LED Matrix digital logic using Logisim

Project overview

Display arbitrary characters on a set of 8x8 square LED matrix.

In this case, four LED matrix to display "XCJ!"

Hardware

• LED Matrix: http://www.seeedstudio.com/depot/20mm-88-square-matrix-led-red-p-36.html
  • Cheap and inexpensive
  • To turn off a LED, put LOW (normally HIGH) on column/sink and HIGH (normally LOW) on row/drive
• Parallel EEPROM
  • AT28BV64B PDIP
• Digital logic (FPGA or 7400)

Simulation with Logisim

The Logisim circuit design is available on github

• Figured out 8-bit hexadecimal values for every row (using a spreadsheet)
• Created a logic block simulating a LED matrix
• Created necessary logic to refresh the same row of every LED matrix from the values stored in memory

TODO

• Convert to 7400 series logic or VHDL schematics
• Program parallel EEPROM with memory value
• Implement in hardware and test

Future

• Expand the LED matrix
• Create character lookup table in memory