Here you can find samples for Arduino Uno.

You have 8 digit LED display. Digits have such a view:

 ___________________________
/                           \
|      a         Also there |
|     ___        ground pin |
|  f |   |  b    should be. |
|    |___|                  |
|  e | g |  c               |
|    |___|.                 |
|          \                |
|      d    dp (point digit)|
\___________________________/     

Using Arduino IDE, load SAMPLE1.ino on the board. So now you can see algorithm in work. It counts from 0 to 9, then digit point lights on and it goes down from 9 to 0. Reaching 0 loop repeats.

Working idea is similar to SAMPLE1.ino. But we can use serial monitor, which supports commands like :

• pause on - pauses (freezes) the LED display, but the counter continues counting.
• pause off - keeps going (unfreeze) the LED display. It unfreezes with a current counter value.
• delay %time - set time for showing one numeral
• reset
• help - show help dialog

• add new enum value in enum LED_CMD (eg. COMMAND)
• add #define COMMAND_STR "command\0" - max 8 digits
• add #define VALUE_STR "val\0" - max 4 digits
• add declaration and implementation for bool check_COMMAND(Command \*)
• add if(check_COMMAND(cmd)) return; to initCommand
• add case COMMAND: to switch(cmd->led_cmd) in loop()