title: How to code in C for Alphanumeric 4x3 keypad
body: <p>Currently I am working on a project which has following setup.</p>
  
  <ol>
  <li>AVR micro-controller</li>
  <li>IDE - AVR Studio</li>
  <li>Operating system - FreeRTOS</li>
  </ol>
  
  <p>For input I am using a keypad matrix of 4x3. I have already coded for 4x3 keypad to take inputs as numbers. But now I want to make it alpha-numeric. Like we see in our mobile phone keypads. </p>
  
  <p>Example - Key 2 will be used to take input for 2,a,b,c. Single press key 2, we will get number 2, double press key 2 then we will get 'a', tripple press key 2 then we will get 'b' and fourtimes press key 2 then we will get 'd' on scree.</p>
  
  <p>I hope all of you understood what I mean above. Can anybody give some code idea in C to implement this type of functionality?</p>