Electrical – Why exactly do you need a LCD controller board to interface LCD to a microcontroller


I've dealt with interfacing a very simple LCD display with a microcontroller, so I get the basic concepts. I'm trying to interface something a bit more involved.

I'm a bit confused on why you would need a LCD controller board to interface a LCD that displays nothing more than simple characters (no graphics). Take this LCD from Electronic Assembly for example. It has a table of command for the LCD controller SSD1803. Does this mean I cannot interface this LCD screen without a lcd controller board to my microcontroller?

Best Answer

You don't need an external controller for this kind of LCD. This is the controller.

In general, character LCD modules will include the controller, usually with some variation of the Hitachi HD44780 controller, perhaps with a different data interface than the ancient 4/8 bit interface.

Graphic LCD modules, especially color ones, tend to need an external controller with a frame memory. In some cases that may be part of your MCU or FPGA so it can share memory and respond quickly, in other cases there may be a controller as part of the module so it can work with a much more modest micro (at a cost in complexity, dollars and speed). In the former case, the interface is sort of a digital version of a video signal- color digital values refreshed regularly at some frame rate. The pixel rate will be beyond the ability of a small micro to handle even if it did nothing else.