Bidirectional Shift Register: Basics, Circuit, Designing, Block Diagram, Working, and Waveforms

Summary

This video lecture explains the concept of bi-directional shift registers using D flip-flops. The professor walks through the operation, demonstrating how data shifts left or right based on the mode control (M). With M set to 1, data shifts right, and with M set to 0, data shifts left. The circuit design incorporates flip-flops connected to common clock signals and controlled by AND/OR gates. The lecture provides an in-depth look at the connections and logic that govern the shifting mechanism, helping students understand how data moves between flip-flops and how the shifting direction is controlled.

Takeaways

• 😀 The bi-directional shift register involves two terminals for data input and output, with shifting directions controlled by a mode control terminal (M).
• 😀 When mode control (M) is 1, data shifts in the right direction (shift right). When M is 0, data shifts in the left direction (shift left).
• 😀 The shifting of data is synchronized with the clock signal in the shift register, which helps control the timing of the shifts.
• 😀 The circuit uses D flip-flops, which are interconnected with AND gates, OR gates, and mode control lines to achieve bi-directional shifting.
• 😀 The mode control terminal has both an enumerated line and a direct line, which determine the shifting direction depending on their connections.
• 😀 For M = 1 (shift right), all inputs to AND gates are 0, so the output is Q3, Q2, Q1 in a sequence, corresponding to shift right operation.
• 😀 For M = 0 (shift left), the inverted logic creates a condition where Q0, Q1, and Q2 follow a sequence resulting in shift left operation.
• 😀 The mode control terminal helps determine the shifting direction, either right or left, based on its value (M = 1 for right, M = 0 for left).
• 😀 The circuit uses four flip-flops in the bi-directional shift register configuration, with clock connections and output links arranged to control data flow.
• 😀 Understanding the logic of AND and OR gates, combined with flip-flops and the mode control terminal, is key to creating a functional bi-directional shift register.

Q & A

What is a bi-directional shift register?

A bi-directional shift register is a type of shift register that allows data to shift in two directions: left and right. The direction of shifting is controlled by a mode control (M) signal.

What role does the mode control (M) play in a bi-directional shift register?

The mode control (M) signal determines the direction in which the data will shift. If M = 1, the data shifts right, and if M = 0, the data shifts left.

How is the shift register constructed in this explanation?

The shift register is constructed using four D flip-flops connected in series. A common clock signal is applied to all the flip-flops to synchronize the data shifting.

What are the components involved in controlling data flow in the circuit?

The circuit uses an OR gate and two AND gates to control the data flow, based on the mode control (M). These gates help manage how the input is fed to the flip-flops depending on the direction of the shift.

How is the clock signal involved in shifting data?

The clock signal triggers the flip-flops to latch and shift the data at each clock pulse. The shifting happens according to the direction determined by the mode control (M).

What happens when M = 1 in the bi-directional shift register?

When M = 1, the data shifts to the right. The inputs are passed through the flip-flops in the right direction, with the output progressing from Q0 to Q3.

What occurs when M = 0 in the bi-directional shift register?

When M = 0, the data shifts to the left. The data moves in the opposite direction, with the output progressing from Q3 to Q0.

How does the OR gate and AND gates help in shifting data?

The OR gate and the two AND gates help control which input (D in or Q outputs) is fed into the flip-flops based on the mode control. These gates determine if the data will shift left or right by selecting the appropriate inputs.

Why is it important to connect the mode control to both an inverted and direct line?

Connecting the mode control to both an inverted and direct line allows the circuit to manage both the right and left shift operations. The inverted line ensures proper data flow in one direction, while the direct line controls the opposite direction.

What is the significance of using four D flip-flops in the circuit?

Using four D flip-flops in the circuit enables the register to store and shift four bits of data. Each flip-flop holds one bit of data, and their connections allow the data to be shifted through the register, either to the left or the right, depending on the mode control.