A few things stand out about [Vijay]’s braille keypad for smartphones. One is how ergonomic the plans for the final result are, sitting on the back of the smartphone such that you hold the phone much as you often normally would. Another is that it plugs in just like any other USB keyboard. And the last should make any vi user smile — you don’t have to move your fingers to type. You just press combinations of buttons already under your fingers.
It consists of a custom circuit board with an AtMega32U4, a 16 MHz oscillator, a Micro-USB connector and eight pushbutton switches. The AtMega32U4 allows him to use the Arduino HID library. After mapping the braille button combinations to keys, the HID library sends the key values over a USB-OTG cable to the smartphone to be accepted as if they were coming from a normal plug and play keyboard.
We have to give kudos to [Vishay] for testing with blind people experienced with braille. For example, he’s learned that if the user presses [Dots 1 2] for ‘b’ followed by [Dots 1 4] for ‘c’, they prefer to not have to remove their finger from the 1 in between the two characters, for more rapid typing. He also learned that battery management is problematic and that may be why he’s since abandoned the option of communicating over Bluetooth, leaving just USB, and thereby eliminating the need for a battery.
Read Entire Article: http://hackaday.com/2017/06/29/hackaday-prize-entry-a-braille-keypad-for-smartphone/