74HC595 (Shift register)

Pinout

Summary

The 74HC595 is an 8-bit serial-in, parallel-out shift register with 3-state outputs. It allows you to expand the number of digital outputs by serially shifting data into the register and then outputting it in parallel. This makes it useful for driving LED displays, controlling multiple outputs with fewer pins, and other applications where you need to expand the number of outputs available from a microcontroller.

Control logic

The 74HC595 shift register uses control logic to manage data shifting and output.
It has three main controlpins:

• DS (Data): Inputs the serial data to be shifted into the register
• SH_CP (Shift Clock): This pin reads data from the DS (Data) pin on each rising edge shifting it into the shift register
• ST_CP (Storage Clock): When this pin receives a rising edge signal, it transfers the data from the shift register to the storage register, updating the output
• OE (Output Enable): This active-low pin controls whether the outputs are enabled or in a high-impedance state. When low, the outputs reflect the data stored in the storage register.