Article: Inside a Smartphone Accelerometer: PinePhone with NuttX RTOS

[lupyuen]

That's awesome @WhiteHexagon ! And thank you so much for bearing with me :-)

(1) The Colour Bars is actually a Test Pattern that's rendered by the Display Driver in C, not in LVGL. (Source Code) (Explained here)

(2) I realise you don't have a Serial Debug Cable, so let's configure NuttX to start the LVGL Demo automatically (as explained here):

Code:

make menuconfig

In “RTOS Features > Tasks and Scheduling":
Set “Application Entry Point” to lvgldemo_main
Set “Application Entry Name” to lvgldemo_main

In “Application Configuration > NSH Library”:
Disable “Have Architecture-Specific Initialization”

(3) NuttX should now boot to the LVGL Demo App automatically (Like this)

(4) The source code for the LVGL Demo is at 
apps/graphics/lvgl/lvgl/demos/widgets/lv_demo_widgets.c
(Repo is here)

(5) To build our own LVGL Demo, edit lv_demo_widgets.c, look for the function lv_demo_widgets, and change the code inside to:

Code:

// Create a Button, set the Width and Height
void lv_demo_widgets(void) {
  lv_obj_t *btn = lv_btn_create(lv_scr_act());
  lv_obj_set_height(btn, LV_SIZE_CONTENT);
  lv_obj_set_width(btn, 120);
}

(Explained here)

(6) Yeah the LVGL code looks quite messy in C. In the next article, I'll use Zig to build a Feature Phone UI for NuttX on PinePhone. So stay tuned! :-)

UPDATE: I just remembered that I created a simple Zig LVGL App for PinePhone: pinephone-lvgl-zig

UPDATE: To fix the Arm64 / Zig toolchain on macOS, we could run a Linux Container like Rancher Desktop