EngorioMatrixFlow MAX7219 Scrolling LED Display
About this project
MatrixFlow chains four 8×8 LED matrix modules controlled by MAX7219 display driver ICs into a 32×8 pixel scrolling banner — the same hardware used in train station departure boards, stock ticker displays, and factory alert panels. The four MAX7219s share a single SPI bus (three wires: MOSI, CLK, CS) in a daisy-chain: each IC passes data to the next when the CS pin pulses, like a 192-bit shift register. To address a specific MAX7219, data must be clocked through all preceding ICs simultaneously with no-op (0x00,0x00) padding. A 5×7 pixel character font is encoded as 59 arrays of five column bytes stored in program flash (PROGMEM) to avoid consuming the ATmega328P's limited 2KB SRAM. A scroll buffer holds the entire message as 8-bit column bitmaps; at each scroll tick (configurable 30–500ms), the display window shifts one column to the right through the buffer. Serial commands change the message (MSG), speed (SPEED), brightness (BRIGHT), and display mode (SCROLL/BLINK/COUNT). A countdown mode displays a two-digit number that decrements once per second in large 5×7 numerals. This project teaches five distinct CSE concepts: SPI protocol framing and daisy-chain addressing, the MAX7219 register map (DECODE_MODE, INTENSITY, SCAN_LIMIT, SHUTDOWN), PROGMEM font encoding and pgm_read_byte() access, rolling buffer scrolling algorithm, and Arduino SPI.h hardware accelerated transfer versus bit-bang shiftOut(). Build time: 3 hours.
What you get
- Complete, commented source code
- Full components list with quantities
- Pin-by-pin wiring guide and connection table
- Step-by-step upload and testing guide
- Project report (.docx, IEEE style)
- Presentation slides (.pptx)
