AN2641 datasheet(25/37 Pages) STMICROELECTRONICS

Nome de Peças	AN2641

Descrição Electrónicos	Using the color LCD controller

PDF	37 Pages

Scroll/Zoom	100%

Fabricante Electrônico	STMICROELECTRONICS [STMicroelectronics]

Página de início	http://www.st.com

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25 / 37 page

AN2641

Linux frame buffer

Doc ID 14027 Rev 1

25/37

6.3.2

User level application sample

The Figure 15 shows a simple user application that works over the frame buffer API. The

program shows 3 color bands on the screen by operating on /dev/fb0, the frame buffer

device node corresponding to the display.

After opening the frame buffer device node the program gets the fixed screen and variable

screen information. It first deciphers the visible resolutions and the bits per pixel in a

hardware-independent manner using the frame buffer ioctl FBIOGET_VSCREENINFO. This

interface command gleans the display's variable parameters by operating on the

'fb_var_screeninfo' structure.

The command FB_ACTIVATE_FORCE (while put variable screen information) enables the

CLCD. This line is important to activate the CLCD.

The program then goes on to mmap() the frame buffer memory and writes color data on

each constituent pixel bit.

AN2641 Folha de dados(PDF) 25 Page - STMicroelectronics