I’ve been building a 3d printer for sometime now, and I’m ONLY using an arduino mega and repetier host. What I want to try is to control my 3d printer the way a ramps board would and creating similar ways of controlling the appliances (since i already have them all) the way the ramps board would.

I have 4 stepper drivers controlling the step and dir of each motor and connected into the arduino mega where the Ramp’s step and dir pins would have been, (based on Marlin firmware I’m using) except conneced directly on the arduino. so for the X axis: step pin - A0, and the dir pin - A1.For the Y axis step pin-A6, Dir pin-A7. For the Z axis : step pin-D46, dir pin-D48. And for the Extruder motor, step pin-D26, dir pin-D28. Will this work?

Next, I’m using 3 relays with transistors, one for the heated bed, one for the fan, and one for the extruder. the transistor Base pin would go to the arduino for on/off (HIGH, LOW) signals to switch on or off the “heaters” when required. So now I would connect the heated bed pin to pin D8 on the arduino, (again based on Marlin firmware), the the fan pin to D9, and the extruder pin to D10. will this work?

Now for the temperature sensors. I only have 2 one for the heatbed and one for the extruder. They are both 100k glass bead thermistors. Now there are 2 ways to connect or to read a thermistor.This is the Stein-hart method if i’m not mistaken:

And the other one is the Beta Factor method which is this :

Which one of them would the ramps have used? Or does it use some other method? If it does can someone tell me how to wire it it differently? I need to know this because I’m no using a ramps board, but I’m using the firmware, and I want it to be as if I were using one.

One more problem I’m facing is that whenever I power up my 3d printer, and connect it to repetier, My motors start rotating without giving any command, and my heatbed switches on and off (sometimes). Do I need to change the firmware? If I do what do I change and how.

One more thing is that the software reads the heatbed temperature and the extruder temperature to be at 100 degrees Celsius. (my thermistors aren’t faulty because I’ve changed the twice already and they gave the same problems.) What could be wrong?

I need to fix this because the software thinks it has reached the required temperature and will shut down the heaters.

Thank yo so much in advance,

Cheers, Mitch.

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