软硬件系统编程PPT (16).pdf

触发器与加法器 Flip-flop and Adder Logic circuit  Logic circuit, based on binary, is a circuit consisting various logic gates to make digital signal logical operation  Combinational logic circuit  output at any time depends only on its input, and has nothing to do with the previous state of circuit (without memory function)  Sequential logic circuit  output at any time depends on its input as well as the previous state of circuit (with memory function) 2 1. Flip-flop  Flip-flop is a logic circuit constructed by basic logic circuit and it has memory function belonging to sequential logic circuit  Power on ：  it can output a high level or a low level  when trigger signal occurs, the output state will invert  from high level to low level/from low level to high level  If the signal of flip-flop is invalid, the output state will remain the same until the new signal occurs or power off 3 Flip-flop RS Flip-flop output Logic truth table of RS flip-flop G1 S R Q Q Two S & Q 0 1 1 0 stable states 1 0 0 1 Input 1 1 X X The state remains