Body: <p>I am trying to make a Lego play piano from ev3, where I have connected two arms to a single motor on either side using Lego elements. Both the arms move counterclockwise to one another (if one plays the key then another won't), the problem is that I need one of the arms to double tap on the key without the motor moving 360 degrees. How do I do it? I have used <code>run_time</code>, <code>run_target</code>, and <code>run_angle</code> but nothing seems to work.</p>
  <p><a href="https://i.sstatic.net/Sv4Jz.png" rel="nofollow noreferrer"><img src="https://i.sstatic.net/Sv4Jz.png" alt="this is not the picture of my product but I assembled it by watching this video. Therefore, the assembly is similar" /></a></p>
  <pre><code>#!/usr/bin/env pybricks-micropython
  from pybricks import ev3brick as brick
  from pybricks.ev3devices import *
  from pybricks.ev3devices import (Motor, TouchSensor, ColorSensor, InfraredSensor, UltrasonicSensor, GyroSensor)
  from pybricks.parameters import Port
  from pybricks.tools import wait
  
  # Play a sound.
  brick.sound.beep()
  
  # Initialize a motor at port B.
  test_motora=Motor(Port.A)
  test_motorb = Motor(Port.B) 
  test_motorc = Motor(Port.C)
  test_motord=Motor(Port.D)
  
  test_motord.run_target(500,-180)
  test_motord.run_time(500,2000)
  wait(1000)
  test_motord.run_target(500,0)
  test_motord.run_time(500,2000)
  </code></pre>
  
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2020-01-29T08:35:06.753Z
Comments.Text: If I understand correctly, you can already tap once. What is preventing you from repeating the same movement in order to tap twice?
Comments.UserDisplayName: zovits
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2020-02-06T18:21:28.563Z
Comments.Text: Please [don 't upload code as a picture](https://meta.stackoverflow.com/questions/285551/why-not-upload-images-of-code-on-so-when-asking-a-question/285557).
Comments.UserDisplayName: H. Pauwelyn
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2020-05-18T20:59:42.083Z
Comments.Text: This is actually quite simple. Turn the motor enough degrees for it to touch the key, then use that same number of degrees to turn it back (but with a - before it to specify that it go backwards. After that, turn it that same number of degrees **again** but without the - this time.
Comments.UserDisplayName: mindstormsboi
Tags: <ev3><programming><python><pybricks>
Title: How do I make a single arm double tap a piano key?
UserDisplayName: Bishes Upadhyaya
ThreadText: # How do I make a single arm double tap a piano key?
  
  (Asked by: username_0 on 2020-01-28)
  
  I am trying to make a Lego play piano from ev3, where I have connected two arms to a single motor on either side using Lego elements. Both the arms move counterclockwise to one another (if one plays the key then another won't), the problem is that I need one of the arms to double tap on the key without the motor moving 360 degrees. How do I do it? I have used `run_time`, `run_target`, and `run_angle` but nothing seems to work.
  
  [![this is not the picture of my product but I assembled it by watching this video. Therefore, the assembly is similar](https://i.sstatic.net/Sv4Jz.png)](https://i.sstatic.net/Sv4Jz.png)
  
  ```
  #!/usr/bin/env pybricks-micropython
  from pybricks import ev3brick as brick
  from pybricks.ev3devices import *
  from pybricks.ev3devices import (Motor, TouchSensor, ColorSensor, InfraredSensor, UltrasonicSensor, GyroSensor)
  from pybricks.parameters import Port
  from pybricks.tools import wait
  
  # Play a sound.
  brick.sound.beep()
  
  # Initialize a motor at port B.
  test_motora=Motor(Port.A)
  test_motorb = Motor(Port.B) 
  test_motorc = Motor(Port.C)
  test_motord=Motor(Port.D)
  
  test_motord.run_target(500,-180)
  test_motord.run_time(500,2000)
  wait(1000)
  test_motord.run_target(500,0)
  test_motord.run_time(500,2000)
  
  ```
  
  **Tags:** ev3, programming, python, pybricks
  
  > **Comments:**
  > **username_1**: If I understand correctly, you can already tap once. What is preventing you from repeating the same movement in order to tap twice?  
  > **username_2**: Please [don 't upload code as a picture](https://meta.stackoverflow.com/questions/285551/why-not-upload-images-of-code-on-so-when-asking-a-question/285557).  
  > **username_3**: This is actually quite simple. Turn the motor enough degrees for it to touch the key, then use that same number of degrees to turn it back (but with a - before it to specify that it go backwards. After that, turn it that same number of degrees **again** but without the - this time.  
  
  ---
  
  ## 0 answers
  
  