For children with physical disabilities, using a smartphone is almost impossible. However, they can really gain access to the amazing capabilities of a smartphone with a simple button. For example, see my adaptation for controlling Sphero with a tilt of your head.
This instructable will go over where to buy the button, create the adapter, and use the software to take advantage of this assistive technology.
Note: This adaptation will only work for an Android phone with a microphone line-in.
Step 1: Bill of Materials
1) Assistive Button $35
1) Assistive Buttons $10
2) Female Mono/Stereo Audio Jack 1/8" $3.19
3) Male 4 Conductor TRRS Audio Plug 1/8" $6
4) 4 wires, No Matter Length $0-$10
5) 100-100k ohm resitor $1 (RadioShack)
2) Soldering Iron
How to Save Money:
The second link for the assistive button is much cheaper. The first link is simply the top of the line, very durable and sensitive button, perfect for children with complex disabilities. Hence, why it is so expensive. A simple CD switch will suffice as well.
Also, you can use any wire you have around the house. Just make sure the gauge is small enough to solder to a small audio jack. And you can use any size resistor, it just needs to limit the current for the microphone.
Borrow a soldering iron and solder from a friend.
Step 2: Assembly
The schematic for the adapter is shown in the figures attached to this step. VR is the right channel audio wire, and WL is the left channel. R is the resistor. Vsw(+) is the input to the button (sleeve) and Vsw(-) is the output, or tip. These are all shown in the figures attached to this step.
If you cannot read a schematic well, the pictures with the colored wires may help! Black is ground, white is microphone, grey is right channel, and purple is left channel.
After everything is soldered together, I used a hot glue gun to strengthen the connection. Also, I put electrical tape over the exposed wires for a better look. I chose electrical tape instead of shrink wrap to be able to trouble shoot better.
Step 3: Software Test
If not, here are some trouble shooting tips:
1) Make sure your Android phone has no media audio effects on. Go to Settings -> Sound -> Media Audio Effects -> Wired Connection -> Disable Audio Effects.
2) You actually have a microphone line in to your phone
3) Media Volume is 100%
Post a comment if you cannot get it working, and I'll see if I can help.