After seeing things like the DigitGrid and the Pligboot Matrix I decided that I was going to build a 7 segment LED matrix to add to my collection of LED clocks and displays.
First off was deciding how big I wanted to go. I decided on a nice round 512 seven segment displays. I did not want to have one massive board to contain everything so I broke the display board into sixteen smaller boards.
Each board will contain a four MAX7219's driving two four character 7 segment displays for a total of 32 characters per board.
I decided that driving all sixty four MAX7219's in one massive SPI chain was probably a bad idea so they have been configured in eight rows of eight controllers each. I figured this gave a good balance between speed and not driving myself crazy with wiring.
To control all of the display board I decided to go with an Intel MAX10 FPGA as I have worked with them a lot. A Pi Pico does all of the graphics computation and feeds the data to the FPGA for mapping to the 7 segment array. Kind of an elegant solution as the software does not have to care what it is displaying but rather just needs to know the resolution.
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