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  1. Minecraft: Java Edition
  2. MC-54711

Quick pulses get lost in some repeater/comparator setups

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    • Icon: Bug Bug
    • Resolution: Unresolved
    • None
    • Minecraft 14w17a, Minecraft 14w18b, Minecraft 14w28b, Minecraft 1.8-pre2, Minecraft 1.8-pre3, Minecraft 1.8, Minecraft 1.8.1-pre3, Minecraft 1.8.1-pre4, Minecraft 1.8.1, Minecraft 1.8.2-pre4, Minecraft 1.8.7, Minecraft 15w31c, Minecraft 15w44a, Minecraft 15w45a, Minecraft 15w46a, Minecraft 15w47c, Minecraft 15w49a, Minecraft 1.8.9, Minecraft 15w50a, Minecraft 15w51b, Minecraft 16w02a, Minecraft 16w03a, Minecraft 16w04a, Minecraft 16w05b, Minecraft 16w06a, Minecraft 16w07a, Minecraft 16w07b, Minecraft 1.9 Pre-Release 1, Minecraft 1.9 Pre-Release 3, Minecraft 1.9 Pre-Release 4, Minecraft 1.9, Minecraft 1.9.1 Pre-Release 3, Minecraft 1.9.1, Minecraft 1.9.2, Minecraft 1.9.4, Minecraft 16w20a, Minecraft 1.10.2, Minecraft 16w32a, Minecraft 16w32b, Minecraft 16w33a, Minecraft 16w35a, Minecraft 16w36a, Minecraft 16w43a, Minecraft 1.11 Pre-Release 1, Minecraft 1.11, Minecraft 1.11.2, Minecraft 17w06a, Minecraft 1.12 Pre-Release 7, Minecraft 1.12, Minecraft 1.12.1 Pre-Release 1, Minecraft 1.12.1, Minecraft 1.12.2 Pre-Release 1, Minecraft 1.12.2, Minecraft 17w43a, Minecraft 17w43b, Minecraft 17w47b, Minecraft 18w19b, Minecraft 1.13-pre3, Minecraft 1.13-pre5, Minecraft 1.13-pre6, Minecraft 1.13-pre7, Minecraft 1.13-pre8, Minecraft 1.13, Minecraft 18w30a, Minecraft 1.13.2, Minecraft 19w03c, Minecraft 19w07a, Minecraft 19w12b, Minecraft 19w13b, Minecraft 1.14.2, Minecraft 1.14.4 Pre-Release 5, 19w37a, 1.15.2, 20w07a, 20w10a, 20w11a, 20w14a, 20w18a, 20w19a, 20w20b, 20w21a, 20w22a, 1.16.1, 20w30a, 1.16.2, 1.16.3, 1.16.4 Pre-release 2, 1.16.4, 20w45a, 20w46a, 20w49a, 20w51a, 21w03a, 21w05b, 1.17.1, 21w39a, 22w03a, 1.18.2, 1.19.3, 1.20.4, 24w05b, 24w33a
    • Confirmed
    • Redstone
    • Normal
    • Platform

      The Bug

      When you send pulses into arrays of repeaters in quick succession, they will be lost.

      How To Reproduce

      1. Build setup as seen on picture
      2. Push the button
        → Notice how the signal travel through all the repeaters but the last one.

      (Note: this description uses “redstone ticks”, which are actually 2 game ticks long.)

      Note: It does not matter how long the array of repeaters is, you could have 500 and the last one would fail to turn off. This might have to do with updates, but when working with complicated or fast timing circuits, this bug is very annoying.

      On the right setup, a 1 tick pulse is generated when you place a redstone torch on the redstone block. It should give a 1 tick pulse to the piston, then turn off for 1 tick, and then give another 1 tick pulse. Instead, it gives a single 3 tick pulse.
      This is the most annoying of all when you have a large (downward) piston extender which can only be powered from one side, because you have to use redstone lines and to BUD a piston below another one, you have to send 2 pulses with 1 tick of delay inbetween.

      Code analysis

      Based on 1.11 decompiled using MCP 9.35 rc1

      The reason why the last repeater or comparator stays powered seems to be that the methods net.minecraft.block.BlockRedstoneDiode.updateState(World, BlockPos, IBlockState) and net.minecraft.block.BlockRedstoneComparator.updateState(World, BlockPos, IBlockState) set a different priority for the update based on whether or not a repeater or comparator is after them.

      —

      Newer code analysis by G4me4u foundin this comment.

        1. 2014-05-06_18.12.12.png
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        2. Pulsetest 1.png
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        3. Pulsetest 2.png
          Pulsetest 2.png
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        4. RepeaterBugWireFix.jpg
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        5. Rep-1.gif
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        6. Rep-2.gif
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        7. 2021-01-09_07.41.38.png
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        8. image-2021-10-03-12-30-27-446.png
          image-2021-10-03-12-30-27-446.png
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            Unassigned Unassigned
            dicotheredstoner DicoTheRedstoner
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              Created:
              Updated:
              CHK: