I have the software working for Fans, Bed, Extruder, Steppers, Endstops, thermisters. In short everything I need to use the board. I have not yet tested Auto level or filament sensor. All functions working on the LCD. Will go through a print on the bench, will exercise all steppers, heaters and the fan. The PID functions nicely on both heaters. The Raspberry Pi camera tested and working. Using the firmware: Install the "arduino-1.8.9-windows". Unzip the "Working Arduino.zip" Go into the Arduino folder then into the Marlin folder. Double click on "Marlin.ino". You are now in the firmware and ready to load onto the Arduino board. Click on tools and set the port and verify that the board is a genuine Mega Arduino. Only those boards work. Click on the right arrow on the top bar to load the firmware. If it does not load reboot and try again. Attached is a picture of a working / not working / and untested / Arduino Board. Auto level is verified as working. Link for Marlin file: https://drive.google.com/open?id=1kfGce8RplWiVw3_gPpxhKlYaDzd7pvjN I modified the Marlin file to always return the same value for Raspberry Pi current that the Robo R2 returns. I did this because the Arduino board has no chip monitoring current and the floating pin will give random results. I have built a Robo printer that uses dual Z steppers and dual Z switches. It is set up for 3950 thermisters on both bed and print head. Link: https://drive.google.com/open?id=15LGnDVBA9oADLHWf-lUng-pYtP7frPka video of progress: https://drive.google.com/open?id=1zGXZr7gJl-D9rE4K4kLu4ZzLZCgnDnNO Filament sensor solved. The Arduino does not do the filament sensor the Rasberry Pi does through the red and black wires coming off the header. The wires come from GPIO (20/21) and run up to the sensors. I assume GND comes from the ribbon cable. This should just work. I modified the Ramps board: remove D1, move the 5amp PTC into the 11 amp PTC position and replace the 5amp PTC with a fuse holder (11amp fuse) The original code was modified to reassign the Bed to D9 and the Extruder to D10, and the fan to D8. I have included a zip of the working code. D9 and D10 are now 24 volts for the heaters and D8 is 12v for the extruder fans. I have included below a mark up of the Arduino that shows the hookup. The 5v regulator on the Arduino can not handle the current. I am using a 24v->5v step down (eBay $2) that powers both the Rasberry Pi and the Arduino. You have to make the Arduino power cable from a micro USB cable. The Arduino cable uses standard two pin connectors. The 12v no longer has much current so I use a step down 24v->12v, the 12v is less than 1amp with all fans on full.