Bus fault crash when updating label text on Sharp Memory Display with nRF52840

How-to
1

What do you want to achieve?

I am trying to display and update a label’s text on the nRF52840-DK and Sharp LS013B7DH05 Memory Display (144x168 px). I am using the nrf connect SDK (v3.0.1) which is based on zephyr v4.0.99 which includes lvgl v9.3.

I am able to show a label’s text on the display, but get a runtime error (bus fault) after updating the label’s text.

Currently, I can create the label and show the text on the screen with no issue, but when I update the label’s text (with lv_label_set_text()), the application will crash either on the next call to lv_refr_now(NULL) or an upcoming lv_timer_handler() call, before the display updates to the new text.

What have you tried so far?

  • I’ve tried giving more heap/stack memory to the application/lvgl (in prj.conf).
  • I’ve tried manually initializing lvgl and my display instead of using the NCS/zephyr default initialization
  • I’ve ran the application in debug mode and discovered the following, which I believe to be the cause (though I don’t know why this behavior is happening):
    • After the text is updated and the display is refreshing, the invalidated area of the display shows width=65534, height=-1 (suggesting integer overflow). This then causes a crash when lvgl attempts to draw to the display.

Code to reproduce

lv_obj_t *test_label = lv_label_create(lv_screen_active());
lv_obj_align(test_label, LV_ALIGN_TOP_LEFT, 0, 0);
lv_label_set_text(test_label, "initial");
lv_timer_handler(); // the display correctly shows the label text

// ... some time later (or immediately after the above) ...
lv_label_set_text(test_label, "changed");
lv_refr_now(NULL); // Runtime error here!

for reference, here is the part of my devicetree overlay to define the sharp display:

/ {
	chosen {
		zephyr,display = &ls0xx_ls013b7dh05;
	};
};
...
&spi1 {
	compatible = "nordic,nrf-spi";
	status = "okay";
	pinctrl-0 = <&spi1_default>;
	pinctrl-1 = <&spi1_sleep>;
	pinctrl-names = "default", "sleep";
	cs-gpios = <&gpio0 30 GPIO_ACTIVE_HIGH>;

    ls0xx_ls013b7dh05: ls0xx@0 {
        compatible = "sharp,ls0xx";
        reg = <0>;
        spi-max-frequency = <1100000>;
        label = "display";
		width = <144>;
		height = <168>;
		extcomin-gpios = <&gpio1 10 0>;
		extcomin-frequency = <60>;
		disp-en-gpios = <&gpio1 11 0>;
    };
};

Environment

  • MCU/MPU/Board: nRF52840-DK
  • Display: Sharp Memory Display 144x168 (LS013B7DH05)
  • LVGL version: v9.3
  • NRF Connect SDK version: v3.0.1
  • Zephyr OS version: v4.0.99

Could anyone please help me troubleshoot this? I want to get LVGL working with the nRF52840 and sharp memory display, but I haven’t been able to figure this out and it’s making me pull out my hair.

Thanks!