扫描方式,lcd驱动程序

 

显示器的扫描方式主要有隔行扫描（Interlaced）与逐行扫描（Non-Interlaced）两种，港台地区也称为交错与非交错。隔行扫描是指在显示器在显示图像时，先扫描奇数行，然后再回头扫描偶数行，经过两次扫描才完成一次图像刷新。而逐行扫描则是将视频线条连续进行扫描，一次性刷新图像。逐行扫描方式显示的图像要比隔行扫描稳定和清晰，一般来说，在640*480的分辨率下，几乎所有显示器都为逐行扫描，但在1280*1024或更高的分辨率下，就不是所有显示器都能做到逐行扫描了。市面上有某些15显示器声称可以上到1600*1200的高分辨率，实际上是以隔行扫描方式实现的，通常会标注为1600*1200（I），这个括号里的“I”就是“Interlaced”，隔行扫描

 

先摘抄一份，以备后用

 

前些天调试LCD，发现显示的内容完全是旋转的，并且也只显示了部分，写color bar的程序部分如下

#include <stdio.h>

#include <fcntl.h>

#include <string.h>

#include <stdlib.h>

#include <linux/fb.h>

#include <sys/mman.h>

#include <sys/ioctl.h>

#include <fcntl.h>

#include <malloc.h>

#include <unistd.h>

struct fb_var_screeninfo vinfo;

int main(int argc, char *argv[])

{

int fbfd, fbsize, i;

int red, green, blue;

unsigned char *fbbuf;

if (argc != 5) {

printf("usage: ./%s /dev/fbx r g b/n", argv[0]);

printf("e.g: ./%s /dev/fb0 128 255 255/n", argv[0]);

exit(0);

}

red = atoi(argv[2]);

green = atoi(argv[3]);

blue = atoi(argv[4]);

/* Open video memory */

if ((fbfd = open(argv[1], O_RDWR)) < 0) {

exit(1);

}

/* Get variable display parameters */

if (ioctl(fbfd, FBIOGET_VSCREENINFO, &vinfo)) {

printf("Bad vscreeninfo ioctl/n");

exit(2);

}

printf("xres, yres, pixel/bit : %d, %d, %d/n", vinfo.xres, vinfo.yres, vinfo.

bits_per_pixel);

/* Size of frame buffer */

fbsize = vinfo.xres*vinfo.yres*(vinfo.bits_per_pixel/8);

/* Map video memory */

if ((fbbuf = mmap(0, fbsize, PROT_READ | PROT_WRITE, MAP_SHARED, fbfd, 0)) == (void *) -1

) {

exit(3);

}

/* Clear the screen */

for (i = 0; i < fbsize; i++) {

*(fbbuf + i++) = red;

*(fbbuf + i++) = green;

*(fbbuf + i++) = blue;

}

printf("clear screen with rgb:%s %s %s %d/n", argv[2], argv[3], argv[4], fbsize);

munmap(fbbuf, fbsize);

close(fbfd);

return 0;

}

改进部分如下

unsigned char *bar(unsigned char *base, int width, int height, unsigned char r, unsigned char g, unsigned char b){ register int i; register int n = width*height; register unsigned long pixel; /* RGB8888 */ register unsigned long *p = (unsigned long *)base; pixel = r; pixel <<= 8; pixel |= g; pixel <<= 8; pixel |= b; for(i=0; i < n; i++) *p++ = pixel; return((unsigned char *)p);}ptr = bar(fbbuf,800, 120, 255, 0, 0); /* 800x120 bar of red */ptr = bar(ptr, 800, 120, 0, 255, 0); /* 800x120 bar of blue */ptr = bar(ptr, 800, 120, 0, 0, 255); /* 800x120 bar of green */ptr = bar(ptr, 800, 120, 255, 255, 0); /* 800x120 bar of red/blue */

显示如下

code: 

red

blue

green

red/blue

 

后来发现其实是扫描方式,的问题。

 

 

 

但是应该显示:

 

 

 

red

blue

green

red/blue

 

 

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