Simple Input Port Expender Circuit

We can use PISO IC for increase input port of microcontroller
They can expender output port from three port to eight port

74LS165 are 8-Bit Parallel In/Serial Output Shift Registers
which shifts data in the direction of QA toward QH when clocked.
Parallel-in access is made available by eight individual direct data
inputs, which are enabled by a low level at the shift/load
input. These registers also feature gated clock inputs and
complementary outputs from the eighth bit.

C code for 74165