我正在尝试回显连接到我的系统的 LCD 屏幕，以确认设备功能正常。我运行的是 Ubuntu 18.10。
这是 /var/log/Xorg.0.log 内容中的设备：
[ 15.828] (II) config/udev: Adding input device HID TOUCH HID Touch Panel (/dev/input/event4)
[ 15.828] (**) HID TOUCH HID Touch Panel: Applying InputClass "libinput tablet catchall"
[ 15.828] (**) HID TOUCH HID Touch Panel: Applying InputClass "Risintech HID touch device"
[ 15.828] (II) LoadModule: "risintech"
[ 15.829] (II) Loading /usr/lib/xorg/modules/input/risintech_drv.so
[ 15.832] (II) Module risintech: vendor="X.Org Foundation"
[ 15.832] compiled for 1.19.3, module version = 2.10.5
[ 15.832] Module class: X.Org XInput Driver
[ 15.832] ABI class: X.Org XInput driver, version 24.1
[ 15.832] (II) Using input driver 'risintech' for 'HID TOUCH HID Touch Panel'
[ 15.892] (II) systemd-logind: got fd for /dev/input/event4 13:68 fd 42 paused 0
[ 15.892] (**) HID TOUCH HID Touch Panel: always reports core events
[ 15.892] (**) risintech: HID TOUCH HID Touch Panel: Device: "/dev/input/event4"
[ 15.893] (II) Get Defalt Screen Config
[ 15.893] (**) Option "Screen_MaxX1" "4095"
[ 15.893] (**) Option "Screen_MinX1" "1204"
[ 15.893] (**) Option "Screen_MaxY1" "4095"
[ 15.893] (**) Option "Screen_MinY1" "0"
[ 15.893] (**) Option "Screen_MaxX2" "1204"
[ 15.893] (**) Option "Screen_MinX2" "0"
[ 15.893] (**) Option "Screen_MaxY2" "2275"
[ 15.893] (**) Option "Screen_MinY2" "0"
[ 15.899] (II) [1]1204 4095 0 4095
[ 15.899] (II) Init Screen configurtion pass
[ 15.899] (--) risintech: HID TOUCH HID Touch Panel: Vendor 0x1bfd Product 0x1688
[ 15.899] (II) risintech: HID TOUCH HID Touch Panel: Configuring as tablet
[ 15.899] (**) Option "config_info" "udev:/sys/devices/pci0000:00/0000:00:01.3/0000:03:00.0/usb1/1-9/1-9:1.0/0003:1BFD:1688.0002/input/input4/event4"
[ 15.899] (II) XINPUT: Adding extended input device "HID TOUCH HID Touch Panel" (type: TABLET, id 8)
[ 15.899] (II) risintech: HID TOUCH HID Touch Panel: Device Init
[ 15.899] (**) Option "Mode" "absolute"
[ 15.899] (II) risintech: HID TOUCH HID Touch Panel: initialized for absolute axes.
[ 15.899] (**) HID PANEL: Initialize
[ 15.899] (**) HID TOUCH HID Touch Panel: (accel) keeping acceleration scheme 1
[ 15.899] (**) HID TOUCH HID Touch Panel: (accel) acceleration profile 0
[ 15.899] (**) HID TOUCH HID Touch Panel: (accel) acceleration factor: 2.000
[ 15.899] (**) HID TOUCH HID Touch Panel: (accel) acceleration threshold: 4
[ 15.899] (II) risintech: HID TOUCH HID Touch Panel: Device ON
[ 15.900] (II) config/udev: Adding input device HID TOUCH HID Touch Panel (/dev/input/mouse1)
[ 15.900] (II) No input driver specified, ignoring this device.
[ 15.900] (II) This device may have been added with another device file.
从最后几行中我不确定该设备是否正常运行（尽管它似乎是通过在其上使用手写笔实现的）。
为了确认我已经尝试过：
echo "TESTING TESTING TESTING" > /dev/input/event4
然而，当我这样做时，液晶显示屏上什么也没有出现。我是否使用正确的方法将某些内容打印到屏幕上？日志看起来一切正常吗？
这是我尝试让 LCDPROC 在所述 LCD 上渲染的更大问题的一部分。
谢谢
答案1
您正在尝试写入输入设备。
Adding input device HID TOUCH HID Touch Panel (/dev/input/event4)
这是触摸屏吗？如果是这样，则指定的输入实际上可能是针对屏幕上的触摸事件的。
答案2
我从未添加过 USB 面板，因此无法提供太多帮助。
从日志来看，Xorg 似乎发现只有触摸屏输入，没有 LCD 显示。 /dev/input/event4 是通常使用“cat”而不是“echo”检查的输入。
编辑：实际上 cat 可能会显示很多二进制数据，所以最好使用“od”作为“八进制转储”，这样就只得到 ASCII。
od /dev/input/event4