VGA scanning timing sequence

The scanning timing of VGA can be divided into four stages: synchronization pulse a, display trailing edge b, display timing segment c, and display leading edge d.
Synchronization pulse a indicates the start of the scanning of a new row of pixels and also marks the end of the previous row's scanning.
Display timing c is the actual display area of the image. During this stage, pixels are displayed one by one, that is, the RGB values corresponding to the pixels are output in this stage. In this stage, the red, green, and blue primary color signals must all be 0.
Since the path of the electron beam's movement starts from the upper left corner of the image and moves from left to right point by point, after each row of scanning is completed, the electron beam needs to return from the rightmost position to the leftmost position to start the scanning of the next row. This movement time is the synchronization pulse a. After the end of synchronization pulse a, the signal changes from 0 to 1, bringing in an ascending edge, and enters the display signal. This display signal consists of the display trailing edge b, display timing c, and display leading edge d. Among them, only display timing c is truly capable of displaying pixels, that is, in this section, valid RGB values need to be output to ensure the display effect.