I am writing an essay about LCDs. None of the websites I've used mention anything about the dates and eras that newer technologies were used in LCDs, so wondering, does anyone know whether TFT is still being used in LCDs these days?
Electronic – Do new LCD TVs have TFT
historylcd
Related Solutions
Oh, duh, I didn't read your code carefully -- your send SendLcdByte is wrong:
void SendLcdByte( unsigned char command_0_or_data_1, unsigned char command)
{
SendLcdUpperNibble( command_0_or_data_1, command);
// send the lower nibble next
// AS WRITTEN:
P1OUT = (command & 0x0F) | (P1OUT & 0xF0);
// SHOULD BE:
P1OUT = ((command & 0x0F) << 4) | (P1OUT & 0xF0);
Strobe( command_0_or_data_1);
}
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)
Best Answer
The majority of LCD displays made today use one or more TFTs per pixel. For displays over a certain resolution (probably > 640 by 480 pixels) like TVs or smartphones TFT driving is necessary. When displays were smaller than that so-called passive matrix addressing was possible. You might still see smaller displays that do not use TFT - say a monochrome display in a remote control.
Note that OLED technology (the main competitor) of LCD technology also use TFTs in the pixels.