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Unit 11 Latches and Flip-Flops. Ku-Yaw Chang canseco@mail.dyu.edu.tw Assistant Professor, Department of Computer Science and Information Engineering Da-Yeh University. Outline. 11.1 Introduction 11.2 Set-Reset Latch 11.3 Gated D Latch 11.4 Edge-Triggered D Flip-Flop 11.5 S-R Flip-Flop
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Unit 11Latches and Flip-Flops Ku-Yaw Chang canseco@mail.dyu.edu.tw Assistant Professor, Department of Computer Science and Information Engineering Da-Yeh University
Outline 11.1 Introduction 11.2 Set-Reset Latch 11.3 Gated D Latch 11.4 Edge-Triggered D Flip-Flop 11.5 S-R Flip-Flop 11.6 J-K Flip-Flop 11.7 T Flip-Flop 11.8 Flip-Flops with Additional Inputs 11.9 Summary Latches and Flip-flops
Flip-Flops with Additional Inputs • Additional inputs to set the flip-flops to an initial state independent of the clock • Clear input ClrN • Q = 0 • Preset input PreN • Q = 1 • Active-low • a logic 0 is required toclear or set the flip-flop Latches and Flip-flops
Flip-Flops with Additional Inputs Latches and Flip-flops
Timing Diagram for D Flip-Flop with Asynchronous Clear and Preset Latches and Flip-flops
D Flip-Flop with Clock Enable • Driven by a common clock • Hold existing data even though the data input may be changing Latches and Flip-flops
Outline 11.1 Introduction 11.2 Set-Reset Latch 11.3 Gated D Latch 11.4 Edge-Triggered D Flip-Flop 11.5 S-R Flip-Flop 11.6 J-K Flip-Flop 11.7 T Flip-Flop 11.8 Flip-Flops with Additional Inputs 11.9 Summary Latches and Flip-flops
Q+ = S + R’Q (SR=0) Q+ = GD + G’Q Q+ = D Q+ = D · CE + Q · CE’ Q+ = JQ’ + K’Q Q+ = T Q = TQ’ + T’Q (SR latch or flip-flop) (gated D latch) (D flip-flop) (D-CE flip-flop) (J-K flip-flop) (T flip-flop) Summary Latches and Flip-flops
Homework #4 • 11.5 • 11.6 • 11.7 • 11.8 • 11.9 • 11.1 • 11.2 • 11.3 • 11.4 Paper Submission, due on May 13, 2004. Late submission will not be accepted. Latches and Flip-flops