Displaying Bitmap Images Easily on Small Graphic LCDs
Using the MCU as LCD Controller
In systems with relatively fast CPUs and small (quarter VGA or less) LCDs, there is no need for an LCD controller. The microcontroller (MCU) can do the job of the LCD controller on the side, refreshing the display in an interrupt service routine. The MCUs memory is used as video memory.
Advantages of this approach include the following:
– Very fast update of display possible.
– Eliminating the LCD controller (and its external RAM) reduces hardware costs.
– Simplified hardware design.
The disadvantage is that much of the available computation time is used
up. Depending on the MCU, this can be anything between 20 and almost 100 percent; with slower MPUs, it is really not possible at all.