[MCPE-15607] Pistons take 3 redstone ticks to extend and 1 tick to retract, which should both take only 1 rs tick Created: 17/Jun/16  Updated: 27/Sep/17  Resolved: 19/Jul/17

Status: Resolved
Project: Minecraft (Bedrock codebase)
Component/s: None
Affects Version/s: 0.15.0, 0.15.4, 0.15.6, 0.15.10, 0.16.0, 0.16.1, 0.17.0.1, 0.16.2, 1.0.0.0, 1.0.0.1, 1.0.2, 1.0.3, 1.0.4.1, 1.0.4.11, 1.0.5.3, 1.0.7.0, 1.1.0.9
Fix Version/s: None

Type: Bug
Reporter: PHO
Resolution: Works As Intended Votes: 20
Labels: game-tick, piston, redstone, redstone-tick, redstone-timing

Attachments: JPEG File IMG_0447.JPG     PNG File slow-piston.png    
Issue Links:
Duplicate
is duplicated by MCPE-14687 Behind the piston due piston is retra... Resolved
is duplicated by MCPE-15071 Pistons are working too slowly Resolved
is duplicated by MCPE-15219 Sticky pistons not working properly Resolved
is duplicated by MCPE-15601 Takes to long until you can close/ope... Resolved
is duplicated by MCPE-17406 Very slow pistons. Resolved
is duplicated by MCPE-20961 Pistions and Sticky pistons are slower Resolved
is duplicated by MCPE-21271 Piston timing bug Resolved
is duplicated by MCPE-21789 Pistons don't extend other pistons. Resolved
is duplicated by MCPE-26165 Piston timings are slow and VERY inco... Resolved
Relates
relates to MCPE-15044 Redstone lamps do not turn off immedi... Reopened
relates to MCPE-12848 Comparators measuring a container tak... Resolved
relates to MCPE-15793 Redstone components don't apply the c... Reopened
relates to MCPE-15476 Stuck pistons stay stuck forever Resolved
relates to MCPE-15736 Sticky Piston won't pull Slime Blocks... Resolved
Confirmation Status: Confirmed
Platform: Tablet - iOS - iPad 3
CHK:
ADO: 24797

 Description   

The screenshot shown below is a falling-edge detector which should emit 2 ticks pulse on a falling-edge and shouldn't emit a pulse on a rising edge.

The repeater is set to 2 ticks delay. On a rising edge the piston should take 1.5 redstone ticks to extend so there should be no pulse emitted from the output. On a falling edge the piston should retract instantly (0 redstone ticks) so there should be 2 ticks pulse from the output.

However in 0.15.0, pistons take 2.5 or 3 redstone ticks to extend and 1 or 1.5 redstone ticks to retract, so the said circuit instead acts as a 1 tick dual-edge detector.

According to a developer, it might be a result of the redstone circuit ticking separately from the block entities (piston). During the 2 tick: Redstone ticks first, which will propagate the repeater. The piston ticks afterwards placing the moving block as full block.



 Comments   
Comment by PHO [ 19/Jul/17 ]

Thank you Helen but I don't think that is correctly explaining the behavior because the circuit always emits pulses of the same length and not randomized. However, I just found the following modification perfectly fixes the problem so this turned out to be in fact another instance of MCPE-15793.

So yes, the ticket can be safely closed either way.

Comment by Helen Zbihlyj [ 19/Jul/17 ]

This was closed by the design team as works as intended.
Explanation below:
"It takes exactly 2 rTicks to retract, but because the pulling piston starts retracting (toggleMechanismTiming example) at that same tick, the ticking order is scrambled (as designed) therefore the result is undefined."

Comment by Zeb [ 30/Apr/17 ]

Revised title to be more accurate to what the intended piston timings are for Bedrock Codebase.

Comment by PHO [ 13/Jul/16 ]

I suspect that this one and MCPE-12848 stems from the same root cause.

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