33
ROM-3420 User Manual
Chapter 3
S
oftware
Functionality
gpio_direction_input(SABRESD_GPIO8);
gpio_direction_output(SABRESD_GPIO9,
0);
3.8.4
RS232 Initial Code
The RS232 initial code as below. It shows you how to initial COM port.
int
open_port(void)
{
int
fd;
fd=open("/dev/ttymxc1",O_RDWR|O_NOCTTY|O_NDELAY);
if(fd
==
‐
1){
perror("open
error");
}
return(fd);
}
3.8.5
Display Output Setting
3.8.5.1
LVDS Settings
Please set environment in u-boot as below:
setenv
bootargs_base
'setenv
bootargs
console=ttymxc0,115200
enable_wait_mode=off
video=mxcfb1:dev=ldb,1024x768M@60,if=RGB24'
LDB-XGA is an example for the resolution of your LVDS panel. You can input the
actual resolution of your LVDS panel here, such as 800x480, 1024x768, etc. The sys-
tem will accomplish the corresponding parameters automatically.
If the panel has problem to be activated, you may need to check the panel datasheet
to configure the panel related parameters. The LVDS video mode database is stored
in linux-3.0.35/drivers/video/mxc/ldb.c. You can add a new one for your LVDS panel.
static
struct
fb_videomode
ldb_modedb[]
=
{
{
"LDB
‐
XGA",
60,
1024,
768,
15385,
220,
40,
21,
7,
60,
10,
0,
FB_VMODE_NONINTERLACED,
FB_MODE_IS_DETAILED,},
}
The definition of fb_videomode in linux-3.0.35/include/linux/fb.h:
The name field is optional. If you input this value, it can be used in U-Boot environ-
ment settings.
The refresh field is the screen refresh frame rate, such as 60Hz, 70Hz. The resolution
can be filled in the xres & yres fields.
The pixel clock (pixclock) is equaled to
10
12
/(Total horizontal line * Total vertical line *
DCLK
). For example, the total horizontal line is 1344 DCLK, and total vertical number
