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Flip-Flops
A flip-flop is a type of latch that is connected to a clock signal and which executes in time with the clock's pulse. (Sometimes "latch" and "flip-flop" are used interchangeably but technically a latch is flip-flop without a clock connection.)
JK Flip-Flop
The JK Flip-Flop (the letters are meaningless) is basically an SR latch in functionality. It has a "set" input (J) and a "reset" input (K) and Q and inverted-Q outputs.
Where it differs from the SR is that it the SR will change state just if the voltage is high (this, afterall, is all that a bit is) whereas for the JK to set it must receive a clock pulse and it will only set on the pulse.
In addition the JK Flip-Flop has a toggle function. When this is executed, whatever Q currently is will be flipped to its opposite value: 1 \rightarrow 0, 0 \rightarrow 1. The toggle executes when both J and K are set to high.
The possible state changes for the JK Flip-Flop are detailed below:
| J | K | Clock | Q state | Operation |
|---|---|---|---|---|
| 0 | 0 | Pulse | Maintain previous value | Hold |
| 0 | 1 | Pulse | 0 | Reset |
| 1 | 0 | Pulse | 1 | Set |
| 1 | 1 | Pulse | Inverse of previous value | Toggle |
A JK Flip-Flop can execute on either the positive or negative pulse. Below are the diagrams fora rising and falling pulse respectively:
// TODO diagram of JK Flipflop