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Max31855 Configuration

3ghendricks3ghendricks
in Repetier-Firmware
Arduino Mega
Ramps 1.4
RepRapDicount

2 Extruders
2 type K thermocouples with MAX31855

So after starting into 3D printing a week ago I am now trying to configure my Ramps to allow for 2 thermocouples.  I have read everything I can find but nothing really explains how to hook up the MAX and how to set the inputs.

I used the configuration tool to set the temperature sensors for MAX31855 and the pin assignments to Analog 10 and 12

I have the Max hooked up as follows

Vin -- AUX-2 5V
GND -- AUX-2 GND
DO -- AUX-3 MISO
CS -- AUX-2 A10
CLK -- AUX-3 SCK

I am only trying to get one to work first then I thought I would parallel the common pins and use AUX-2 A12 for the other CS on thermocouple 2.

So far it doesn't give a reading, does anyone have information about how this is done?


Comments

  • RAyWBRAyWB
    edited May 2017
    Think you fried the devices....

    refer MAX31855 Datasheet :

    https://cdn-shop.adafruit.com/datasheets/MAX31855.pdf

    They are not useable on 5V Systems ....
  • 3ghendricks3ghendricks
    Okay I will try the other one with 3.3, the back of the board even says, "Vin: 3-5VDC"  There is a pin that says 3.3  I'll just voltage divide down to that one. 

    Any ideas on pin configuration in the firmware?
  • RAyWBRAyWB
    ok, i saw different types of the breakout board , some with the level shifting , some without, but both sold as 3-5V :-(

    so may be you can send a link with picture of the board.

    configuration  in Configuration.h

    search for:

     #define SUPPORT_MAX31855  (should not be commented)

    sensortype should be set to 102



    as far as i can see the max 31855 support uses Hardware SPI  , so on ramps it would be aux3 , cs to pin53

    (just took a look to development code)   so may be you check cs on 53 first  , seems only 1 of the 31855 supported

  • 3ghendricks3ghendricks
    edited May 2017
    It's an Adafruit MAX31855,  I have the LCD on the AUX3 ports, will this interfere?  That's why I was wondering if AUX2 could maybe be used.

    http://imgur.com/a/5Q4ju

  • RAyWBRAyWB
    edited May 2017
    so on the adafruit board level shifting is done, no problem.
    take care, 3v pin on this board is OUTPUT. don´t use it.

    aux 3 is occupied by sd-card...
    mosi,miso and clk can be used multiple(on avr), cs not
    so just don´t plug in the sd, use pin53 for cs and just see what happens
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