Microcontrollers often have a very limited number of GPIO pins. Serial-in parallel-out shift registers can be used to output to a large number devices while only utilizing a few GPIO pins from the controller.

See more about this use case in the Logic Minute video Increase the Number of Outputs on a Microcontroller.

• Serial input data (BR_in) must be faster than the desired output data rate (BR_out) based on the number of output bits (N) by this equation: BR_in (Mbps) = BR_out (Mbps) × N
• The clock input controls the rate at which data is loaded into the shift register, F_clk (MHz) = BR_in (Mbps)
• For more outputs, shift registers can be daisy-chained together
• [FAQ] What is the default output of a latched device? (Flip-Flop, latch, register)
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