LEGO Mindstorms NXT

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LEGO Mindstorms NXT
SOURCES
Carnegie Mellon Dacta Lego Timothy Friez Miha
Štajdoharmiha.stajdohar_at_fri.uni-lj.si
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Sensors
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Sensors and Motors

• Four sensor ports
• Sonar
• Sound
• Light
• Touch
• Three motor ports
• Each motor includes rotation counter

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Touch Sensors

• Education kit includes two sensors
• Much more robust than old RCX touch sensors

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Light Sensor

• Reports light intensity as percentage
• Two modes
• Active
• Passive
• Practical uses
• Identify intensity on paper
• Identify lit objects in dark room
• Detect shadows

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Sound Sensor

• Analogous to light sensor
• Reports intensity
• Reputed to identify tones
• We have little experimented with this
• Practical uses
• Clap to signal robot

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Ultrasonic (Sonar) Sensor

• Reports distances
• Range about 5 cm to 250 cm
• In practice
• Longer distances result in more missed pings
• Mostly reliable
• Occasionally gets stuck
• Moving to a new location helps in receiving a
  sonar ping

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Using Joysticks

• To control your robot using a joystick axis or a
  button, use these functions
• frcRFport gets the value from a joystick
  axis
• port p1_y, p1_x, p1_wheel, p2_x,p3_x, etc.
• frcOIJoystickButtonsport
• port oiButtonPort1Button1 through
  oiButtonPort4Button4

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Using Loops

• A Loop will help a portion of your code execute
  repeatedly, until told to stop.
• while(true true)
• motorport1 frcRFp1_y
• motorport2 frcRFp2_y
• This code will cause the motors to respond to the
  joystick values forever.
• The loop reads (while true is equal to true)

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Analog Sensors

• Very easy to read analog sensor values
• SensorValueport
• port in1,in2,in3 in16
• while(SensorValuein1 lt 10)
• motorport1 frcRFp1_y
• motorport2 frcRFp2_y
• This program will run until an analog sensor on
  port 1 sees a value of less than 10.
• Analog sensor values can range from 0 to 1023

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Digital Sensors

• Digital sensors are a little more complex
• First you have to decide if you want the sensor
  port to be an input or output
• frcDigitalIODirectionport condition
• port pio1, pio2, pio3, pio18
• condition dirInput or dirOutput
• Second you have read or assign the value
• frcDigitalIOValueport
• If an input, this will read the value (either a 1
  or 0)
• If an output, you can assign the value using a 1
  or 0.
• frcDigitalIOValueport 1 // turns on the
  digital output port

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ROBOTC for IFI Version 1.14

• New ROBOTC version
• Has built in support for
• encoders,
• accelerometer,
• gyro sensor,
• OI LEDs
• and more!
• Make sure to upgrade!

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IR Board Review

• Rule Clarification from Team Update 3
• 4 Signals Allows
• 4 Signals 4 actions
• Signals must repeat when the same button is
  pressed.

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Operator Interface LEDs

• 11 LEDs installed on Operator Interface
• 7 Green
• 4 Red
• User Controllable with ROBOTC

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Controlling the LEDs

• New ROBOTC function
• frcOILEDsLED true or false
• Examples
• frcOILEDsoiLEDPWM1_Green true
• Turns on PWM1 Green LED
• frcOILEDsoiLEDPWM1_Green false
• Turns off PWM1 Green LED