ivan

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  1. ivan

    Nexys3 VGA output

    Hello everyone. I'm currently trying to create simple VGA EDK project to show something on the LCD monitor with Nexys3 board. Nexys3 board has Micron celular RAM and I have a problem that every row is represented by four same rows on the screen. I think that my problem is like problem described on Xilinx Community forum: https://forums.xilinx.com/t5/Embedded-Development-Tools/xps-tft-problem-VGA-displays-repeated-rows/m-p/164338/highlight/true#M19715 I've used PLB bus and tried setting Video Memory on base address of Micron RAM and on high addres - 2 MB. I have also tried to set Video Memory to whole Micron RAM (16 MB). Micron RAM was successfully tested with the SDK built in memory test. For software code, I used example from Xilinx (xtftexample.c). I think that problem is with speed of Micron RAM. I found that in asynchronus mode you need to wait 70 ns for data to be ready. This means that frequency of accessing to Micron RAM is about 14.29 MHz and TFT controller works with clock of 25 MHz. Does anyone have example EDK project which uses Micron RAM in synchronous mode? If you need any information about my project, please let me know. I would appreciate any help.