The subject here is connecting the Arduino to a MM5451 LED display
driver. This is written in C to demonstrate bitwise programming and shift register operation.
Using only two input pins (clock and data) for serial date input produces 35 open drain outputs. The 35 outputs are 15mA sink.
Internal current generator eliminates need for external resistors and has continuous brightness control. Wide supply voltage up to 13.2V - inputs TTL level.
Fig. 1 shows the two connections to Arduino. MM5451 pins 11-18 (Bits 0-7) are connected to a LN516YA common-anode display (Fig. 2). further
Bit 1 is segment a. 8-LEDs are connected to pins 3-10 - all anodes go to Vcc of 5V. Note no current limiting resistors are required.
As the program runs we get a binary count on the LEDs and 0-9 on the display.
Arduino code and further information can be found at