Page 58 - CITS - Electronic Mechanic - TT - 2024

ELECTRONICS MECHANIC - CITS

The shift register, which allows serial input (one bit after the other through a single data line) and produces a
parallel output is known as the Serial-In Parallel-Out shift register. The logic circuit given below shows a serial-in-
parallel-out shift register. The circuit consists of four D flip-flops which are connected. The clear (CLR) signal is
connected in addition to the clock signal to all 4 flip flops in order to RESET them. The output of the first flip-flop
is connected to the input of the next flip flop and so on. All these flip-flops are synchronous with each other since
the same clock signal is applied to each flip-flop.

The above circuit is an example of a shift right register, taking the serial data input from the left side of the flip-flop
and producing a parallel output. They are used in communication lines where demultiplexing of a data line into sev-
eral parallel lines is required because the main use of the SIPO register is to convert serial data into parallel data.
Parallel-In Serial-Out Shift Register (PISO)
The shift register, which allows parallel input (data is given separately to each flip flop and in a simultaneous man-
ner) and produces a serial output is known as a Parallel-In Serial-Out shift register. The logic circuit given below
shows a parallel-in-serial-out shift register. The circuit consists of four D flip-flops which are connected. The clock
input is directly connected to all the flip-flops but the input data is connected individually to each flip-flop through a
multiplexer at the input of every flip-flop. The output of the previous flip-flop and parallel data input are connected
to the input of the MUX and the output of MUX is connected to the next flip-flop. All these flip-flops are synchronous
with each other since the same clock signal is applied to each flip-flop.

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CITS : E & H - Electronics Mechanic - Lesson 9 - 29