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The following picture shows simplified block diagram of the design. In principle the structure of the design is the same of the one described in [[AN-BELK-004:_Interfacing_BoraEVB_to_TFT_LCD_display|AN-BELK-004]].
[[File:An-belk-005-0102.jpgpng|700px]]
LCD is driven by a controller implemented in PL that fetches pixel data from frame buffer and periodically refreshes physical screen. LCD controller provides configuration registers that are mapped in the following address range:
Every pixel on the display has 2 possible states, ON (light pixel) or OFF (dark pixel).On the frame buffer, the memory is mapped with 8bit for pixel. A byte of value 0xFF represents a ON pixel, and all the other values (0xFE to 0x00) represent a OFF pixel.
The following picture shows the block diagram of the Vivado project:
[[File:An-belk-005-02.jpg|800px]]
At the following URL the Vivado design is available for download: TBD. Please note that, even if this application note is based on BELK 2.2.0, this design has been implemented with Vivado 2013.4
==Enabling frame buffer driver in linux kernel==
To enable frame buffer driver user need to:* get the pre-built binaries from TBD Kernel and device tree can also be build with the following procedure:* update Bora kernel repository (as described [[Bora_Embedded_Linux_Kit_(BELK)#Updating_the_repositories_from_BELK_2.1.0_to_BELK_2.2.0|here]])* checkout ''bora-feat-lcd-support'' branch (using ''git checkout bora-feat-lcd-support'' command)* build the updated kernel source as usual Put the binaries on the first (FAT32) partition of your BELK 2.2.0 SD card, overwriting the original one when needed. Please note that you need the following files:* boot.bin* bora.dtb* uImage* fpga.bin* uEnv.txt Insert the SD card into BoraEVB and turn on the board.
During kernel bootstrap, the following messages are printed out on console, indicating framebuffer driver has been loaded succesfully:
Once the kernel has completed boot, frame buffer can be accessed from user space applications via <code>/dev/fb0</code> device file (for more details please refer to https://www.kernel.org/doc/Documentation/fb/framebuffer.txt).
The following image shows a slideshow generated with [http://linuxQt 4.die.net/man/1/feh feh] image viewer ??? demo application running on top of X Window Systemit.
TBD
