What do I have to do to make the MAX318 MAX31865 RTD PT100 Amplifier run on 3.3V?

Using Arduino Project Guidance
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Hi, this is my first post so I am sorry if there are any wrongdoings.

I am currenting trying to build a setup for work where I can read the water pressure of a valve via the Gravity Water Pressure Sensor (Gravity__Water_Pressure_Sensor_SKU__SEN0257-DFRobot) and read the temperature of a cooler via a PT100 in combination with a MAX31865 shield, simultaneously.

The good thing is that I managed to have both running on their own seperately.
However, I realized that they both run on a 5V VIN, and unfortunately my Arduino Uno only has one single 5V output. Now, I am not sure if I should/can tweak some setting in the code for the MAX31865 to have it run on the 3.3V output (which is currently not occupied), since the wiki states that this module has to be run on the same voltage as the voltage for the logic (and Arduino uses 5V logic, right?)

So, what are my possible options? I could only come up with scaling up the 3.3V to 5V, but if I am not mistaken that also requires another reference voltage of 5V, which I also dont have.

Any help would be appreciated.

Best regards,
Alex

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Splice two wires together, to connect to the one 5V output. Be sure to stay under the ~150 mA limit on the current you are allowed to draw from it.

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Have you read the data sheet for the MAX318 it states:"Supply Voltage Range (VCC to GND)...................-0.3V to +4.0V" The NAX31865 says: Voltage Range on VDD Relative to GND1............-0.3V to +4.0V". To answer your question nothing.

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There is 5V available on the IOREF pin.

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Many of the Arduino's such as the UNO and NANO have 3V3 available for low current external devices. As for the SPI interface you can use a level shifter. At this point I would highly recommend you get a copy of the Arduino Cookbook, then skim it cover to cover and read the sections important to your project. Also download the data sheet: https://www.analog.com/media/en/technical-documentation/data-sheets/max31865.pdf and read it, it tells you all about the part.

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With a 5V Arduino like the Uno, you need a MAX31865 breakout board compatible with 5V I/O, such as this one, and power it with 5V.

Ignore @gilschultz uninformed comments, and post a link to the MAX31865 board you have.

unfortunately my Arduino Uno only has one single 5V output.

Why did you post in the Portenta forum category?

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Sorry for the category, that was a mistake. As for the board I have, I have exactly the kind you linked in your reply, I have the Pt100 version. Pinouts | Adafruit MAX31865 RTD PT100 or PT1000 Amplifier | Adafruit Learning System. I think splicing the cables would be a good idea, and I am going to start with that idea.

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Follow that Adafruit tutorial and you should be fine.

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