LVGL does not display anything

[33691A-Gold_Dusk]

Hello All,

When we write our LVGL display code, we put it into the initialize() function with a delay included. When we download to the cortex, nothing shows up. Below is a snippet of my code (keep in mind that I have already declared my button variable, I just did not include those for the sake of space).

pros::delay(50);

lv_style_copy(&RedREL, &lv_style_plain);
RedREL.body.main_color = LV_COLOR_MAKE(150, 0, 0);
RedREL.body.grad_color = LV_COLOR_MAKE(150, 0, 0);
RedREL.body.radius = 0;
RedREL.text.color = LV_COLOR_MAKE(255, 255, 255);


lv_style_copy(&RedPR, &lv_style_plain);
RedPR.body.main_color = LV_COLOR_MAKE(255, 0, 0);
RedPR.body.grad_color = LV_COLOR_MAKE(255, 0, 0);
RedPR.body.radius = 0;
RedPR.text.color = LV_COLOR_MAKE(255, 255, 255);

lv_style_copy(&BlueREL, &lv_style_plain);
BlueREL.body.main_color = LV_COLOR_MAKE(0,0,150);
BlueREL.body.grad_color = LV_COLOR_MAKE(0,0,150);
BlueREL.body.radius = 0;
BlueREL.text.color = LV_COLOR_MAKE(255,255,255);

lv_style_copy(&BluePR, &lv_style_plain);
BluePR.body.main_color = LV_COLOR_MAKE(0,0,255);
BluePR.body.grad_color = LV_COLOR_MAKE(0,0,255);
BluePR.body.radius = 0;
BluePR.text.color = LV_COLOR_MAKE(255,255,255);

myButton = lv_btn_create(lv_scr_act(), NULL); //create button, lv_scr_act() is deafult screen object
lv_obj_set_free_num(myButton, 0); //set button is to 0
lv_btn_set_action(myButton, LV_BTN_ACTION_CLICK, btn_click_action); //set function to be called on button click
lv_btn_set_style(myButton, LV_BTN_STYLE_REL, &RedREL); //set the relesed style
lv_btn_set_style(myButton, LV_BTN_STYLE_PR, &RedPR); //set the pressed style
lv_obj_set_size(myButton, 200, 50); //set the button size
lv_obj_align(myButton, NULL, LV_ALIGN_IN_TOP_LEFT, 0, 0); //set the position to top mid	

myLabel = lv_label_create(lv_scr_act(), NULL); //create label and puts it on the screen
lv_label_set_text(myLabel, "Button has not been clicked yet"); //sets label text
lv_obj_align(myLabel, NULL, LV_ALIGN_IN_BOTTOM_MID, 0, 0); //set the position to center

[Codec]

First why do you need the 50millisecond delay, it shouldn’t cause any problems, but what purpose does it serve?

Did you declare all the style variables and the function btn_click_action? Also check that your code loop has delays, since lvgl runs in a separate thread. Other then that I can’t think of anything that would go wrong. Are there any errors?

Also seeing your entire code would help (upload as a zip file).

[jpearman]

delay may be related to this issue.

LVGL Issues

It’s some sort of PROS lvgl initialization issue, adding small delay fixes it. void initialize() { // pros::lcd::initialize(); // pros::lcd::set_text(1, "Hello PROS User!"); // // pros::lcd::register_btn1_cb(on_center_button); pros::delay(100); gui(); } exactly why the inverted screen changes the timing I’m not sure. I pulled the same code into my VEXcode LVGL project and it’s runs without issue in either case, no delay needed.

try with the delay as 100mS.