uC and LCD (or uC and LCD controller) interfacing

ali

Have you done web searches?

An LCD segment turns dark (or light) when you apply voltage, and will get stuck that way if the voltage stays on. So an LCD controller applies a square wave to the segments you want to turn on -- that's a big part of the reason you need a controller instead of just logic and some resistors.

Generally you only connect a micro directly to an LCD if the micro has an LCD controller built in.

An LCD controller usually has an interface that makes it look like memory. You write the correct commands and data to it, and it does what you want.

If you are thinking about a text only LCD I have done an interface to the MicroBlaze uC. Find out more from my blog:

Sven

Actually, you can do it with logics and DC/DC converters. I am driving an LCD panel by toggling port pins only, but it's using up all the micro processing power. So, in theory, you can build an LCD controller with standard CPLD, FPGA or ASIC. For high volume, ASIC w/ dumb uC might be cheaper than LCD uC.

Text LCDs have an HD44780 control chip. These are easy to interface, but text is all they can display.

"Dumb" ECM-A0526 640x480 graphic LCD driven by a 48 MHz PIC (and apparently nothing else!):

"Dumb" ECM-A0526 640x480 graphic LCD driven by a PIC, some dynamic ram (DRAM), and a few other chips:

ATmega8 microprocessor driving a semi-intelligent (KS0108 controller chip) PVG120602EGE 128x64 graphic LCD:

AVR CPU driving an intelligent (SED1330 controller chip) graphic LCD:

Lots of LCD code for PIC microprocessors:

Atmega 16 CPU, T6963C intelligent controller:

perhaps a complete solution may suit you:

Don...

-- Don McKenzie

Site Map:

Serial OLED uses standard micro-SD memory cards.

USB Flash Drive interface for existing products.

There are dedicated LCD controllers out there, both big and little. I'm currently using a small graphics LCD panel; the only data sheet I refer to is the one for the driver. That ought to be even cheaper than an ASIC for all but the highest of volumes.

We are currently using the LCD AVR, but $4 @10K is kind of expensive. A dumb AVR is less than $1.5. I think we can add LCD function to an ASIC for less than $1, given that we need an ASIC anyway.