8 Digit Numerical 7 Segment SPI Display Shield for Arduino UNO

Rajkumar Sharma        
423
Project tested

8 Digit serial numerical display shield for Arduino has been designed for various applications like digital clock, stop watch, score display, temperature meter, frequency counter, digital meters etc. The circuit uses popular MAX7219 IC and two common cathode 0.5inch red seven segment displays. The MAX7219 is a compact, serial input/output common-cathode display drivers that interface Arduino UNO to 7-segment numeric LED displays of up to 8 digits. Included on-chip are a BCD code-B decoder, multiplex scan circuitry, segment and digit drivers, and an 8×8 static RAM that stores each digit. Only one external resistor R1 provided to set the segment current for all LEDs.  A convenient 3-wire serial interface connects to all Arduino UNO. Individual digits may be addressed and updated without rewriting the entire display. The MAX7219 also allows the user to select code-B decoding or no-decode for each digit. The devices include a 150µA low-power shutdown mode, analog and digital brightness control, a scan-limit register that allows the user to display from 1 to 8 digits, and a test mode that forces all LEDs on. The project works with 5V DC and SPI interface connected to Arduino Digital pins D4, D5 and D6.

Key Features

  • SUPPLY 5V DC
  • Additional CN1 provided for external micro-controller
  • Switches S1, S2, S3 for development, connected to Arduino Pin Analog A3, A4, A5
  • CN2 for analog input to Arduino Analog pin  A0
  • SPI Serial Pin connected to D4, D5, and D6 of Arduino UNO
  • Additional SPI Connector provided to use the board with other micro-controller board
  • 10MHz Serial Interface
  • Individual LED Segment Control
  • Decode/No-Decode Digit Selection
  • 150µA Low-Power Shutdown (Data Retained)
  • Digital and Analog Brightness Control
  • Display Blanked on Power-Up
  • 8 Digit Common-Cathode LED Display

Schematic

Display diagram

Parts List

Photos

 

PCB

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