For our project, we put together a device that would allow a blind user to send and receive text messages. It will accept input in Braille and will speak its output aloud.

Braille is a tactile reading system used by the blind. For more information about Braille, visit http://en.wikipedia.org/wiki/Braille

Components Used

• SpeakJet speech synthesizer - http://www.sparkfun.com/datasheets/Components/General/speakjet-usermanual.pdf
• TTS256 SpeakJet Controller - http://www.sparkfun.com/datasheets/Components/General/TTS256_Datasheet_prelim.pdf
• Pololu rs232 Serial breakout board
• Several TAC switches and LEDs
• Enfora GSM Serial Modem

Functionality

When turned on, the device will speak a ready message as well as print it to the serial terminal. If a text message is received, the device will read the message aloud. If the SMS send button is pressed, it will prompt the user for a phone number. When done, the user holds the button down, and the device then prompts the user to enter a message body. After holding the button down again, the message is sent.

Data is entered in braille using the TAC switches, one dot at a time. The LED array displays the current braille cell being built, and the space key advances the cell. This is more akin to the "one handed mode" found on braille notetakers such as the Braille Note or Braille Lite

Problems Encountered/ Future Steps

• AT&T Go Phones lock their SIM cards to the phone by default. I had to go to the store and get it changed specifically!
• The Enfora GSM modem was really difficult to interface with mbed. Even after wiring the serial port as described in past projects, the modem refused to communicate with the mbed, even though botht he mbed and the modem can interface with a PC. I eventually ended up using my PC as a serial bridge between the two.
• The SpeakJet chip turned out to be quite temperamental and we couldn't get it to work properly. It would work perfectly for a time, then stop and make crazy sounds.

Images

These LEDs light up as you press buttons to show you the current Braille cell that's being built. This one is a "6" or an "f", depending on weather you're using numbers or letters.

These buttons are for inputting the braille characters. From top to bottom, they correspond to dots 1 to 6 of the braille cell. The two other buttons are to advance character and initiate sending an SMS.

Code

Main Program

Braille Translation Library