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doc(disp): describe "Decoupling the display refresh timer"

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Introduced in 85cc84ad94
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Gabor Kiss-Vamosi
2022-02-16 09:27:41 +01:00
parent 7cf5709b06
commit e4824f5f6b
1 changed files with 22 additions and 1 deletions
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docs/porting/display.md
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@@ -191,7 +191,9 @@ void my_clean_dcache_cb(lv_disp_drv_t * disp_drv, uint32)
} }
``` ```
## Rotation ## Other options
### Rotation
LVGL supports rotation of the display in 90 degree increments. You can select whether you'd like software rotation or hardware rotation. LVGL supports rotation of the display in 90 degree increments. You can select whether you'd like software rotation or hardware rotation.
@@ -207,6 +209,25 @@ Display rotation can also be changed at runtime using the `lv_disp_set_rotation(
Support for software rotation is a new feature, so there may be some glitches/bugs depending on your configuration. If you encounter a problem please open an issue on [GitHub](https://github.com/lvgl/lvgl/issues). Support for software rotation is a new feature, so there may be some glitches/bugs depending on your configuration. If you encounter a problem please open an issue on [GitHub](https://github.com/lvgl/lvgl/issues).
### Decoupling the display refresh timer
Normally the dirty (a.k.a invalid) areas are checked and redrawn in every `LV_DISP_DEF_REFR_PERIOD` milliseconds (set in `lv_conf.h`).
However, in some cases you might need more control on when the display refreshing happen, for example to synchronize rendering with VSYNC or the TE signal.
You can do this in the following way:
```c
/*Delete the original display refresh timer*/
lv_timer_del(disp->refr_timer);
disp->refr_timer = NULL;
/*Call this anywhere you want to refresh the dirty areas*/
_lv_disp_refr_timer(NULL);
```
If you have multiple displays call `lv_disp_set_deafult(disp1);` to select the display to refresh before `_lv_disp_refr_timer(NULL);`.
Note that `lv_timer_handler()` and `_lv_disp_refr_timer()` can not run at the same time.
## Further reading ## Further reading
- [lv_port_disp_template.c](https://github.com/lvgl/lvgl/blob/master/examples/porting/lv_port_disp_template.c) for a template for your own driver. - [lv_port_disp_template.c](https://github.com/lvgl/lvgl/blob/master/examples/porting/lv_port_disp_template.c) for a template for your own driver.