Random dots on screen

shadowpho · February 18, 2022, 3:10am

Description

When I run my LVGL app I see random dots on the screen (green and blue as you can see). They are 100% same every time. It appeared after I updated my LVGL version. Sadly I do not have a record of my previous LVGL version so I am a bit sad on how to fix it. It kinda looks like debug dots, as they are very regular. I tested it on multiple devices. Any idea what I can to debug?

What MCU/Processor/Board and compiler are you using?

ESP32-S2, ILI9488, FT6206, custom PCB.

What have you tried so far?

Updating to master. Different widgets?

Code to reproduce

N/A

shadowpho · February 21, 2022, 6:43am

Anyone have any thoughts? I tried to google and search on forums, but nothing came up for “random dots”

bader · March 7, 2022, 6:27pm

Are they random or always in the same place? if they are consistent, it is probably from the disp_flush function not sending the whole frame especially the last pixel. Otherwise if they are random, check the wires that goes to the LCD.

shadowpho · March 8, 2022, 4:54pm

Always in the same place.

There’s two sets of dots: one on the far right edge of the screen, spaced at certain distance, and one set a pixel to the right of where the menu bar opens.

I will look at the disp_flush, thank you! It’s just so weird and strange.

I guess I can delete all the things on the screen, then put an if statement to see if it sends green color at all?

bader · March 8, 2022, 5:12pm

I encauntered the same problem a while ago. It was the disp_flush function sends all the frame pixels except the last one, hence the white dots at the end of each frame.

I suggest you manually call the disp_flush function and send some frames to the LCD before the Lvgl library is initialized. If the dots appear, then it is definitely from this function.

shadowpho · March 11, 2022, 2:02am

Interesting.

Can you give me pointers please? Here is the code I tried, but it does not seem to display anything. Am I missing any flushing code?

    lv_area_t left_top, right_top, middle;
    lv_color_t red, green, blue;
    left_top.x1=left_top.y1=0; left_top.x2=left_top.y2=50;
    middle.x1=100; middle.y1=100; middle.x2=150; middle.y2=150;
    right_top.x1=200; right_top.y1=0; right_top.x2=250; right_top.y2=50;
    red.ch.red=31; 
    green.ch.green=63;
    blue.ch.blue=31;
    

    ili9488_flush(NULL,&left_top,&red);
    ili9488_flush(NULL,&right_top,&green);
    ili9488_flush(NULL,&middle,&blue);

    while(1);

bader · March 11, 2022, 9:50am

The disp_flush function takes an array of lv_color_t. Try something like this.

	lv_color_t buf_1[50*50];         // I think it should be global variable               
	for (int i = 0; i<50*50; i++){
		buf_1[i] = red;
	}
	disp_flush(NULL,&left_top,buf_1);

	for (int i = 0; i<50*50; i++){
		buf_1[i] = green;
	}
	disp_flush(NULL,&right_top,buf_1);

	for (int i = 0; i<50*50; i++){
		buf_1[i] = blue;
	}
	disp_flush(NULL,&middle,buf_1);

shadowpho · March 11, 2022, 6:48pm

It seems sadly I can’t easily use LVGL_ESP32 driver without initializing LVGL as well. I tried several things, but it seems that LVGL_ESP32 init actually goes and initializes a timer that checks if SPI is free for a transaction. This causes it to crash in spi_ready code.

Also not sure why it’s drawing in the same place. Should I try to use the built in screenshot function to see what it " thinks" is on the display?


#define temp_size 100
lv_color_t buf_1[temp_size*temp_size];

void guiTask(void *pvParameter)
{

    lvgl_driver_init();

    lv_area_t left_top, right_top, middle;
    lv_color_t red={0}, green={0}, blue={0};
    left_top.x1=left_top.y1=0; left_top.x2=left_top.y2=temp_size;
    middle.x1=100; middle.y1=100; middle.x2=100+temp_size; middle.y2=100+temp_size;
    right_top.x1=200; right_top.y1=0; right_top.x2=200+temp_size; right_top.y2=temp_size;
    red.ch.red=31; 
    green.ch.green=63;
    blue.ch.blue=31;
    
    for (int i = 0; i<temp_size*temp_size; i++){
		buf_1[i] = red;
	}
	disp_driver_flush(NULL,&left_top,buf_1);


    for (int i = 0; i<temp_size*temp_size; i++){
		buf_1[i] = green;
	}
	disp_driver_flush(NULL,&right_top,buf_1);


	for (int i = 0; i<temp_size*temp_size; i++){
		buf_1[i] = blue;
	}
	disp_driver_flush(NULL,&middle,buf_1);

    while(1)   vTaskDelay(1000 / portTICK_PERIOD_MS);;
}

Guru Meditation Error: Core  0 panic'ed (LoadProhibited). Exception was unhandled.

Core  0 register dump:
PC      : 0x4002bd01  PS      : 0x00060031  A0      : 0x8002c73c  A1      : 0x3ffcc9b0
0x4002bd01: spi_ready at F:\Programming\ESP32-Sensor-Software\build/../components/lvgl_esp32_drivers/lvgl_tft/disp_spi.c:316

A2      : 0x3ffde224  A3      : 0x3ffcf3cc  A4      : 0x22341313  A5      : 0x00000000
A6      : 0x3ffccc00  A7      : 0x00000050  A8      : 0x8002bd01  A9      : 0x3ffcc980
A10     : 0x00000000  A11     : 0x22341313  A12     : 0x22341313  A13     : 0x3ffd8be0
A14     : 0x00060523  A15     : 0x00000000  SAR     : 0x0000001d  EXCCAUSE: 0x0000001c
EXCVADDR: 0x00000000  LBEG    : 0x22341313  LEND    : 0x3ffd8be0  LCOUNT  : 0x4002b465
0x4002b465: _xt_user_exc at F:/Programming/esp-idf/components/freertos/port/xtensa/xtensa_vectors.S:633

Core  0 was running in ISR context:
EPC1    : 0x40083ea5  EPC2    : 0x00000000  EPC3    : 0x00000000  EPC4    : 0x00000000
0x40083ea5: panic_print_str at F:/Programming/esp-idf/components/esp_system/panic.c:126



Backtrace:0x4002bcfe:0x3ffcc9b00x4002c739:0x3ffcc9e0 0x4002c8e9:0x3ffcca10 0x4002b586:0x3ffcca40 0x40096bc3:0x3ffd8c80 0x40114cc7:0x3ffd8cb0
0x4002bcfe: spi_ready at F:\Programming\ESP32-Sensor-Software\build/../components/lvgl_esp32_drivers/lvgl_tft/disp_spi.c:308

0x4002c739: spi_post_trans at F:/Programming/esp-idf/components/driver/spi_master.c:579 (discriminator 1)

0x4002c8e9: spi_intr at F:/Programming/esp-idf/components/driver/spi_master.c:613

0x4002b586: _xt_lowint1 at F:/Programming/esp-idf/components/freertos/port/xtensa/xtensa_vectors.S:1111

0x40096bc3: esp_vApplicationIdleHook at F:/Programming/esp-idf/components/esp_system/freertos_hooks.c:50

0x40114cc7: prvIdleTask at F:/Programming/esp-idf/components/freertos/tasks.c:3974





ELF file SHA256: f66a23e3d885963d

CPU halted.

bader · March 12, 2022, 12:55am

Mmm interesting. I am sorry I am not that familiar with RTOS.

It is very strange. Try to breakpoint on each flush call and see what has been drown each time breakpoint hits or enter a delay between flushes. I suspect if you are using DMA with SPI, you are changing the content of the buffer before the current dma transfer complete.

Also, could you post your disp_driver_flush function or just use the one in the github and try it out, it may work with you?