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a073c2f9c1
The lvglterm page still told the reader to pick the input source that matches the hardware, which was the whole thing being removed: it has one physical keyboard variant now, and reads whatever is registered. The hidkbd page pointed at HIDKBD_ENCODED, which no longer exists. What produces that byte stream now is INPUT_KEYBOARD_BYTESTREAM. system/kbd had no page at all. Signed-off-by: Jorge Guzman <jorge.gzm@gmail.com>
113 lines
4.5 KiB
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113 lines
4.5 KiB
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==============================================
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``lvglterm`` LVGL Terminal for NuttShell (NSH)
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==============================================
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LVGL application that runs an interactive NuttShell (NSH) on the display. NSH
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is started with its standard streams redirected through pipes, its output is
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rendered in an LVGL text area, and the input comes from either a touchscreen
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or a keyboard, selected at build time.
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The shared code lives in ``lvglterm.c`` (NSH startup, output rendering, main
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loop); ``lvglterm_touch.c`` and ``lvglterm_kbd.c`` implement the input
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variants.
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Input variants
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==============
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The input source is chosen with the *LVGL Terminal input source* Kconfig
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choice (only one is built at a time).
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On-screen keyboard (touch)
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``CONFIG_EXAMPLES_LVGLTERM_INPUT_TOUCH`` (default). An LVGL keyboard
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widget operated by touch; a command line is typed and submitted with
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Enter. Suits touchscreen boards and keeps the original behaviour.
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.. figure:: lvglterm-touch.png
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:align: center
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:width: 500px
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:alt: LVGL Terminal with the on-screen touch keyboard
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On-screen keyboard (touch) variant
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Physical keyboard
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``CONFIG_EXAMPLES_LVGLTERM_INPUT_KBD``. Keys are read from a keyboard
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registered with ``keyboard_register()`` and streamed to the shell; the
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output fills the whole screen. The Up and Down cursor keys scroll the
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output. Any keyboard works, and the terminal does not need to know which
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kind it is: USB HID, a matrix, the simulator, virtio.
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.. figure:: lvglterm-kbd.png
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:align: center
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:width: 500px
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:alt: LVGL Terminal driven by a matrix keyboard
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Physical keyboard variant, driven by a matrix keyboard
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.. figure:: lvglterm-usb.png
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:align: center
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:width: 500px
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:alt: LVGL Terminal driven by a USB HID keyboard
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The same variant, driven by a USB HID keyboard
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The keyboard defaults to ``CONFIG_EXAMPLES_LVGLTERM_KBD_DEV`` and can be
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overridden at run time by passing the path as the first argument
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(``lvglterm /dev/kbd1``) when more than one keyboard is present. Note that
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the USB HID driver names its devices ``/dev/kbda`` onwards, since they come
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and go as keyboards are plugged in, while the option defaults to
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``/dev/kbd0``.
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The terminal reads ``struct keyboard_event_s`` events unless the kernel was
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built with ``CONFIG_INPUT_KEYBOARD_BYTESTREAM``, in which case it reads the
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byte stream that the keyboard codec defines. That is a property of the build
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rather than of the hardware, so it is not something to configure here.
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Driving the terminal without a keyboard
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---------------------------------------
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Because the terminal reads a keyboard device and does not care which one, it
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can be driven from the serial console with nothing plugged in. Enable
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``CONFIG_UINPUT_KEYBOARD``, which registers a virtual keyboard on
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``/dev/ukeyboard``, and ``CONFIG_SYSTEM_KBD``, which injects into it::
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nsh> lvglterm /dev/ukeyboard &
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nsh> kbd -i /dev/ukeyboard
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Everything typed on the console appears on the display from that point on.
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Forwarding a real keyboard into the same virtual one lets both drive the
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terminal at once, which it cannot do by itself since it opens a single
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device::
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nsh> kbd -i /dev/ukeyboard /dev/kbda &
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Raise ``CONFIG_UINPUT_KEYBOARD_BUFNUMBER`` when doing this. It counts events
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rather than keys, so the default of eight holds four keystrokes, and a
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console hands over a whole line at once.
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Font
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====
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The monospaced terminal font is chosen with the *LVGL Terminal font* choice:
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``CONFIG_EXAMPLES_LVGLTERM_FONT_UNSCII_16`` (default), or the smaller
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``CONFIG_EXAMPLES_LVGLTERM_FONT_UNSCII_8`` for low-resolution displays where
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UNSCII 16 shows too few columns.
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Configuration
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=============
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- ``CONFIG_LIBC_EXECFUNCS=y`` -- ``posix_spawn()`` must be enabled.
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- ``CONFIG_PIPES=y`` -- Pipes must be enabled.
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- ``CONFIG_SYSTEM_NSH=y`` -- the NSH library must be enabled.
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- ``CONFIG_GRAPHICS_LVGL=y`` and ``CONFIG_LV_USE_NUTTX=y`` -- LVGL with its
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NuttX integration.
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- A display (``CONFIG_LV_USE_NUTTX_LCD`` or a framebuffer). Each input variant
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also needs its own driver: a touchscreen
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(``CONFIG_LV_USE_NUTTX_TOUCHSCREEN``) for the touch variant, or
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``CONFIG_INPUT_KEYBOARD`` and a keyboard driver for the physical variant.
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``CONFIG_LIBC_KBDCODEC`` is selected automatically when the build delivers
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the byte stream.
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- The selected font (``CONFIG_LV_FONT_UNSCII_8`` or
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``CONFIG_LV_FONT_UNSCII_16``) is enabled automatically by the font choice.
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Reference: `NuttX RTOS for PinePhone: LVGL Terminal for NSH Shell
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<https://lupyuen.github.io/articles/terminal>`_.
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