

The mode parameter should be one of the following values:

• “ColorDetect”
• “LightSense”
• “RedSense”
• “GreenSense”
• “BlueSense”

If the mode ColorDetect is chosen, then the returned values will be a number between 1 and 6 which represent the following colors: black, blue, green, yellow, red, white.

You can use the ToColorName function to convert from these six values to a color name

If any of the other modes are chosen, then the result will be a color intensity value between 0 and 1023.

val = nxt.ReadColorSensor( input, mode );

function OnStart()
{
  nxt = app.CreateNxt();
  app.SetMenu( "Connect,Sense Color" );
}
 
function OnMenu( name )
{
  if( name=="Connect" )
    nxt.ShowDevices();
 
  else if( name=="Sense Color" )
  {
    clr = nxt.ReadColorSensor( 3, "ColorDetect" );
    app.ShowPopup( nxt.ToColorName( clr ) );
  }
}