examples/lvgldemo: Select default demo

[lupyuen]

Summary

The LVGL Example App lvgldemo currently requires 1 argument: the name of the demo to show.

lvgldemo widgets

In this PR, we propose to make the argument optional if there is only one demo configured. This will enable PINE64 PinePhone to boot straight into lvgldemo and auto-start the LVGL App, without entering any nsh commands.

Modified Files

examples/lvgldemo/lvgldemo.c: If no arguments are specified and only 1 demo exists, select the demo

Impact

With this PR, lvgldemo will no longer require an argument if there is only one demo configured. So this command:

lvgldemo

Is equivalent to lvgldemo widgets if there is only one demo widgets configured.

If there is more than one demo configured, or if an argument is provided, lvgldemo will work the same way as before.

Testing

We successfully tested lvgldemo with a Single Configured Demo:

lvgldemo
  [Shows Widgets Demo]
lvgldemo widgets
  [Shows Widgets Demo]

(See the Test Log)

And we tested lvgldemo with Multiple Configured Demos:

lvgldemo
  [Shows List of Configured Demos and exits]
lvgldemo music
  [Shows Music Demo]
lvgldemo stress
  [Shows Stress Demo]

(See the Test Log)

Also we verified that PinePhone boots successfully to the lvgldemo widgets demo automatically, without entering any nsh commands.

(Demo Video)

(Another Demo)

We configured the PinePhone build as follows:

tools/configure.sh pinephone:lvgl
make menuconfig

1. RTOS Features > Tasks and Scheduling

   • Set "Application entry point" to lvgldemo_main

     (INIT_ENTRYPOINT)

   • Set "Application entry name" to lvgldemo_main

     (INIT_ENTRYNAME)

2. Application Configuration > NSH Library

   • Disable "Have architecture-specific initialization"

     (NSH_ARCHINIT)