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Experimental MAX31865 on Marlin

Posted by achase79 
Experimental MAX31865 on Marlin
February 10, 2018 06:06AM
I liked the idea of a PT100 reader with 0.03 C resolution, and Adafruit already made the library available, so I quickly hacked support into Marlin if anyone is interested (I think there's currently a feature freeze, so I'll submit it later). Note that this only works for heater 0 (it piggybacks off MAX6675 support).

1. Get the Adafruit MAX31865 breakout board

2. Wire the board.
On RAMPS 1.4, Aux 2 top row = GND, 63[sdi], 40 [sck], 42 [sdo], 65 [cs]

If you want to change pin assignments, look for this line in temperature.cpp

Adafruit_MAX31865 max31865 = Adafruit_MAX31865(65,63,42,40); // Hardware SPI bricks LCD (?and SD)

2. Install the Adafruit MAX31865 library

3. Config.h

#define TEMP_SENSOR_0 -2 // MAX 6675
#define MAX6675_IS_MAX31865

4. Replace the temperature.cpp in your Marlin directory with the attached one.

5. Enjoy 0.03 C resolution!

I've trialed this for a month with no problems. However, do this at your own risk, and don't leave your 3D Printer unattended! I take no responsibility for whatever happens with your 3d printer.

The MAX31865 supports error handling, which has not yet been implemented. Also, hardware SPI doesn't play nice with the LCD, so currently it's bitbanged over extra pins.
open | download - temperature.cpp (71.7 KB)
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