Electronic – Getting an 8-bit LCD display interface to work

arminterfacelcdtft

I have a LCD which this controller is used with: LCD Single Chip Driver.

I am trying to get it to work with an 8-bit interface, but in my kit I can't find the three pins that are mentioned in the datasheet IM [0-2].

Here are some descriptions: 2.8" TFT LCD.

and here is the socket description of the LCD kit that I have:
Socket description

Now the current interface of the kit that's working is 16-bit.

That's the schematic of the kit: Kit Schematic

2nd Question:

If this is not possible, it's already connected to FSMC 16-bit, is it possible to just send 8-bit data to the data pins by shifting the data? Because I'm trying to get a large double buffer 140*200*2 bytes and that would eat the memory, so if I have an 8-bit interface would it take less memory buffer, so is it OK to just send 8-bit data to LCD even if the interface is 16-bits?

Best Answer

The number of bits in the interface has no bearing on how much memory is required to store the image. For example with the 8 bit interface a 65,536 color pixel is transferred in two bytes, whereas the 16 bit interface only requires a single transfer - but in both cases the data is 16 bits per pixel.

You could store your image as 8 bits per pixel and translate it into 16 bits 'on the fly'. However encoding RGB in 8 bits only allows for 2~3 bits per channel (eg. 3 bits each of Red and Green, 2 bits of Blue), so color images will not be photographic quality. To improve image quality you could index the 8 bit pixel values into a 256 color palette, which only requires an extra 512 bytes of memory for 16 bit color.

Related Solutions

Electronic – Debugging initialization of LCD with NT7605 driver

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);
}

Electronic – Efficient display of simple text/graphics on color LCD by ARM

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:

MCU to RAM buffer and registers, and thence to LCD interface

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

Related Solutions

Electronic – Debugging initialization of LCD with NT7605 driver

Electronic – Efficient display of simple text/graphics on color LCD by ARM

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