Programming 301:�Event Synchronization, Accelerate/Decelerate

Coach Series

LEGO^® Education SPIKE^TM Prime Word Blocks

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v. 3.2.4

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Robot Design: Programming 301

Learning Objectives

• Familiarization with Events and Event Synchronization.
• Programming Acceleration
• Programming Deacceleration

Prerequisites:

Programming 101 – Introduction and Common Practices

Programming 101 – Basic Movement

Programming 201 – Line following, Variables and My Blocks

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Robot Design: Programming 301

Introduction to Events

• Events allow you to run two or more commands or group of commands at the same time.
• For example, if the robot has one or more attachments powered by a motor, Events can power these attachments while the robot is moving to complete a mission.

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DroidBot IV

Two drive motors powered moving the robot forward

Attachment motor powered at the same time

Some issues have been reported using Events in the SPIKE™ App 3.

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Robot Design: Programming 301

Introduction to Events�

• Events can be initiated by sensor values, message broadcast, or when a condition is met.

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Robot Design: Programming 301

Using “when program starts” word blocks

• The “► when program starts” word blocks starts your programs.
• If there are more than one in a project, both sets of code run when the program starts.
• In this example, the robot will move straight for five rotations (motors A+B) while simultaneously running motor C for 2 rotation.

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Robot Design: Programming 301

Using Events Sensors Word Blocks

• Event Sensor blocks can initiate an Event when a set sensor condition is met.
• In this example, the robot continues to moves forward (motors A+B), while powering motor C until the color black is detected on color sensor D.

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Robot Design: Programming 301

Using Event “broadcast” messages�

• Messages can trigger events at any point in the code.
• The broadcast message [message ▼] sends the message and then continues the rest of the code below it.
• The broadcast [message ▼] and wait sends the message and waits for all the code under that when I receive [message ▼] to finish and then continues the code under the broadcast message block.

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Robot Design: Programming 301

Using Event “broadcast” messages

• Event broadcasts allow synchronization of two parallel sets of code.
• In this example the robot moves forward 3 rotations, sends a message, then independently moves motor A until light sensor D reads black and motor B until light sensor E reads black.
• What does this code accomplish?
• Moves robot forward toward black line.
• Independently move motors until corresponding light sensor reads black.
• Aligns the robot to a black line or squaring on a black line.

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Robot Design: Programming 301

Acceleration

• From the Movement group, select and drag the “set movement motors to” word block to the programming canvas and connect to the “when program starts”. Set to robot motors.
• From the Sensors group, select and insert the “reset timer” word block into the program.
• From the Control group, select and insert the “repeat until” word block into the program.

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Robot Design: Programming 301

Acceleration

• From the Operators group, select and insert the “> (greater than)” Boolean block into the “repeat until” loop input.
• From the Sensors group, select and insert the “timer” reporter block into the “>” Boolean block first input. Enter “5” into the second input.
• From the Movement group, select and insert the “set movement speed to [input] %” word block into the program.

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Robot Design: Programming 301

Acceleration

• From the Operators group, select and insert the “* (multiply)” reporter block in the “repeat until” loop.
• From the Sensors group, select and insert the “timer” reporter block into the “*” reporter block first input. Enter “15” into the second input.
• From the Movement group, select and insert the “start movement [🡩]” word block in the “repeat until” loop.

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Robot Design: Programming 301

Acceleration

• From the Control group, select and insert the “stop [all]” word block in the program.
• Set “stop” block to “and exit program”.

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Robot Design: Programming 301

Deceleration

• From the Movement group, select and drag the “set movement motors to” word block to the programming canvas and connect to the “when program starts”. Set to robot motors.
• From the Sensors group, select and insert the “reset timer” word block into the program.
• From the Control group, select and insert the “repeat until” word block into the program.

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Robot Design: Programming 301

Deceleration

• From the Operators group, select and insert the “> (greater than)” Boolean block into the “repeat until” loop input.
• From the Sensors group, select and insert the “timer” reporter block into the “>” Boolean block first input. Enter “5” into the second input.
• From the Movement group, select and insert the “set movement speed to [input] %” word block into the program.

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Robot Design: Programming 301

Deceleration

• From the Operators group, select and insert the “- (subtract)” reporter block in the “repeat until” loop. Enter “60” in the first input.
• From the Operators group, select and insert the “* (multiply)” reporter block in then second input of the ““- (subtract)” reporter block in the “repeat until” loop.
• From the Sensors group, select and insert the “timer” reporter block into the “*” reporter block first input. Enter “10” into the second input.

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Robot Design: Programming 301

Deceleration

• From the Movement group, select and insert the “start movement [🡩]” word block in the “repeat until” loop.
• From the Movement group, select and insert the “stop moving” word block and insert it after the “repeat until” loop.

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Robot Design: Programming 301

Everything is awesome!

-Emmet Joseph Brickowski

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Robot Design: Programming 301