Stm32f469 screen refresh rate

weefnn · July 18, 2019, 2:37pm

My F469-dico seems work OK, but some tearing effect can be found during window swich.
video:
https://pan.baidu.com/s/1mtsjNsS5xjJg-tV0612a1A

keyword: yc4v

kisvegabor · July 19, 2019, 6:29am

It might help to use true double buffering because in this case only the address of the frame buffer needs to be changed. Tearing effect might be visible in some cases but probably more rarely.

See the Two screen sized buffer configuration.

muratze · July 19, 2019, 6:56am

I tried true double buffering but as I said before I am not sure about the size of these buffers. If it is not important that the size of these buffers should be same as the screen resolution, the double buffering has not solved yet the problem. at least I couldnt solve the problem with doing this.

weefnn · July 19, 2019, 7:15am

The meaning of this parameter is a little bit confusing indeed.
It should be the size of buf_1 or buf_2 I think.

kisvegabor · July 19, 2019, 7:43am

See this as a reference:

github.com

littlevgl/lvgl/blob/master/porting/lv_port_disp_template.c#L85-L89


/* Example for 3) */
static lv_disp_buf_t disp_buf_3;
static lv_color_t buf3_1[LV_HOR_RES_MAX * LV_VER_RES_MAX];            /*A screen sized buffer*/
static lv_color_t buf3_2[LV_HOR_RES_MAX * LV_VER_RES_MAX];            /*An other screen sized buffer*/
lv_disp_buf_init(&disp_buf_3, buf3_1, buf3_2, LV_HOR_RES_MAX * LV_VER_RES_MAX);   /*Initialize the display buffer*/

Regarding size_in_px_cnt: it seems quite self-explaining to me. What is the root of the confusion? Probably it’s difficult for me to see the problem as I know what I meant by this.

muratze · July 19, 2019, 8:16am

I supposed like this before and so I tried to increase each buffer as possible as close to the 800*480 (stm32f469 tft resolution). But if I modified the buffer size as vertical and horizontal max value, ram is not enough to compile. I remember that I could give this value approximately half of the tft’s resolution.

embeddedt · July 19, 2019, 12:58pm

Shouldn’t a demo should run on that platform without needing double buffering?

kisvegabor · July 20, 2019, 3:48am

Without external RAM it really won’t work. Then triggering to TE (aka VSYNC) signal remains.