# How to Make a RPM-Time Chart Using Hall Effect

**URL:** <https://discourse.nodered.org/t/how-to-make-a-rpm-time-chart-using-hall-effect/15122>\
**Category:** General\
**Created:** [4 September 2019 19:28 UTC](https://discourse.nodered.org/t/how-to-make-a-rpm-time-chart-using-hall-effect/15122 "2019-09-04T19:28:08Z")\
**Posts on this page:** 7\
**Page:** 1

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**Author:** ![george](https://avatars.discourse-cdn.com/v4/letter/g/71e660/32.png) [@george](https://discourse.nodered.org/u/george)\
**Post date:** [4 September 2019 19:28 UTC](https://discourse.nodered.org/t/how-to-make-a-rpm-time-chart-using-hall-effect/15122/1 "2019-09-04T19:28:09Z")

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I currently have a Raspberry Pi 3, a hall effect sensor and a magnet attached to a bicycle's wheel. I'd like to make a real-time RPM vs Time chart that shows the gradual decrease of the wheel's speed (in RPM). but I don't know where to start because I'm still a beginner at node-red and coding in general. Something similar to the graph in the picture I included but with the RPM value instead of the temperature. Any help is appreciated!! [temperature-vs-time-phase-change-graph|690x492](https://discourse.nodered.org/uploads/short-url/1zK20WoXgIk1ZnMoMpnl2ocSFcz.png)

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**Author:** ![Colin](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/colin/32/17040_2.png) [@Colin](https://discourse.nodered.org/u/Colin)\
**Post date:** [4 September 2019 19:50 UTC](https://discourse.nodered.org/t/how-to-make-a-rpm-time-chart-using-hall-effect/15122/2 "2019-09-04T19:50:49Z")

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The first thing to do is to break the problem down into parts then tackle them one at a time. Since you have not given us any hints I presume that you are starting right at the beginning, in which case the first thing to do will be to connect the sensor to the Pi and then pick up the signal in node-red. Do you know how to do those two things?

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**Author:** ![george](https://avatars.discourse-cdn.com/v4/letter/g/71e660/32.png) [@george](https://discourse.nodered.org/u/george)\
**Post date:** [6 September 2019 13:18 UTC](https://discourse.nodered.org/t/how-to-make-a-rpm-time-chart-using-hall-effect/15122/3 "2019-09-06T13:18:59Z")

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Yes I connected the sensor to the Pi's Gpios.However I am totally unaware of what to do to pick up the signal in node-red. My only experience with node-red is creating a temperature chart using the Sense-Hat sensor in the past.But As I said i need to do the same thing(a chart) but using the Hall Effect sensor to measure the wheel's speed. Id be grateful if you could help me step by step.

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**Author:** ![ukmoose](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/ukmoose/32/13_2.png) [@ukmoose](https://discourse.nodered.org/u/ukmoose)\
**Post date:** [6 September 2019 13:29 UTC](https://discourse.nodered.org/t/how-to-make-a-rpm-time-chart-using-hall-effect/15122/4 "2019-09-06T13:29:15Z")

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You need to research how to read the hall effect sensors data on a RaspberryPi.  
Different sensors use different methods, of connection. Only you know what sensor you have.

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**Author:** ![george](https://avatars.discourse-cdn.com/v4/letter/g/71e660/32.png) [@george](https://discourse.nodered.org/u/george)\
**Post date:** [6 September 2019 13:37 UTC](https://discourse.nodered.org/t/how-to-make-a-rpm-time-chart-using-hall-effect/15122/5 "2019-09-06T13:37:27Z")

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Hello my friend and thanks for your response. I have this sensor right here. [sensor](https://grobotronics.com/hall-sensor-board.html)

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**Author:** ![afelix](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/afelix/32/9743_2.png) [@afelix](https://discourse.nodered.org/u/afelix)\
**Post date:** [6 September 2019 14:26 UTC](https://discourse.nodered.org/t/how-to-make-a-rpm-time-chart-using-hall-effect/15122/6 "2019-09-06T14:26:22Z")

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So if you click through on those links it shows you the user manual, the datasheet and even software to connect to it. Which of those have you tried so far? The user manual goes as far as explain how to connect it and explain how it works, explain how to set up a serial connection to it and at what baud rate/other configuration. Have you tried that yet? Otherwise have you checked out the linked datasheets to see what they explain about connecting to it and how to read the values?

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**Author:** ![system](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/1X/d073cd938eafa2e558d7c2cd59003b3ef4963033.png) [@system](https://discourse.nodered.org/u/system)\
**Post date:** [14 April 2020 18:23 UTC](https://discourse.nodered.org/t/how-to-make-a-rpm-time-chart-using-hall-effect/15122/7 "2020-04-14T18:23:37Z")

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