View source for Minecraft:Redstone mechanics/Redstone signal (technical)

{{Exclusive|Java|customtext=The contents of this page might apply exclusively to {{JE}}. <br>
It is not known whether the behaviors described in this page apply to {{BE}} as well, due to Bedrock's source code not being as easy to decompile as Java's.}}
{{main|Redstone mechanics#Redstone signal}}
A ''redstone signal'' (also known as ''redstone power'') is a property common to all blocks in the game. Its value, known as ''signal strength'', can range between 0 and 15 (inclusive).

==Behavior==
[[File:Repeater power.png|thumb|The signal strength of a powered [[repeater]] is 15 for the direction it's facing and 0 for all other directions.]]
Redstone signals are directional, meaning that a redstone power source can have different signal strengths for each direction—certain redstone components emit a signal with a strength greater than 0 only for ''some'' directions. For the sake of simplicity, signal strength 0 is often referred to as the lack of a redstone signal.

The actual direction of a signal is inverted compared to the one that can be observed in-game: for example, the signal emitted by a [[Minecraft:redstone torch]] that's powering a [[Minecraft:piston]] above itself has the {{code|DOWN}} direction.<ref group="note">This is just a technicality, the rest of the wiki uses the intuitive (not based on the game's [[Minecraft:code]]) directions.</ref> In the aforementioned example, the piston extends only if the direction it's facing doesn't match the direction of the signal.

There are two types of redstone signal: {{Tooltip|'''signal'''|net.minecraft.world.level.block.state.BlockBehaviour#getSignal}} (conceptually similar to the community terms ''weak power'' or ''activation'') and {{Tooltip|'''direct signal'''|net.minecraft.world.level.block.state.BlockBehaviour#getDirectSignal}} (conceptually similar to the community terms ''strong power'' or ''block powering''). Most blocks use the default signal strength value of 0 for both ''signal'' and ''direct signal'', however redstone power sources override this value, usually depending on the block's current [[Minecraft:blockstate|state]].

===Signal===
{{Partially conjecture|section=3}}
[[File:Redstone block power.png|thumb|[[Redstone block]]s emit ''signal'' with a strength of 15 in all directions. ''Direct signal'' is emitted with a strength of 0 for all directions.]]
''Signal'' is a type of redstone signal that powers the block adjacent to the power source for the specified direction.

===Direct signal===
{{Partially conjecture|section=3}}
[[File:Comparator power.png|thumb|A [[redstone comparator]] reading a full [[Minecraft:composter]] emits both ''signal'' and ''direct signal'' with a strength of 8 in the direction it's facing (all other directions have signal strength 0).]]
''Direct signal'' is a type of redstone signal that does ''not'' power the adjacent block for the specified direction, but instead powers the direct neighbors of that adjacent block, if it is [[Minecraft:conductive]]. The strength of ''direct signal'' is either always 0 (for blocks that lack ''direct signal'') or matches the strength of the block's ''signal''.
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==Misconceptions==
[[File:Repeater vanilla.png|thumb| A [[vanilla]] redstone repeater powering a [[Minecraft:redstone lamp]] and a piston. The redstone lamp is receiving ''signal'' and the piston is receiving ''direct signal''.]]
[[File:Repeater modded.png|thumb| A redstone repeater after modifying the game's code to make it emit ''signal'' with a strength of 0 while keeping ''direct signal'' at a strength of 15. Notice how the lamp is not turning on.]]
Over the years, the redstone community has come up with various theoretical explanations that tackle certain redstone quirks. Unfortunately, these explanations do not always match what's actually happening in the game's [[Minecraft:code]], therefore leading to some misconceptions.
===Redstone dust power===
Some players believe the reason why all other power sources can power [[Minecraft:redstone dust]] through conductive blocks but redstone dust itself cannot is due to the existence of two types of power: ''soft power'' and ''hard power''. According to this logic, redstone dust emits soft power and every other power source emits hard power.

<!--Explanation is not comprehensible enough-->In reality, the cause of this phenomenon is that the strength of the emitted ''signal'' and ''direct signal'' of all redstone wires in the game is temporarily changed to 0 whenever any redstone wire is checking for power. This is controlled by the {{Tooltip|{{code|shouldSignal}}|net.minecraft.world.level.block.RedStoneWireBlock#shouldSignal}}
boolean flag, which is then set back to {{code|true}} after the signal check.

Redstone dust can still be powered by other connected redstone wires even while the {{code|shouldSignal}} flag is set to {{code|false}} because it checks their {{code|POWER}} [[Minecraft:blockstate]].

===Emitted signals===
A redstone power source that emits a ''direct signal'' with a strength greater than 0 for a given direction '''always''' also emits a ''signal'' with the same strength<ref group="note">Keep in mind that the strength of ''direct signal'' is based on the strength of ''signal'', not the other way around.</ref> for that same direction—otherwise, the power source wouldn't be able to power the block directly adjacent to it, but would instead only power the neighbors of said block.

This is different compared to the community's interpretation of redstone signals, according to which a redstone power source only emits one signal type per direction.
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==Unusual signal strengths==
{{Expand section}}
{{Uses bug|section=2}}
[[File:Redstone comparator ss165.png|thumb|At the top: a comparator reading a hopper with signal strength 165. Notice how the redstone dust is still on even after subtracting a total signal strength of 15+15+15 = 45 from the comparators. <br>
At the bottom: a comparator reading a hopper with signal strength 15.]]
Signal strength can technically be any non-fractional number between -2147483648 and 2147483647 (inclusive), due to it being a signed 32-bit {{w|integer}}. All redstone components are however limited to the 0-15 range, excluding [[Minecraft:comparator]]s. A comparator that reads the items from a [[Minecraft:container]] can output a signal outside of the usual range if the container in question has negative [[Minecraft:item]] stacks (signal strength below 0) or stacked unstackable items (signal strength above 15) inside of it. Such items can be obtained with the use of bugs, which might or might not have been patched depending on the game's version.{{More info}}

When a comparator that has an unusual signal strength interacts with any powerable component excluding other comparators, that component will reset it to either 0 (if it's less than 0) or 15 (if it's greater than 15). For example, using a comparator with signal strength 20 to power a piece of redstone dust causes the latter to emit a signal with a strength of 15.
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== References ==
<references group="note" />

== Navigation ==
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