Shift Registers

Contributors: JordanDee
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What is a Shift Register?

A shift register is a device that allows additional inputs or outputs to be added to a microcontroller.

Shift Register 8-Bit - SN74HC595

Shift Register 8-Bit - SN74HC595


This is accomplished by converting data between parallel and serial formats. A microprocessor communicates with a shift register using serial information, and the shift register gathers or outputs information in a parallel (multi-pin) format.

Tactile button assortment

Got a lot of buttons? Consider using a shift register.

SIPO or PISO Shift Registers

Shift registers come in two basic types, either SIPO, Serial-In-Parallel-Out, or PISO, Parallel-In-Serial-Out. SparkFun carries both types. Here is a SIPO, the 74HC595, and the PISO, the 74HC165. The first type, SIPO, is useful for controlling a large number of outputs, including LEDs, while the latter type, PISO, is good for gathering a large number of inputs, like buttons.

SparkFun carries an easy to use breakout versions for both these chips as well. If you need more than 8 additional I/O lines, you can easily chain multiple shift registers together by connecting the output side of the breakout board to the right side of another board.

SparkFun Shift Register Breakout - 74HC595

SparkFun Shift Register Breakout - 74HC595