3x3x3 Tap Code Transmitter and Receiver

• Similar to morse code, Tap code is a way to encode text messages on a letter-by-letter basis. The message is transmitted using a series of tap sounds.
• The 3x3x3 tap code is designed as a 3D array as the table code below:

|-------|-------|-----------|
| A|B|C | D|E|F |   G|H|I   |
|-------|-------|-----------|
| J|K|L | M|N|O |   P|Q|R   |
|-------|-------|-----------|
| S|T|U | V|W|X | Y|Z|space |
|-------|-------|-----------|

• Pause length between dimensions: 1
  
• Pause length between letters: 2
  

Transmitter:

• The transmitter is a buzzer that makes a sound when the signal wave is HIGH or 1, and it stops if the signal is LOW or 0 for an interval of time called period.
• Each (.) represents a 10 (one zero) signal.
• Each "pause" is represented by 0 signal.
• So, to transmit the word "Hello" in 3x3x3 tap code, we will send the mesaage below to the buzzer:
  10 0 101010 0 1010 00 10 0 1010 0 1010 00 1010 0 10 0 101010 00 1010 0 10 0 101010 00 1010 0 1010 0 101010 00
  
• For example “HELLO” will be coded as:

. ... ..  . .. ..  .. . ...  .. . ...  .. .. ...  
(   H  )  (   E  ) (   L  )  (   L  )  (   O   )

Circuit

Receiver

On the other side, the receiver which is a digital microphone receives the sound signal and decodes it back to retrieve the message "Hello". There is a low-pass filter applied to the circuit to remove any noise from the readings of the microphone.

Circuit

• Note: the used capcitor is a ceramic capacitor.