lvglterm LVGL Terminal for NuttShell (NSH)

LVGL application that runs an interactive NuttShell (NSH) on the display. NSH is started with its standard streams redirected through pipes, its output is rendered in an LVGL text area, and the input comes from one of three sources selected at build time.

The shared code lives in lvglterm.c (NSH startup, output rendering, main loop); lvglterm_touch.c and lvglterm_kbd.c implement the input variants.

Input variants

The input source is chosen with the LVGL Terminal input source Kconfig choice (only one is built at a time). The physical-keyboard options differ in the data the keyboard device returns on read(), so the one that matches the hardware must be selected.

On-screen keyboard (touch)

CONFIG_EXAMPLES_LVGLTERM_INPUT_TOUCH (default). An LVGL keyboard widget operated by touch; a command line is typed and submitted with Enter. Suits touchscreen boards and keeps the original behaviour.

LVGL Terminal with the on-screen touch keyboard

On-screen keyboard (touch) variant

Matrix / upper-half keyboard

CONFIG_EXAMPLES_LVGLTERM_INPUT_KBD_MATRIX. struct keyboard_event_s events are read from a keyboard registered through the CONFIG_INPUT_KEYBOARD upper half (for example the M5Stack Cardputer matrix keyboard on /dev/kbd0) and streamed to the shell; the output fills the whole screen. The Fn Up/Down cursor keys scroll the output.

LVGL Terminal driven by a matrix keyboard

Matrix / upper-half keyboard variant

USB HID keyboard

CONFIG_EXAMPLES_LVGLTERM_INPUT_KBD_USB. A USB HID keyboard (for example on /dev/kbda with CONFIG_USBHOST_HIDKBD) delivers a byte stream that is decoded with the keyboard codec and streamed to the shell. When the driver is built with CONFIG_HIDKBD_ENCODED the Up/Down cursor keys scroll the terminal.

LVGL Terminal driven by a USB HID keyboard

USB HID keyboard variant

Both keyboard variants default the device to CONFIG_EXAMPLES_LVGLTERM_KBD_DEV (/dev/kbd0 for the matrix keyboard, /dev/kbda for USB) and can be overridden at run time by passing the path as the first argument (lvglterm /dev/kbd1) when more than one keyboard is present.

Font

The monospaced terminal font is chosen with the LVGL Terminal font choice: CONFIG_EXAMPLES_LVGLTERM_FONT_UNSCII_16 (default), or the smaller CONFIG_EXAMPLES_LVGLTERM_FONT_UNSCII_8 for low-resolution displays where UNSCII 16 shows too few columns.

Configuration

  • CONFIG_LIBC_EXECFUNCS=y – posix_spawn() must be enabled.

  • CONFIG_PIPES=y – Pipes must be enabled.

  • CONFIG_SYSTEM_NSH=y – the NSH library must be enabled.

  • CONFIG_GRAPHICS_LVGL=y and CONFIG_LV_USE_NUTTX=y – LVGL with its NuttX integration.

  • A display (CONFIG_LV_USE_NUTTX_LCD or a framebuffer). Each input variant also needs its own driver: a touchscreen (CONFIG_LV_USE_NUTTX_TOUCHSCREEN) for the touch variant, CONFIG_INPUT_KEYBOARD for the matrix variant, or CONFIG_USBHOST_HIDKBD for the USB variant. The USB variant selects CONFIG_LIBC_KBDCODEC automatically and, for the cursor keys, the driver should be built with CONFIG_HIDKBD_ENCODED.

  • The selected font (CONFIG_LV_FONT_UNSCII_8 or CONFIG_LV_FONT_UNSCII_16) is enabled automatically by the font choice.

Reference: NuttX RTOS for PinePhone: LVGL Terminal for NSH Shell.