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Assignment 5 - Yifeng Huang

Page history last edited by Yifeng Frank Huang 10 years, 1 month ago

Plan for a portable MP3 turntable. See diagrams from Yifeng Huang - Assignment 4.

 

Major components:

 

1. Screen

2. Accelerometer

3. Grip (+ pressure sensor)

4. Thumb wheel (+ rotary encoder)

5. Enclosure (probably plastic)

 

Features:

 

1. Real-time adjustment of playing speed/pitch to movements

2. Battery-powered, relatively small

 

Major technology challenges:

 

1. Real-time adjustment of playing speed

  a. MP3 decoder probably has some support for playing speed adjustment

  b. Unsure of whether works for pitch or not

  c. Unsure of range of adjustment

2. Reading sensors

  a. Accelerometer & pressure sensor are analog - have noise

  b. Need to maintain both responsiveness to controls and smooth playing

 

 

Further explanation of control mechanism: there are three major control axes in the player.

  One is the back-forward tilt - this controls the speed of playing. Holding the player parallel to the ground produces normal-speed playing. Tilting the front of the player toward the user speeds up playing. Tilting back slows it down; at some point (about -25 degrees), tilting back further will produce reverse playing.

  Second is the immediate-response axis. This is moving the player rapidly parallel to the ground. The velocity of the player parallel to the ground is mapped directly to the play speed. Think of it as the player is glued on to the record on the record player, and moving the player back and forth moves the record under the needle.

  Third is the grip. This is pressure sensitive, and the harder the user grips the player, the more influence the immediate-response axis has on the system. (The relationship is most likely going to be linear.)

 

 

 

PLAN B player:

 

Similar controls to Plan A player. Lacks grip, retains accelerometer and thumbwheel.

 

 Idea - variable speed player with scratching effects

 Control - tilts in one axis, rapid movement in other; one controls speed, other controls scratching

 (Display, etc. are the same)

 

This is a simpler design because it lacks one control mechanism and also because it removes the major technology challenge - real-time control of the playing. The plan B player only requires high-level, low-speed modification of basic playing parameters - playing speed on the MP3 decoder - and also a few recorded samples of scratching noises which are played back at opportune times.

 

 

 

Timeline (*'s change to x's as tasks are completed)

 

By 5/14/10:

  * Build enclosure

  * Add sensors

  * Basic software for reading inputs

  * Basic support for playing songs

  * Buy parts

By 5/21/10:

  * Finalize software framework - menus, song selection, using the thumbwheel, etc.

  * Begin work on variable-speed playing

  * Possibly write software on computer for song pre-processing

  * Basic demo for MakerFaire?

By 5/28/10:

  * Continue work on real-time playing adjustment

  * By this time, should have determined whether this technological challenge is feasible to overcome

By 6/2/10:

  * Bugfixes

  * Make up a presentation for class

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