# Modify the screen backlight driver


(modify-lcd-bl-c-file)=
## Modify the copied driver file
Here the aw9364 backlight driver is used as an example:
### Initialization
In the `aw9364_init` function, GPIO output initialization is performed on the control pin `LCD_BACKLIGHT_CONTROL_PIN`, and low is output at the same time (backlight off).

### Set backlight brightness
In the callback function `backligt_set`, the brightness percentage passed down from the upper layer is converted according to the brightness levels supported by the backlight IC, and then passed to the `sif_aw9364_set_backlight` function to set the brightness.


### Read backlight brightness
In the callback function `backligt_get`, the variable aw9364_bl is used to return the brightness, because this backlight chip does not support reading the brightness level.