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Page history last edited by Kai Yu Tan 7 years, 2 months ago

Project Design









Initial Paper prototype





Mouser leds for volume indicator

Oval 2 Oval 3 Oval 4

Infra-red sensor

Infra-red sensor

Voltage shifter






List of Electrical Components Required:


  • On/Off button

  • 3 LEDs

  • A volume LED indicator

  • Resistors for LEDs.

  • 2 infra-red sensors

  • A LCD screen

  • A demultiplexer

  • A voltage shifter

  • A SD card reader

  • An audio jack


List of Materials Required:


  • Wood(Balsa or Durond)

  • Plastc(preferably transparent)

































Key Challenges And Alternative Designs


Possible challenge 1:

Sensitivity of infra-red sensors to the different lighting condition and the plastic material places on top of them for aesthetic reasons.



Do not use any plastic material to cover the top of the detector region

Recalibrate the sensor readings thresholds for different lighting condition


Possible challenge 2:

Problem with timing issue. There might be infinite loop of from one state to another due to fast response of program relative to human hand movement speed.



Use interrupt handler function for detection of signal to pause, play, go tot the next song or back to the previous song



Possible challenge 3:

Not enough pins for all the LEDS or LEDS might affect the light sensor reading



Use a demultiplexer or incorporate some of the LEDS functions into the LCD screen. So instead of having a LED indicator for pause/play/next/back, print the current command or state of the mp3 player to the LCD screen.


Put LEDs away from the sensor zone.



Possible Challenge 4:

Difficulty in coding to differentiate the difference between a change in sensor reading due to the hovering of hand at different height for differerent volume and a change in sensor reading due to the removal of hand once the desired volume is being set



Use a sensor as a reference. So if the reference sensor is activated, the other sensor will be used to detect the height of the hovering. And when the reference sensor is not activated, it will ignore the change in sensor reading in the other sensor due to the removal of hand. (The user needs to coordinate the hand movement which requires a few practices only)






Project Timeline:



Prototyping circuit for non-mp3 parts.

Experiment with light sensor and write codes to detect various hand motions for different command to be executed by the mp3 player

Experiment with different plastic material to be put in front of the light sensor

Link LEDs and LCD to circuit.




Build a rough prototype of housing

Link audio decoder and loudspeaker to circuit.

Add on the code to play the music



Start perfboarding part by part.

Doing unit testing for each part

Build housing for the mp3 player



8/8 onwards:

Final troubleshooting and fine tuning of hand motion detection code

Beautify MP3 box


























Comments (1)

David S said

at 9:52 am on Aug 20, 2013

✓ This is good work, although if portions of it were completed after your project, then you won't have received the advantages that they could provide in project planning and scoping. Still good to see.

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