Template:S5Pxx18-SPI-2.8TFT

1 Connect SPI 2.8"LCD to S5P4418/S5P6818 Based Board

The following steps only apply to Kernel Linux-4.4. We took the NanoPi Fire3 as an example. Run the following commands to initialize FriendlyElec's 2.8" SPI LCD.

These commands need to be run only once.

sudo mount /dev/mmcblk0p1 /boot
sudo apt-get update
sudo apt-get install device-tree-compiler
sudo fdtput /boot/s5p6818-nanopi3-rev05.dtb spi0/spidev@0 status -t s "disabled"
sudo fdtget /boot/s5p6818-nanopi3-rev05.dtb spi0/spidev@0 status
sudo fdtput /boot/s5p6818-nanopi3-rev05.dtb spi0/fbtft@0 status -t s "okay"
sudo fdtget /boot/s5p6818-nanopi3-rev05.dtb spi0/fbtft@0 status
sudo reboot

Note: the "s5p6818-nanopi3-rev05.dtb" file is the kernel dtb file for the NanoPi Fire3. For another board you need to check its system's "/sys/devices/platform/board/info" file to figure out its dtb file.:

cat /sys/devices/platform/board/info

Here is the info file's content for the NanoPi Fire3:
Hardware  : NANOPI3
Revision  : 0005
Serial  : fa6818dba7110739
The "Hardware" here is "NANOPI3", "Revision" is "0005", "CPU" is "S5P6818", therefore the NanoPi Fire3's kernel dtb file name is "s5p6818-nanopi3-rev05.dtb".

配置完dtb文件，重启开发板后，可以用lsmod命令检查下是否加载了fb_st7789v模块：

lsmod

正常会输出如下内容：
Module Size Used by
fb_st7789v 3315 0
fbtft 31881 1 fb_st7789v

以及用dmesg命令可以查看到SPI屏已经被初始化为fb1设备:

dmesg | grep fb_st7789v

正常会输出如下内容：
[ 6.728000] fb_st7789v: module is from the staging directory, the quality is unknown, you have been warned.
[ 6.908000] graphics fb1: fb_st7789v frame buffer, 320x240, 150 KiB video memory, 4 KiB buffer memory, fps=35, spi0.0 at 50 MHz
接下来要做的事情就比较简单了，无论是运行Qt，还是X-Windows，只需要正确设置Framebuffer设备为fb1即可。

1.1 在2.8寸屏上运行Lubuntu桌面

在 lubuntu desktop系统里执行以下操作:
首先删除armsoc的配置文件：

sudo rm -f /usr/share/X11/xorg.conf.d/20-armsoc.conf

然后新建一个配置文件 /etc/X11/xorg.conf:

sudo vi /etc/X11/xorg.conf

内容如下：

Section "Monitor"
    Identifier          "Primary"
    VendorName          "FriendlyARM"
EndSection
 
Section "Device"
    Identifier          "Primary"
    Driver              "fbdev"
    Option              "fbdev" "/dev/fb1"
EndSection

重启后可以看到图像:

目前暂时不支持触摸屏，可使用鼠标和键盘操作。

1.2 在2.8寸屏上运行Qt程序

在friendly-core系统终端里执行以下命令，运行一个Qt示例:

. setqt5env
export QT_QPA_PLATFORM=linuxfb:fb=/dev/fb1
export QT_QPA_EGLFS_TSLIB=1
export QT_QPA_GENERIC_PLUGINS=tslib,evdevkeyboard
$QTDIR/examples/widgets/widgets/tetrix/tetrix

Qt示例画面如下所示：

目前暂时不支持触摸屏，可使用鼠标和键盘操作。