Definitions Definitions Latches - Set-Reset – SR
- The D Latch
Material from section 5-3 of text
When the control input to a flip-flop changes value the state of the latch in the flip-flop will change state. When the control input to a flip-flop changes value the state of the latch in the flip-flop will change state. In a D-latch when the control input is a ‘1’, any changes on the input D will propagate to the output with the value of D at the time the control transitions from ‘1’ the final stored value. In a D flip-flop, the value on D on the rising edge (falling edge) of the control input will be the captured value.
Constructed in such a way that they are edge-triggered. Constructed in such a way that they are edge-triggered. This is in contrast to latches which are level sensitive and said to be transparent. - Edge-triggered
- Master-Slave
The Master-Slave SR Flip-flop And its operation
Can be constructed from the MS SR FF by replacing the master SR latch by a D latch. Can be constructed from the MS SR FF by replacing the master SR latch by a D latch. This arrangement is also negative edge triggered.
The SR latch model with control input C
tb model
Waveform display
The D can be constructed from the use of a D latch and an SR latch. The D can be constructed from the use of a D latch and an SR latch.
Add an inverter to the clock input
A HDL model of the D latch was written. A HDL model of the D latch was written.
Results now for the D F/F Results now for the D F/F Remember the delays
Allows direct setting of state of flip-flop. Allows direct setting of state of flip-flop. When initially powered state of flip-flop is unknown. The sets the FF to a known state.
Covered sections 5-1 and 5-2 Covered sections 5-1 and 5-2 Problems for practice Reading for next class: sections 5-4
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