MAX7219X4

Features

• (4) MAX7219 8 digits, 7 Segment display modules
• 32 digits
  • 4 rows
  • 8 digits per row
• Can display decimal, hex values, some text values
• Each display has 8 of 7 segment LED displays
• "Blue" card
  • ebay search
  • Not compatible with red modules
• 3.3V interface operation
  • 3.3V to 5V Level shifter
• Requires both 3.3V and 5V power supplies
• 8 pin connector
• 95x95mm ODAS form factor
• (4) 6-32 mounting holes

J1 Connector

• 3.3V level
• 1x8 right angle header mounted on rear of card

1. GND
2. GND
3. DOUT
4. CLK
5. CS
6. DIN
7. 3.3V
8. 5V

Programming

Arduino Drivers

• MAX7219X4 Arduino GitHub repository
  • Uses Arduino LedControl library
    • Library only writes to (1) 8-digit display
  • Pins
    • Arduino UNO pin 12 is connected to the DataIn
    • Arduino UNO pin 11 is connected to the CLK
    • Arduino UNO pin 10 is connected to CS
• LEDMatrixDriver - Alt driver
  • Can drive more than 8 segments (limited only by memory)
  • Writing to the display is controlled by software
  • Much faster because it uses hardware SPI with soft SS
  • Recommended pins for Arduino Uno:
    • DIN is connected to 11
    • CLK is connected to 13
    • CS is connected to 9
• MAX72XX - Alt driver
  • One or more 7-segment displays driven by a MAX7219 or MAX7221 IC

Test

Test Modules

• Arduino Sensor Shield

SenShld	Desc	MAX J1	Color
VCC	VCC	1	RED
GND	GND	2	BLK
D12	DATAIN	3	WHT
D10	CS	4	BRN
D11	CLK	5	YEL

"Red" Modules

• Incompatible pinouts
  • Flipped from blue modules

Mechanicals

Assembly Sheet

• MAX7219X4 Assembly Sheet