基于FPGA的非XGA标准图像显示控制器的设计

XGA Display Controller of Non-Standard Image Based on FPGA

针对实际应用中许多相机输出的图像数据格式不符合XGA标准,无法直接进行显示,介绍了一种对该类图像进行标准XGA格式转化的显示控制器。在分析计算的基础上实现对相机的合理控制,使相机的输出行频与XGA标准一致。对于CCD的输出数据通过采用缓冲和时钟切换的技术方法将其转化为符合VGA时序的图像数据。按照VGA标准时序将图像数据输出,从而实现XGA显示。该显示控制器基于FPGA实现,其关键技术在于利用FPGA内部的FIFO实现CCD数据的二级缓冲和时钟变换。一级缓冲为大容量双时钟FIFO,实现时钟的切换和数据的深度缓冲;二级缓冲为单时钟FIFO,其容量为1行,作为行显示缓冲区。该显示控制器同时利用FPGA实现XGA所需的行场同步信号及控制CCD的外行同步信号。文中的非XGA标准图像显示控制器具有实现灵活,时序稳定的优点,可作为其他相类似图像显示的参考。

In practical project, image data of some CCD doesn＇t fit XGA industry standard, so it can＇t be displayed in XGA monitor directly. This paper introduces a XGA display controller of non-standard image. First, CCD is controlled to make its output line frequency fits XGA standard by computing. Second, CCD data is buffered and output clock is switched to make it fit CCD timing requirement. Finally, image data is driven out by XGA timing. The display controller is based on FPGA, whose key point is two level buffer of CCD data and clock switching by FIFO Ram in FPGA. Level 1 buffer is FIFO with big volume and double clock, which is used in depth buffer and clock switching. Level 2 buffer is FIFO of single clock and a line volume, which is used as line buffer. The display controller also generates horizontal and vertical synchronous signal of XGA and external line synchronous signal of CCD. The controller has an advantage of flexible achievement and steady timing, and can be referred by display of similar image.