A few PT100's and MAX31865

Using Arduino Sensors
1

Hi,
I'm newbie in Arduino and here. ::slight_smile:

I'm going to measure temperature by using RTD (PT100) and MAX31865 converter.

But, I have to use about 5(five) PT100 sensors.

So, the questions are:

  1. Is it possible? :astonished:
  2. How many MAX31865 converters I need to use, five?
  3. If I use five MAX31865, so how they all communicate by SPI with Arduino.

Thank you... :wink:

2

Is this a bare chip, or a breakout board.
Link?
It might have a CS (chip select) pin.
Leo..

3

Hi, Leo! :slight_smile:

Yes, it it a chip, 700-MAX31865AAP+,

Link to web page

and

MAX31865 datasheet

Juri..

4

No experience with this chip, but it has a CS (chip select) pin.
That can be used to select one chip on the same bus.

That CS line is also available on breakout boards.

Leo..

5

Hi guys,
As i can see, some of you have some experience with Max31865 RTD-to-Digital IC.
I'm designing a board with 12 converters.

My doubt: it is necessary to use DRDY pin ? I need to read the state of this pin to trigger an interrupt, maybe ?
Whats the real purpose of the DRDY pin ?

Thanks.

6

My doubt: it is necessary to use DRDY pin ?

No, you can leave it disconnected. You just need to wait out the conversion time, vs waiting for it to go active & signal the conversion is done.

I put 15 on a board with none of them connected.

Try this sketch from Maxim for reading 1, put it in a loop to cycle thru all 12.

You have to put real #s in these 2 lines:

float Reference_Resistor; //Reference Resistor installed on the board.
float RTD_Resistance; //RTD Resistance at 0 Degrees. Please refer to your RTD data sheet.

This uses DRDY, adjust to wait it out if you don't use it.

max31865Hani.ino (9.97 KB)

7

I'm using a breakout board supplied by a company called playing with fusion it has 2 pt100/1000 inputs and has code on the site www.playingwithfusion.com

8

CrossRoads:
No, you can leave it disconnected. You just need to wait out the conversion time, vs waiting for it to go active & signal the conversion is done.

I put 15 on a board with none of them connected.

Try this sketch from Maxim for reading 1, put it in a loop to cycle thru all 12.

You have to put real #s in these 2 lines:

float Reference_Resistor; //Reference Resistor installed on the board.
float RTD_Resistance; //RTD Resistance at 0 Degrees. Please refer to your RTD data sheet.

This uses DRDY, adjust to wait it out if you don't use it.

Have you run this code on an Arduino and does it work