# Modify the screen driver

(modify-lcd-c-file)=
## Modify the copied screen driver file

(update-lcd-param)=
### Configure screen parameters
Different screen interfaces require different parameters to be configured. The following screen interfaces each have their own corresponding parameters:

```{toctree}
:titlesonly:
DBI屏幕参数配置.md
DPI屏幕参数配置.md
DSI屏幕参数配置.md
SPI屏幕参数配置.md
JDI屏幕参数配置.md
```

### Modify the screen driver callback functions
Modify the contents of the copied screen driver to your own. The callback functions in the screen driver are described below:

_Note: optional callback functions can be registered as NULL, or their function body can be left empty_

|Callback function| Description|
|:---- | ----  |
|  [LCD_Init](lcd-cb-func-LCD-Init)|  [Required], screen driver initialization function (including reset, initialization procedure, and so on) |
|  [LCD_ReadID](lcd-cb-func-LCD-ReadID)|  [Required], screen presence detection function |
|  [LCD_DisplayOn](lcd-cb-func-LCD-DisplayOn)|  [Required], turn on the screen |
|  [LCD_DisplayOff](lcd-cb-func-LCD-DisplayOff)|  [Required], turn off the screen |
|  [LCD_SetRegion](lcd-cb-func-LCD-SetRegion)|  [Required], set the area where the screen receives data (2A, 2B area)|
|  [LCD_WritePixel](lcd-cb-func-LCD-WritePixel)|  Optional, write one pixel to the screen|
|  [LCD_WriteMultiplePixels](lcd-cb-func-LCD-WriteMultiplePixels)|  [Required], write a batch of pixels to the screen|
|  [LCD_ReadPixel](lcd-cb-func-LCD-ReadPixel)|  Optional, read one pixel of data from the screen and return the RGB value of the pixel|
|  [LCD_SetColorMode](lcd-cb-func-LCD-SetColorMode)|  Optional, switch the color format output to the screen|
|  [LCD_SetBrightness](lcd-cb-func-LCD-SetBrightness)|  Optional, set screen brightness |
|  [LCD_IdleModeOn](lcd-cb-func-LCD-IdleModeOn)|  Optional, enter standby display mode (low-power mode) |
|  [LCD_IdleModeOff](lcd-cb-func-LCD-IdleModeOff)|  Optional, exit standby display mode (low-power mode) |
|  [LCD_Rotate](lcd-cb-func-LCD-Rotate)|  Optional, rotate the screen by a certain angle |
|  [LCD_TimeoutDbg](lcd-cb-func-LCD-TimeoutDbg)|  Optional, screen self-test after bulk data transfer timeout |
|  [LCD_TimeoutReset](lcd-cb-func-LCD-TimeoutReset)|  Optional, screen reset after bulk data transfer timeout |
|  [LCD_ESDCheck](lcd-cb-func-LCD-ESDCheck)    | Optional, periodic screen ESD detection |


### Register the screen driver to the system
Register the callback functions of the screen driver IC to the system through LCD_DRIVER_EXPORT2:
```
LCD_DRIVER_EXPORT2(nv3051f1, LCD_ID, &lcdc_int_cfg,
                  &LCD_drv,2);
```

Parameter description:
- nv3051f1 - name of the screen driver IC
- LCD_ID   - the value that the screen presence detection function [LCD_ReadID](./框架介绍.md#lcd-driver-detect-method) should return when the screen is present.
- &lcdc_int_cfg - screen initialization parameters provided externally (read-only externally, used only to query screen bandwidth, color format, and other information)
- &LCD_drv - collection of callback functions for all operations of the screen driver IC
- 2 - this screen driver IC requires 2-[pixel alignment](./框架介绍.md#lcd-ic-pixel-alignment) when updating the screen area