2. Principle of operation

Basic motion

How is it done?

As it moves from left to right in the air, the LED's are turned ON and OFF in a very rapid sequence at very precise instants. The resulting fast blinking is integrated by the human eye/brain combination, giving the illusion of a line of luminous text.

What happens?

  • The processor wakes up and starts timing the speed of the first swing (a swing is defined as one back and forth motion).
  • At the same time, it retrieves the number of the message selected.
  • It uses this information to initiate the display of a line of characters as follows.
  • The number of characters in the message is counted. This information will be used to allocate to each column of each letter a specific timing.
  • A blank margin is inserted. Its length is adjusted depending on the message length. This will allow each message to be nicely centered, regardless of its length.
  • The first column of the matrix corresponding to the first character is fetched in memory.
  • After a conversion process, the column data is transferred to the LEDs. Some will be ON some will be OFF, depending on the matrix data for that column.
  • The 2 steps above are repeated for the successive columns of the first character.
  • When the first character is completed, an inter-character blank is inserted (all the LED's are turned off). This creates the small blank space placed between each character.
The process above repeat itself for each character of the message.