# Gpio causes bouncing, don't understand debouncer
**URL:** https://discourse.nodered.org/t/gpio-causes-bouncing-dont-understand-debouncer/99750
**Category:** General
**Created:** [22 November 2025 11:06 UTC](https://discourse.nodered.org/t/gpio-causes-bouncing-dont-understand-debouncer/99750 "2025-11-22T11:06:33Z")
**Posts on this page:** 4
**Page:** 1
### Author:  [@Aziona](https://discourse.nodered.org/u/Aziona)
#### Post date: [22 November 2025 11:06 UTC](https://discourse.nodered.org/t/gpio-causes-bouncing-dont-understand-debouncer/99750/1 "2025-11-22T11:06:33Z")
I have a water flow sensor connected to 3.3v and ground on my RPi3. If the water is low the the rpi-gpio IN node shows 1.
If the water is high it fluctuates quickly between 0 and 1. How should I use Debounce nodes to show 0 when it is quickly fluctuating between 0 and 1?
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### Author:  [@Aziona](https://discourse.nodered.org/u/Aziona)
#### Post date: [22 November 2025 13:07 UTC](https://discourse.nodered.org/t/gpio-causes-bouncing-dont-understand-debouncer/99750/2 "2025-11-22T13:07:34Z")
It might be that I do not need a debouncer. I found the following on AI:
**Important Note on Pull-ups:** The Raspberry Pi GPIO pins usually have built-in **pull-up or pull-down resistors**. For a float sensor connected to **Ground (GND)** and **GPIO 17** , you should ensure the GPIO is configured with a **PULL-UP** resistor. This keeps the voltage **high (1)** when the contacts are open (low water) and makes the voltage **low (0)** when the contacts are closed (high water).
After I set the Resistor value in the Node to Pulldown it seems to give a steady 0.
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### Author:  [@edje11](https://discourse.nodered.org/u/edje11)
#### Post date: [23 November 2025 14:47 UTC](https://discourse.nodered.org/t/gpio-causes-bouncing-dont-understand-debouncer/99750/3 "2025-11-23T14:47:44Z")
It depends on what type of switch is in the water flow sensor.
If it's equipt with a hall sensor no debounce is required.
If there's an reed contact or similar like that debounce is required. Most of the time debounce of 20ms is enough.
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### Author:  [@system](https://discourse.nodered.org/u/system)
#### Post date: [7 December 2025 14:48 UTC](https://discourse.nodered.org/t/gpio-causes-bouncing-dont-understand-debouncer/99750/4 "2025-12-07T14:48:20Z")
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