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smartphone media keyboard

Need to press Play/Pause quickly on your cellphone while listening to music and charging at the same time.

Presentation

Principle

A small USB Consumer device (not a keyboard!) you'd plug on your cellphone and allow to 1) charge it and 2) do basic media function such as Play/Pause, Next, Prev, and Vol+ and Vol- if I feel fancy. The reason is that while I like to work with my music, going next forces me to touch button to see the screen, then touch another tiny tiny button to press Next or Pause. I like to surf through my music to find something that match the mood or the task at hand, so I do that often and that's a (minor) pain. And an excellent pretext to tinker :)

Points of interrest

  • As simple implementation of a media keyboard, very very similar to the Usb Volume Control I made (and works just fine)
  • Implementation

    Bill of materials

    Schematics

    Source code

    
    #define VOL_UP		0xe9
    #define VOL_DOWN	0xea
    #define PLAY_PAUSE 	0xcd
    #define NEXT            0x??
    

    Pictures

    Links

    Helpful sources

  • Apparently one can be OTG slave AND provide power if FIRST it connects the power wires only AND THEN connects the data wires? link
  • Another gentleman with a similar (?) design said he can charge and be OTG link
  • ... and it continues and lead to here after passing through a site that makes me feel good about my website design skills. I include the image schematic here, in case.
  • Inspiration

  • Usb Volume Control is nearly identical, remove the spinning encoder for volume and add 2 buttons. Done.
  • All content on this site is shared under the MIT licence (do what u want, don't sue me, hat tip appreciated)
    electrogeek.cc ~ Formerly known as Kalshagar.wikispaces.com (AlanFromJapan [2009 - 2019])