# SDA SCL 5V GND different power supply; errors

**URL:** <https://discourse.nodered.org/t/sda-scl-5v-gnd-different-power-supply-errors/78541>\
**Category:** Hardware\
**Created:** [19 May 2023 13:27 UTC](https://discourse.nodered.org/t/sda-scl-5v-gnd-different-power-supply-errors/78541 "2023-05-19T13:27:46Z")\
**Posts on this page:** 3\
**Page:** 2

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**Author:** ![jbudd](https://avatars.discourse-cdn.com/v4/letter/j/5f8ce5/32.png) [@jbudd](https://discourse.nodered.org/u/jbudd)\
**Post date:** [20 May 2023 00:03 UTC](https://discourse.nodered.org/t/sda-scl-5v-gnd-different-power-supply-errors/78541/21 "2023-05-20T00:03:41Z")

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> [@TotallyInformation](#):
>
> There are, however, several reasons to prefer a microprocessor board for sensors/relays over a Pi.

Yes I agree.  
My preference is ESP8266 microcontrollers. About £2 and since there is no physical connection, no chance of frying "your $35 (~ £100) micro computer".  
I should have said "I don't understand why people use Arduinos for jobs like this".

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**Author:** ![Sean-McG](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/sean-mcg/32/54677_2.png) [@Sean-McG](https://discourse.nodered.org/u/Sean-McG)\
**Post date:** [20 May 2023 01:21 UTC](https://discourse.nodered.org/t/sda-scl-5v-gnd-different-power-supply-errors/78541/22 "2023-05-20T01:21:28Z")

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The inputs to the pi should be 3.3v.

If you have an i2c device powered from 5v there is a good chance that it will pull SDA and SCL up to 5v and damage your pi.

To test disconnect the sensors SDA and SCL wires from the pi and measure the voltage coming from the sensor, if its more than 3.3v you should use a level converter.

The best option is to power all the sensors from 3.3v if possible.

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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:** [19 July 2023 01:22 UTC](https://discourse.nodered.org/t/sda-scl-5v-gnd-different-power-supply-errors/78541/23 "2023-07-19T01:22:02Z")

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Closed on 19 July 2023 01:22 UTC

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