LTDC worked without FreeRTOS; not with

[b1aze]

HI all i have been working with LTDC to drive an external RGB parallel display . i made it working by placing the framebuffer inside internal RAM . i got output with good update speed. but when i try to incoperate  FREERTOS with this project the output is gone . any one encountered such issues like this , any solution for this now? ;)

[Andrew Neil]

An RTOS (any RTOS) is not really something that you can just bolt-on to an existing project - it is a fundamental change to the project architecture.

You'll need to do some debugging to find why your code is not working ...

• Are basic things like UART and LEDs still working ?
• Is your display driver getting initialised properly ?
• Is your display driver getting called at all ?
• Is your display driver getting called sufficiently often ?

[Saket_Om]

Hello @b1aze 

When using FreeRTOS, it is essential to ensure that all peripheral interrupts are assigned a priority that is equal to or lower than (i.e., numerically higher than) the value specified by configMAX_SYSCALL_INTERRUPT_PRIORITY. Therefore, the priorities of the LTDC and DMA interrupts should be configured to levels that comply with this requirement to maintain system stability and proper FreeRTOS operation.

[b1aze]

Hi guys thanks for the response , right now all i know is that LTDC is being initialized , beacuse in my code 

starting address of internal RAM is given to LTDC and LTDC seems to read from the RAM , before RTOS i get full display output, but after output i get this scrambled red color on the screen , so without LTDC or clock signal i wouldn't have got anything on the display. so my assumption is that something is happeing with priority timing or my framebuffer is being scrambled somehow . whats your thoughts or ideas. 

[Andrew Neil]

Please see  How to insert source code - not as an image.

[MM..1]

H7 isnt game for kids. Show your reservation for framebuffer in linker RAM 0x24000000 etc.

[b1aze]

This is from linker script

  .framebuffer (NOLOAD) :
  {
  		. = ALIGN(32);
  		KEEP(*(.framebuffer))
  		. = ALIGN(32) ;
  		
  }>RAM

and in my code for frame buffer this 

__attribute__((section(".framebuffer"),aligned(32))) uint16_t framebuffer[LCD_WIDTH * LCD_HEIGHT];
lv_color_t lvgl_buf[LCD_WIDTH * LVGL_BUF_SIZE];
lv_disp_draw_buf_t drawbuf;
lv_disp_drv_t dispdrv;

void init_lvgl(void)
{
	lv_disp_draw_buf_init(&drawbuf, lvgl_buf,lvgl_buf, LCD_WIDTH * LVGL_BUF_SIZE);
		 /* Initialize display driver */
	lv_disp_drv_init(&dispdrv);
	dispdrv.hor_res = LCD_WIDTH;
	dispdrv.ver_res = LCD_HEIGHT;
	dispdrv.flush_cb = flush_cb;
	dispdrv.draw_buf = &drawbuf;
	dispdrv.full_refresh = 0 ;
	dispdrv.direct_mode = 0 ;
	lv_disp_drv_register(&dispdrv);
}

static void flush_cb(lv_disp_drv_t*disp, const lv_area_t *area, lv_color_t* px_map)
{
	uint32_t w = (area->x2 - area->x1 + 1);
    uint32_t h = (area->y2 - area->y1 + 1);
    uint16_t *dst = framebuffer + area->y1 * disp->hor_res + area->x1;
    uint16_t *src=(uint16_t *)px_map;
    //HAL_DMA2D_Start(&hdma2d,*(src),*(dst),w,h);
    for (uint32_t y = 0; y < h; y++) {
    	//HAL_DMA2D_Start();
        memcpy(dst, src, w * sizeof(uint16_t));
        dst += disp->hor_res;
        src += w;
    }
    lv_disp_flush_ready(disp);
}

 this is it . ask if you need anything

[MM..1]

Still not  show 0x24000000 and framebuffer ... LTDC

[b1aze]

This is my linker script and i declared my framebuffer like this in main.c file

__attribute__((section(".framebuffer"),aligned(32))) uint16_t framebuffer[LCD_WIDTH * LCD_HEIGHT];
lv_color_t lvgl_buf[LCD_WIDTH * LVGL_BUF_SIZE];

 this is it nothing else i done for frmabuffer. and inside the LTDC i gave the RAM start address

pLayerCfg.FBStartAdress = 0x24000000;

/* Entry Point */
ENTRY(Reset_Handler)

/* Highest address of the user mode stack */
_estack = ORIGIN(RAM) + LENGTH(RAM);    /* end of RAM */
/* Generate a link error if heap and stack don't fit into RAM */
_Min_Heap_Size = 0x200;      /* required amount of heap  */
_Min_Stack_Size = 0x400; /* required amount of stack */

/* Specify the memory areas */
MEMORY
{
  ITCMRAM (xrw)  : ORIGIN = 0x00000000, LENGTH = 64K
  FLASH (rx)     : ORIGIN = 0x08000000, LENGTH = 2048K
  DTCMRAM1 (xrw) : ORIGIN = 0x20000000, LENGTH = 64K
  DTCMRAM2 (xrw) : ORIGIN = 0x20010000, LENGTH = 64K
  RAM (xrw)      : ORIGIN = 0x24000000, LENGTH = 1024K
  RAM_CD (xrw)   : ORIGIN = 0x30000000, LENGTH = 128K
  RAM_SRD (xrw)  : ORIGIN = 0x38000000, LENGTH = 32K
}

/* Define output sections */
SECTIONS
{
  /* The startup code goes first into FLASH */
  .framebuffer (NOLOAD) :
  {
  		. = ALIGN(32);
  		KEEP(*(.framebuffer))
  		. = ALIGN(32) ;
  		
  }>RAM
  
  .isr_vector :
  {
    . = ALIGN(4);
    KEEP(*(.isr_vector)) /* Startup code */
    . = ALIGN(4);
  } >FLASH

  /* The program code and other data goes into FLASH */
  .text :
  {
    . = ALIGN(4);
    *(.text)           /* .text sections (code) */
    *(.text*)          /* .text* sections (code) */
    *(.glue_7)         /* glue arm to thumb code */
    *(.glue_7t)        /* glue thumb to arm code */
    *(.eh_frame)

    KEEP (*(.init))
    KEEP (*(.fini))

    . = ALIGN(4);
    _etext = .;        /* define a global symbols at end of code */
  } >FLASH