DIY PDF Bluetooth foot pedal for Android
Why do this:
There are many directions that someone can go to build/buy something like this , so why bother and why is this worth while ?
I think learning and understanding how things work and why they work or don't keep people in a balanced state , IE ignorance is not good for any one, details are the only path out.
This project keeps my mind into a sample of current electronics/Android development and how new products can change the way we work and think. Also this touches things I can use and do, IE wood work is a something I like to do, electronics is something I find fun and programming/machine building is in my blood somehow. The BT foot pedal is something that is changing how sheet music is read when playing a instrument IE no paper just a tablet and a foot pedal I play there for this is good .
I found this link to a DIY foot pedal project
Bluetooth-page-turner-pedal-for-sheet-music-apps . It was a good project to find the
bluefruit-ez-key which gave me the rest of my project as I built everything around it.
Designing the pedal:
I always start with the minimum of what I need:
- Some kind of platform to rest the foot on to trigger a switch/page turn.
- Some kind of switch ?
- Power the unit ?
- Some way to package the hole unit ?
Since most of this project will be built with the Bluefruit-ez-key unit most of the questions and design points will be answered there. Some key features of the EZ-key:
- Power the module with 3-16VDC, so a 9V battery will work great.
- Acts just like a BT keyboard, IE plug a switch to a key and it works.
- Sends the 4 arrow keys, return, space, etc.
It looks like all I need is a platform to hold switches and a box to hold the EZ-key and a 9V battery. I start with the platform, some major points :
- Comfort , I don't want to be picking the foot up to hit a page turn, I wanted something to use as a foot rest and then rotate the foot left or right.
- Back and forward keys will be closest and I wanted a home and end function key to act as a top of document and end of document.
- Pitch of the pedal would be not too high and not too low so again minimal foot movement.
- Size of unit should be small to be able to easily pack away in a gig bag.
- Stability of the unit no tip or chance of turning over during a session.
I wanted a lot of pitch control on the platform so I made this with some scrap wood. Wood is something you can just form into any shape and pitch/angle would be controlled with the supports of the platform. So I started with a shape that would be a arch that would allow the foot to pivot on the heel to each switch. I determined a pitch that was comfortable to rest the foot on and then I cut out the pieces and glued it together.
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| Pitch of the platform for resting the foot |
Because the platform is small and the supports are large there isn't much space to hide a 9V battery and the EZ-key board so a external box was needed to support this, I went with plastic because it is a insulator and it is easy to cut and glue a box also I wanted clear to see the led's on the EZ-key board, again something small/strong. I added and on/off toggle to power on off the unit for convenience.
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| EZ-key , battery, switch |
I wired the box to the platform with some small plastic tie wraps and the wire holes in the foot switch supports. I used monetary stomp box foot switches to do the key presses and wired them to the 4 keys and ground. The keyboard keys I'm using are up arrow for page up, down arrow for page down, space for top and enter for max down, See the EZ-key documentation for the keys and pins .
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| Underside so that you can see supports and wiring |
I wanted to use this on a Android tablet , I have a nook 9 inch with a Cyanogenmod cm11 loaded with Android 4.4.4 . I found the pdf reader
Ebookdroid which has a way to control the scroll down/up and could remap keyboard keys to do functions like top/end to space/return. Ebookdroid is also opensource with alot of functionality in it but the documentation is not much but I was able to figure it out.
There is a bit of
documentation in the EZ-Key unit that I over looked and that is when paring the EZ-Key to a device you have to hit the very small button on the EZ-Key to start the pairing else it will never see it, I wasted some hours of work missing that button.
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| The buttons are mapped right to left as bottom, page down, page up, top. | |
In general this project took months to figure out all the different pieces and to make the decisions on how I wanted it to turn out. There needs to be a top piece to the control box but for now I'm leaving it off for future debugging. In general this is working well , but I am still in testing and will update with more results later.
