I'm looking for some not too expensive, easy to control color graphics LCD I can use for various hobby projects, along with an AVR microcontroller or maybe an ARM in the future. The cheaper the better, but I want to be able to either control it with a serial connection, or a low-speed parallel connection. Some LCDs require multiple MHz parallel control signals to drive each pixel individually, I probably can't manage that with a single AVR. This unfortunately rules out super cheap LCDs like replacement Nintendo DS LCDs or whatever. Recommendations on LCDs that you've personally used & liked will be especially appreciated. Thanks.
Electronic – Easily controlled color LCD for hobby projects
avrdisplaylcd
Related Solutions
The problem with using a microcontroller to drive an LCD is that an LCD requires constant attention. This can be mitigated with a CPLD driven over SPI (using DMA, of course), but then you run into the other problem: Color LCDs require a lot of data. 320x240 in black and white is marginal at 9.6KB, but make it 24 bit color and suddenly you need to deliver 230KB of data in 1/60th of a second. (Don't forget, though, that you can get 4-bit, 16-color control just by tieing the low 20 bits to one setting). A 24-bit frame buffer no longer fits in onboard RAM on most microcontrollers, and you probably don't have time to read from an external RAM chip, clock the data out, and still do other processing. Trying to do this with a CPLD (or an FPGA) and a RAM chip gets you well over the $2 price that caused you to balk in your question.
The traditional solution to interfacing a microcontroller with a color LCD is a display controller like an SSD1963. Here's a very simple block diagram:
Parallel input to a big RAM frame buffer (Translation: More than $2) interfaced with a register-configurable parallel LCD interface. The parallel input is usually compatible with a memory bus interface.
The color LCD market is not always easy to find on the web, usually being the domain of OEMs only, with the rest buying displays from companies who integrate the controller with the display. The best resource I've found has been Crystal Fontz, specifically this page on choosing graphic LCDs. Scroll to the bottom for the controllers, which include the following options (note: Not all are color controllers):
- Epson S1D13521B01 E Ink Broadsheet (1 module)
- Epson S1D13700 (11 modules)
- Epson SED1520 Compatible (8 modules)
- Himax HX8345 Compatible (1 module)
- ILITek ILI9325 Compatible (3 modules)
- KS0107/KS0108 Compatible (26 modules)
- Novatek NT7534 (14 modules)
- Orise Technology OTM2201A (1 module)
- Orise Technology SPFD5420A (1 module)
- RAiO RA8835 (1 module)
- Sanyo LC7981 (13 modules)
- Sino Wealth SH1101A (2 modules)
- Sitronix ST7920 (29 modules)
- Solomon SSD1303 (1 module)
- Solomon SSD1305 (9 modules)
- Solomon SSD1325 (2 modules)
- Solomon SSD1332 (1 module)
- Solomon SSD2119 (2 modules)
- ST STV8105 (1 module)
- Toshiba T6963 (23 modules)
By itself, an LCD being color or monochrome doesn't affect power consumption. Color LCDs are just monochrome LCDs with filters on the pixels to make them red, green, or blue. What will affect power consumption is:
- Is the display backlit, and if so, how bright? Even a small LED backlight drawing 10 mA can easily overshadow the rest of the power consumed in the display.
- How much computational effort are you using to keep the display refreshed? A high resolution graphical display may drive your system to have a faster processor, more memory, and higher clock speed than it would need for a simple character display. That increased performance comes with increased power consumption.
You have to look at the display options in the context of the system to make a determination of the ultimate effect on battery life.
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Best Answer
This LCD assembly works with serial commands and is only about $35 [USD]. There are other options as well, but even once you get past the command set, interfacing to small LCDs physically is difficult due to the FPC connectors they use. If that is not a problem, you might find more variety with low cost color displays from Newhaven Display International. I've used two of their products so far. Digikey carries some of them, but some seem to have a large minimum order quantity, so you might have to order directly from newhaven.