Prefect for Arduino projects, LED Light Cubes, Scrolling Signs, Robotics, The Atmel AVR Microcontroller Projects, and more. The 74HC595 devices contain an 8 bit serial in, parallel out shift register that feeds an 8 bit D type storage register. The storage register has parallel 3 state outputs. Separate clocks are provided for both the shift and storage register. The shift register has a direct overriding clear (SRCLR) input, serial (SER) input, and serial outputs for cascading. When the output enable (OE) input is high, the outputs are in the high impedance state. Both the shift register clock (SRCLK) and storage register clock (RCLK) are positive edge triggered. If both clocks are connected together, the shift register always is one clock pulse ahead of the storage register.