Tonight i spent some time at HAC:Manchester reverse engineering the keyboard matrix on our speak and spell, in preparation for hooking it up to an MBED. Since nobody else has released this information (as far as i can tell), here is the pinout:
| pin | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 |
|---|---|---|---|---|---|---|---|---|
| 1 | u | k | off | a | f | ? | p | z |
| 2 | v | l | go | b | g | & | q | ` |
| 11 | w | m | <- | c | h | ??? | r | # |
| 12 | x | n | " | d | i | :) | s | / |
| 13 | y | o | _ | e | j | on | t | return |
This means that when the 'off' button is pressed, for example, pin 1 and pin 5 will be connected together.
To read a matrix keyboard like this, we write some code that steps through the 'down' set of pins (1, 2, 11, 12, 13), holding them low one at a time, then checks each of the other pins (3-10) to see if anything is being held low. If so, we perform a lookup on the table above.
Code to follow next week!