I’m upgrading my Ender 3’s main board to an MKS Gen L V2.0 and I want to wire a Max31856 Thermocouple board to it.

The Max31856 can use both software SPI or hardware SPI. Looking at the board’s SPI pins, this is what I think the wiring should be for hardware SPI. I’m a rookie when it comes to electronics, so can you guys chime in on if my wiring is correct? Text Max31856 Board MKS Gen L V2.0

Vin ------> any 5V pin

Grn ------> any ground pin

sck ------> D52

sdo ------> D50

sdi ------> D51

cs ------> D21

There are multiple possibility for the CS pin to connect to based on the main board pinout. So how do I make sure that Marlin knows which pin is being used? Also, for software SPI, it says that I can use any 4 available pins. Similarly, how do I define the 4 pins that I choose so that Marlin is aware? I know it’s within pins_RAMPS.h and pins_MKS_GEN_L_V2.h but I don’t know how to define each pin.

Lastly, are there any other changes I need to make in Marlin to complete my thermocouple board installation? Thanks very much for your time!


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