2. Principle of operation
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.
- 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.