× Home MCQ Videos Basic Electrical Circuit Theories Electrical Laws Materials Batteries Illumination Generation Transmission Distribution Switchgear Protection Measurement Control System Utilities Safety Transformer Motor Generator Electrical Drives Electronics Devices Power Electronics Digital Electronics

Bidirectional Shift Register

Bidirectional shift registers are the storage devices which are capable of shifting the data either right or left depending on the mode selected. Figure 1 shows an n-bit bidirectional shift register with serial data loading and retrieval capacity. Initially all the flip-flops in the register are reset by driving their clear pins high. Next R/LÌ… control line is made either low or high in order to opt for either left-shift or right-shift of the data bits, respectively.

bidirectional shift registersNow if R/L̅ = 1, then A1 gates of all the combinational circuits get activated while the A2 gates will get disabled at the same time. Due to this, the outputs of each flip-flop appear at the inputs of the very-next flip-flop via OR gate output (except for the last flip-flop FFn).

You may also be interested on
Bidirectional Shift Register

For example, Q1 appears at D2 via the output of OR gate 1 (O1), Q2 appears at D3 via the output of OR gate 2 (O2), … and Qn-1 appears at Dn via the output of OR gate 1 (On) (red lines). At this instant if the positive edge of the clock pulse appears, then the outputs of the respective flip-flops reflect their inputs. Thus Q1 = D1, Q2 = Q1,… and Qn = Qn-1. This is nothing but right-shift of the data by a single bit within the register. Following on the same grounds, one can note that for every rising edge of the clock, the data within the register shifts right by a single bit as long as R/L̅ remains high.

On the other hand, if R/L̅ goes low, then A2 gates of the combinational circuits get enabled while A1 gates get deactivated. This causes the outputs of each flip-flop to appear at the input pins of the very-previous flip-flop through their OR gate outputs (except the first flip-flop, FF1). For example, Qn appears at Dn-1 through the output of OR gate n-1 (On-1), … Q3 appears at D2 via the output of OR gate 2 (O2), and Q2 appears at D1 via the output of OR gate 1 (O1). These input bits are latched onto their respective output pins as soon as the leading edge of the clock pulse appears and thus Qn-1 = Qn, …Q2 = Q3 and Q1 = Q2 (green lines). This means that for every clock tick, the data within the register moves left by one bit, provided R/L̅ line is zero.

The working of such bidirectional register can be summarized as in Table I and can be further explained by the output wave forms shown by Figure 2. data movement in bidirectional shift register output waveform of n-bit bidirectional shift register


Comments


New Articles
ECG Lead System ConfigurationBiological AmplifiersApplications of Resistive Transducers in Biomedical InstrumentationChopper AmplifierApplication of Transducers in Biomedical Instrumentation
Related Articles
Shift RegistersApplications of Shift RegistersUniversal Shift RegistersBidirectional Shift RegisterDynamic Shift RegisterBuffer RegisterData Transfer in Shift RegistersSISO Shift RegisterSIPO Shift RegisterPISO Shift RegisterPIPO Shift Register
More Related Articles
NumberDigital ElectronicsArithmeticLogic GateLogic FamiliesCominational CircuitSquentional CircuitLogical OperationDigital CountersDigital EncodersDigital DecoderMemoryAdderBinary Subtractor