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.
8 Digit Numerical 7 Segment SPI Display Shield for Arduino UNO – [Link]