The First problem:-
I have an Anet A8 and have been trying to update the hardware to Marlin. Which I think I have done. When I switch on the printer the display shows ‘Marlin 1.1.9’. Only the X, Y and Z are flashing ‘0’ and ‘?’. If I auto home they read X -33 and Y -10. Now if i rest them to say X 100, Y 100, Z 0 and save, the display shows that (X 100, Y 100, Z 0). Now if I do a Home the head moves back to where it was at the start and not to the new setting. The display shows X -33 Y -10 Z 0. I tried to rest the home over and over and it still wi9ll not set to the centre of the bed. I have tried to set Home using Pronterface and Simplify 3D but it will not set. When moving to Home back to the same place (X 100, Y 100, Z 0).
I have installed a SN04-N censer. So I need to set Home to the centre of the bed so as to set it up.


Next is I uploaded Marlin using Arduino 1.8.5 from my laptop. Now it seems to have uploaded all ok but for the flashing X,Y,Z. So I looked on the web to find out how to set home in Marlin. Again total confusion as most of the help is for Skynet and not Marlin. So I tried to upload Marlin again with Arduino and it will not upload as it finds and error in the compiling. pasting “/* SPI Master In Slave Out pin*/” and “_DDR” does not give a valid preprocessing token. So now I tried to upload Marlin from my Desktop, again using Arduino. This time I get a different error. #error “Oops! Make sure you have ‘Arduino Mega’ selected from the ‘Tools -> Boards’ menu.” Now if I set this printer then Marlin will not upload as it say set to Anet A8. OK so I re-downloaded both Marlin and Arduino for the laptop and the desktop. Now i get the same Error on both, pasting “/* SPI Master In Slave Out pin*/” and “_DDR” does not give a valid preprocessing token
Do any of you have any ideas as I am running out of hair and reaching the stage where I thinking of a new Motherboard (maybe with Marlin in it). I’m sorry for such a long post, but I been fighting this for the last 5 days. Please HELP

Hey! So, for auduino upload you need the Anet bboard installed, just google ‘anet marlin github’ and select the link for githubs marlin guide for anet, it’ll show you a few things like I think you may have uploaded the wrong marlin variant, (it’ll show how to build anet-marlin) and the github guide will have a link to the boards too. I’d link but am omw out rn!

I have used the ‘Anet Marlin Github’ download and added Anet to Auduino hardware folder. and i still get an Error :- error “/* SPI Master In Slave Out pin*/” and “_DDR” does not give a valid preprocessing token. Or the error “Oops! Make sure you have ‘Arduino Mega’ selected from the ‘Tools -> Boards’ menu.”

This a bug of the C preprocessor that some Arduino and some PlatformIO environments are using. Just remove the comments (// onwards) and it will compile and work…

Credits go to GitHub