Can a redstone latch in Java Edition be supplemented with a toggle function?

Question

SR latches and T-flip-flops are trivial circuitry in Minecraft redstone, but it appears that there is little to be found for a circuit that combines both, allowing for both SR and T functionality.

I envision an SR-T latch to have set, reset, and toggle inputs respectively, but all connected to the same memory cell. This means that the output can be controlled by setting it, resetting it, and toggling it all at once. Just like an SR latch, pressing S or R when the cell is already in that state should do nothing.

All of my circuitry so far has been "unclean" implementations, either a bodged wiring to add a toggle to an SR latch, or bodged wiring to add SR inputs to a T-flip-flop. What is the best way to go about making such a latch?

See also: Same question for Bedrock Edition (originally one question; separated upon request from others)

Answer 1

Maybe there's a compact way to do exactly what you want in one circuit element, but you can also just use a regular RS-NOR latch and then a circuit element that inverts signals on request.
I tried out a bunch of complex ideas around this, until I realised that this comes down to a simple logic gate, with this logic table:

┌───┬───┬───┐
│IN1│IN2│OUT│
├───┼───┼───┤
│ 0 │ 0 │ 0 │
│ 0 │ 1 │ 1 │
│ 1 │ 0 │ 1 │
│ 1 │ 1 │ 0 │
└───┴───┴───┘

Therefore, what you want is an XOR gate. The Minecraft wiki has tutorials for those: https://minecraft.wiki/w/Mechanics/Redstone/Logic_circuit#XOR_gate (archive)

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Just so this is a complete answer (and not considered a link-only answer), here's a screenshot of one of the alternative designs. Of course you'll realistically want to compare the different designs on the wiki and pick one that works best for your situation.

Answer 2

What you're looking for is still going to be based primarily around an RS latch, with a couple of AND gates to make the toggle line work properly. For this, the circuit diagram looks like this:

Breaking it down, you have an RS latch hooked up as normal. From there, you need the output and an inverted output to control two AND gates that control which input the Toggle is meant to control. That is, if the RS state is on, your toggle should control the off side of the RS latch.

I'm sure this could be done more cleanly, but the circuit I came up with is this:

Note that in the above there are sticky pistons underneath the gold blocks which act as AND gates, and a redstone repeater underneath the diamond block to keep the signal from the repeater on the Reset line from being directly connected to the Output line. Here's a closer look at that portion of the circuit:

Answer 3

I have managed to create a compact design for this so-called “SRT latch:”

This circuit uses a T-flip-flop as its base. The T-flip-flop's output is used to activate pistons that complete a circuit from the corresponding S/R input to the toggle input. This effectively treats the S/R buttons as “conditional toggles.”

This circuit is compact, simple, and uses its space effectively with a symmetrical layout. At its bare minimum, the footprint of this circuit is 5×3×2, excluding the space taken by the inputs and outputs.

Upon further thought, it turns out that this circuit is, in essence, a JK flip flop, the only difference being that the toggle function is controlled by a separate input, rather than with both inputs being on at once. This could theoretically render this design as one of the most compact JK flip flop designs in Minecraft.

This circuit is likely to work on MCBE, but has not yet been tested. I will transcribe this answer to the other question if I can confirm its functionality.