Switch Block

Use this block to choose between two sequences of code. For example, when configured with a touch sensor, the switch block might run one series of blocks when the sensor is pressed and another when the touch sensor is not.

Display settings

Adding blocks to the Switch block

Moving the Switch block

Configuring the Switch block

Display settings:

1. This icon indicates the sensor or other condition that will cause the block to choose between the two rows of programming blocks. In this case the current status of a touch sensor will cause the program to switch.
2. The upper blocks will run if the touch sensor is pressed.
3. The lower block will run if the touch sensor is not being pressed.

 

1. If you’ve chosen to control the Switch block using the Value condition, a data wire plug will appear at the bottom of the leading edge of the Switch block; you will have to attach a logic or number data wire to this plug from some other block to control the switch.

 

1. By de-selecting the “Display Flat View” checkbox, the Switch block will use a tabbed interface to show the alternative sequences of programming blocks. By clicking on a tab, you will be able to view and edit the blocks and see which condition will cause those particular blocks to run.

Adding blocks to the Switch block:

Add blocks by dragging them over the empty spaces within the Switch block’s surrounding frame. The Switch block’s interior will expand so the block can fit and snap into place. If there are already blocks within the frame, drag any additional blocks over the desired connection point on the sequence beam and the adjacent blocks will shift sideways allowing the new blocks to snap into place.

Moving the Switch block:

The Switch block can only be selected and moved by clicking on the block itself; clicking on the surrounding frame or on the blocks inside the frame will not work.

Configuring the Switch block:

The Control property pull-down menu will let you choose from two primary conditions that will affect your loop:

• Value
• Sensor (which will activate a second pull-down menu)
  • Touch Sensor
  • Light Sensor
  • Sound Sensor
  • Ultrasonic Sensor
  • NXT Buttons
  • Built-in Rotation Sensor
  • Timer
  • Receive Message
     

    LEGO MINDSTORMS Education NXT Software

  • Touch* Sensor
  • Light* Sensor
  • Rotation* Sensor
  • Temperature* Sensor

Value

A Switch block set to “Value” can accept either logic or number input through a data wire connected to its leading edge. It will detect the kind of data wire attached to its plug (i.e., logic or number) and offer different switching options for each.

If you connect a logic (true/false) data wire, the program will run the programming blocks on the upper sequence beam when the Switch block is receiving a “true” signal. If the block is receiving a “false” signal, the program will run the blocks on the lower sequence beam.

If you connect a number or a text data wire, you can specify the exact input that will cause the programming blocks on the different sequence beams to run. Furthermore, if the Display Flat View option is de-selected, you can switch to more than two sets of programming blocks.

1. This field will show the type of input detected by the block.
2. By de-selecting the “Display Flat View” checkbox, the Switch block will use a tabbed interface to show the alternative sequences of programming blocks. By clicking on a tab, you’ll be able to view and edit the blocks and see what condition will cause those particular blocks to run.
3. Each row in the table represents a switching option. When “Display Flat View” is checked, the upper most option, number 1, represents the condition that will cause the programming blocks on the upper sequence beam to run. The second option, number 2, represents the condition that will cause the blocks on the lower sequence beam to run.

   If a Number or Text data wire is connected to the Switch block and the “Display Flat View” is de-selected (enabling the tabbed interface), you can add additional rows to the table that will control more sequences of blocks as in the image below.

4. This box serves two roles. When the Switch block is set for logic input, this box’s pull-down arrow will let you flop the blocks on the two sequence beams, changing which one group will be activated by a “true” signal. When the Switch block is set for number input, use this box to type in the number that will activate a certain switching option.
5. These buttons will let you add and delete switching options. They are only active when the Flat View is de-selected and a number or text data wire is connected to the Switch block’s input plug.
6. The “*” button will set the default option in the list. When the Switch block is set for number data and a signal arrives that does not match one of the set numerical options, the block will run whichever option is set as the default.

Touch Sensor

Choose this control property if you want the condition of a touch sensor to determine which way your program will switch.

1. By de-selecting the “Display Flat View” checkbox, the Switch block will use a tabbed interface to show the alternative sequences of programming blocks. By clicking on a tab, you will be able to view and edit the blocks and see which condition will cause those particular blocks to run.
2. Choose the port where your touch sensor is plugged in. By default, the block will be set to port 1 for a touch sensor. You can change this selection if you need to.
3. With the radio buttons you can specify which touch sensor condition (Pressed, Released, or Bumped) will cause the Switch block to run the blocks in the upper switch area; the lower switch area will run when no action occurs. If you choose Pressed, the block will switch at the instant the touch sensor is pressed in. If you choose Released, the block will switch at the instant the touch sensor is released. If you choose Bumped, the block will switch at the instant the touch sensor is bumped.

Sound Sensor

Choose this control property if you want the readings from a sound sensor to determine which way your program will switch.

1. By de-selecting the “Display Flat View” checkbox, the Switch block will use a tabbed interface to show the alternative sequences of programming blocks. By clicking on a tab, you will be able to view and edit the blocks and see which condition will cause those particular blocks to run.
2. Choose the port where your sound sensor is plugged in. By default, the block will be set to port 2 for a sound sensor. You can change this selection if you need to.
3. Use the slider to set the trigger value or type a value directly into the input box. At the default setting of 50%, the program will run the programming blocks on the upper sequence beam if the sound sensor detects sound levels above 50% and run the blocks on the lower sequence beam if the sound level is less than 50%.

Light Sensor

Choose this control property if you want the readings from a light sensor to determine which way your program will switch.

1. By de-selecting the “Display Flat View” checkbox, the Switch block will use a tabbed interface to show the alternative sequences of programming blocks. By clicking on a tab, you will be able to view and edit the blocks and see which condition will cause those particular blocks to run.
2. Choose the port where your light sensor is plugged in. By default, the block will be set to port 3 for a light sensor. You can change this selection if you need to.
3. Use the slider to set the trigger value or type a value directly into the input box. At the default setting of 50%, the program will run the programming blocks on the upper sequence beam if the light sensor detects light levels above 50% and run the blocks on the lower sequence beam if the light level is less than 50%.
4. If you check the “Generated Light” checkbox, the light sensor will turn on its own small light source and detect this light if it is reflected back to it.
5. The feedback box displays the current light reading (0-100%).

Ultrasonic Sensor

Choose this control property if you want the distance readings from an ultrasonic sensor to determine which way your program will switch.

1. By de-selecting the “Display Flat View” checkbox, the Switch block will use a tabbed interface to show the alternative sequences of programming blocks. By clicking on a tab, you will be able to view and edit the blocks and see which condition will cause those particular blocks to run.
2. Choose the port where your ultrasonic sensor is plugged in. By default, the block will be set to port 4 for an ultrasonic sensor. You can change this selection if you need to.
3. Use the slider to set the trigger value or type a value directly into the input box. At the default setting of 50 (127), the program will run the programming blocks on the upper sequence beam if the ultrasonic sensor detects an object at farther than 50 inches (127 cm) and run the blocks on the lower sequence beam if it detects an object at less than 50 inches (127 cm).
4. Select to read values in Centimeters or Inches.
5. The feedback box displays the current ultrasonic reading.

NXT Buttons

If you choose “NXT Buttons,” the program will run the programming blocks on the upper sequence beam when the chosen NXT button is bumped, pressed, or released. It will run the blocks on the lower sequence beam when no action occurs.

1. Select which NXT button will send out a “true” signal when activated (and end the loop).
2. Choose Bumped if you want the button to be activated after a quick press and release. Choose Pressed if you want the button to be activated at the instant the button is pressed in. Choose Released if you want the button to be activated at the instant the button is released.

Built-in Rotation Sensor

Choose this control property if you want the number of counted rotations or degrees to determine which way your program will switch.

1. By de-selecting the “Display Flat View” checkbox, the Switch block will use a tabbed interface to show the alternative sequences of programming blocks. By clicking on a tab, you will be able to view and edit the blocks and see which condition will cause those particular blocks to run.
2. If you choose "Reset," the Switch block will read the rotation sensor's value and then reset the sensor's value to zero. If you choose "Read," the sensor's value will not be reset.
3. Choose the port you would like to monitor.
4. Use the radio buttons to set the direction you want: forwards or backwards.
5. Choose to count either Rotations or Degrees by using the pull-down menu.
6. Type a value into the input box to set the trigger point. The default value is 360 degrees. At this setting, the program will run the programming blocks on the upper sequence beam if the number of counted degrees is more than 360 and run the blocks on the lower sequence beam if the number of degrees is less than 360.
7. The feedback box will display the current number of rotations or degrees.

Timer

Choose this control property if you want a timer’s current value to determine which way your program will switch.

1. By de-selecting the “Display Flat View” checkbox, the Switch block will use a tabbed interface to show the alternative sequences of programming blocks. By clicking on a tab, you will be able to view and edit the blocks and see which condition will cause those particular blocks to run.
2. If you choose "Reset," the Switch block will read a timer's value and then reset the timer to zero. If you choose "Read," the timer will not be reset.
3. Choose which of the NXT’s three timers you would like to monitor.
4. Type a value into the input box to set the trigger point. The default value is 5 seconds. At this setting, the program will run the programming blocks on the upper sequence beam if the current time is more than 5 seconds and run the blocks on the lower sequence beam if the current time is less than 5 seconds.

Receive Message

If you choose “Receive Message,” the program will run the programming blocks on the upper sequence beam when a certain Bluetooth message is received. It will run the blocks on the lower sequence beam if the message is not received.

1. The pull-down menu will let you select the message type (Text, Number, or Logic) of the message that you expect to receive.
2. To compare the incoming message to a test message, either type in the test text or number (if you have chosen Text or Number respectively as the format), or use the radio buttons to choose the test logic value (true or false). If any incoming message matches the test message or value, the program will run the blocks on the upper sequence beam. Otherwise, the blocks on the lower sequence beam will run.
3. Choose the message number where the incoming message will arrive.

Touch* Sensor

Choose this control property if you want the condition of a touch* sensor to determine which way your program will switch.

1. By de-selecting the “Display Flat View” checkbox, the Switch block will use a tabbed interface to show the alternative sequences of programming blocks. By clicking on a tab, you’ll be able to view and edit the blocks and see what condition will cause those particular blocks to run.
2. Choose the port where your touch sensor is plugged in. By default, the block will be set to port 1 for a touch sensor.
3. With the radio buttons you can specify which touch sensor condition (Pressed, Released, or Bumped) will cause the Switch block to run the blocks in the upper switch area; the lower switch area will run when no action occurs. If you choose Pressed, the block will switch at the instant the touch sensor is pressed in. If you choose Released, the block will switch at the instant the touch sensor is released. If you choose Bumped, the block will switch at the instant the touch sensor is bumped.

Light* Sensor

Choose this control property if you want the readings from a light* sensor to determine which way your program will switch.

1. By de-selecting the “Display Flat View” checkbox, the Switch block will use a tabbed interface to show the alternative sequences of programming blocks. By clicking on a tab, you’ll be able to view and edit the blocks and see what condition will cause those particular blocks to run.
2. Choose the port where your light sensor is plugged in. By default, the block will be set to port 3 for a light sensor. You can change this selection if you need to.
3. Use the slider to set the trigger value or type a value directly into the input box. At the default setting of 50%, the program will run the programming blocks on the upper sequence beam if the light sensor detects light levels above 50% and run the blocks on the lower sequence beam if the light level is less than 50%.
4. The feedback box displays the current light reading (0-100%).

Rotation* Sensor

Choose this control property if you want the number of counted ticks (16 to a rotation) to determine which way your program will switch.

1. By de-selecting the “Display Flat View” checkbox, the Switch block will use a tabbed interface to show the alternative sequences of programming blocks. By clicking on a tab, you’ll be able to view and edit the blocks and see what condition will cause those particular blocks to run.
2. Choose the port you would like to monitor.
3. Use the radio buttons to set the direction you want: forwards or backwards.
4. Type a value into the input box to set the trigger point. The default value is 16 ticks (16 to a rotation). With the pull-down menu set to “>”, the program will run the programming blocks on the upper sequence beam if the number of counted ticks is more than 16 and run the blocks on the lower sequence beam if the number of ticks is less than 16. Setting the pull-down menu to “<” will reverse the above scenario.
5. The feedback box will display the current number of ticks.

Temperature* Sensor

Choose this control property if you want the temperature to determine which way your program will switch.

1. By de-selecting the “Display Flat View” checkbox, the Switch block will use a tabbed interface to show the alternative sequences of programming blocks. By clicking on a tab, you’ll be able to view and edit the blocks and see what condition will cause those particular blocks to run.
2. Choose the port where the temperature sensor is plugged in. By default, the block will be set to port 4 for a temperature sensor. You can change this selection if you need to.
3. Use the slider to set the trigger value or type a value directly into the input box. The default value is 25° C or 77° F. With the pull-down menu set to “>”, the program will run the programming blocks on the upper sequence beam if the temperature is less than 25° C/77° F and run the blocks on the lower sequence beam if the temperature is higher than 25° C/77° F. Setting the pull-down menu to “>” will reverse the above scenario, as will choosing the opposite radio button.
4. Select to read values in Celsius or Fahrenheit.
5. The feedback box displays the current temperature reading.