This project is an FPGA-based screen painter similar to an Etch-A-Sketch with control over the position and color of the digital brush used. It additionally has an opening screen that displays the Mona Lisa upon first boot, and will automatically start drawing the words “Red Rum” on the screen after a period of inactivity. The key components include a cursor tracker, a frame buffer to store all pixel states, a frame updater to update the pixel states according to inputs, a ghost writer (“Red Rum”), and multiple modules providing input conditioning and VGA control. The cursor tracker stores the X and Y coordinates of the cursor position, which updates at the end of each VGA frame according to the buttons pressed (up, down, right, or left). The frame buffer is a single port RAM unit that stores the color and position of each pixel for the display. The frame updater contains a finite state machine and datapath to execute sequential pixel updates in the frame buffer according to the new cursor coordinates (ie. update the new pixels painted by the brush), or clear the screen if the clear switch is enabled. The ghost writer is an entity that can be enabled or disabled, displaying an ominous image on the VGA display after 30 seconds of inactivity. To implement this design, each submodule was individually validated using testbenches and then wired with the rest of the system and tested with the VGA module to visually confirm functionality.
