74HC165 Parallel-In Shift Register Input Expander

Read 8 buttons, switches, or sensor pins with just three Arduino pins by clocking them through a 74HC165 shift register.

Difficulty: Breadboard. Estimated build time: about 40 minutes. Estimated parts cost: about US$2.80. 5-part bill of materials with live supplier pricing. An 8-input expander built around the 74HC165, the parallel-in / serial-out cousin of the 74HC595.