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Learn about sequential and combinational logic circuits, memory, SR latch, D flip-flop, synchronization, and edge triggering in this interactive lab. Explore how to implement D-type positive edge-triggered flip-flops using NAND ICs.
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Logic Design LAB 8 授課老師:伍紹勳課程助教:邱麟凱、江長庭
Outlines • Sequential logic circuits • Memory and Clock • SR latch • D Flip-Flop • Lab
Sequential logic circuits • Combinational logic circuits • depends only on current inputs • Sequential logic circuits • depends on past and current inputs Memory and Clock!!
SR Latch • SR Latch (Memory) • Steady state results 0 1 0 1 R R R R 1 Q Q Q Q 0 1 Q’ Q’ Q’ Q’ S S S S 0 Q 1 Q’ 1
Clock • When to set and reset • How to synchronize devices with memory • Positive (rising) edge triggered • Negative (falling) edge triggered time
Flip Flops • Input type • SR、D、JK、T • Trigger type • Rising(positive)-edge • Falling(negative)-edge
D-type positive edge triggered FF 1 SR Latch R 2 5 Q Clock 6 Q’ 3 S 4 D
D Flip Flop Clock: 0->1 Clock = 1, D: X->X’ Clock = 0 X X->X X X’ 1 1->X’ R R R S = X, R = X’ ⟹ Set the latchas X S, R = 1 ⟹ Hold S, R will not change with D 0->1 1 0 Clock Clock 1->X Clock X 1 S S S X’ X’->1 X’ X X X->X’ D D D
Lab • Today’s target: D-type positive edge triggered Flip-Flop • IC: 7400 (NAND) x 2、LED x 1 3 How to realize three-inputs NANDs with two-inputs NANDs? How to realize three-inputs NANDs with two-inputs NANDs?