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Codiode/Problems/Sequential Logic

4-Bit Bidirectional Shift Register: Basic Construction

EasyLogic CircuitBuild

High-speed serial interfaces and arithmetic units rely on data paths that can shift bits in either direction. The bidirectional shift register allows a single hardware block to handle both transmit and receive serialization, or perform fast multiply-by-two and divide-by-two operations.

Construct a 4-bit bidirectional shift register. A direction control signal DIR selects the shift behavior. Provide a 2:1 multiplexer at the data input of each flip-flop to route the correct neighbor or serial input. All flip-flops must be clocked by the clk signal.

| DIR | D0 | D1 | D2 | D3 | |-------|------|------|------|------| | 0 | SER_R | Q0 | Q1 | Q2 | | 1 | Q1 | Q2 | Q3 | SER_L|

Constraints

  • Use exactly four D flip-flops and four 2:1 multiplexers.
  • Connect the clk input to the clock pin of every flip-flop.
  • Do not use pre-built shift register macros.

Topics

MultiplexersSequential LogicShift Registers

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