Heating with D8-D9-D10

Dear community,

I am using Arduino Mega and RAMPS 1.4 for creating a custom control (without using MARLIN) for the extruder. I am using a Dyze Design Pulsar which is using 3 heaters. I have connected respectively to the D8, D9 and D10 ports. In my code I have a PID which is managing the 3 temperature sensors and heating independently the 3 heaters. The issue is that at the beginning all the 3 heaters should turn on and I am raising up all the 3 pins with digitalWrite(). The issue is that only one effectively is working. It could be a problem to turning up all the 3 together?

Also I have notice that in all the RAMPS that I have D9+ and D10+ are shorted.

Thank you so much

D8, D9 and D10 are all low side switching.

What that means is the that positive side is always connected to the supply voltage.
The negative side is switched. Connecting and disconnecting gnd.

If you connect any of these floating gnds to real gnd anywhere then that mosfets are bypassed and the circuit is on.


Secondly Power. On the ramps the power rail is split into two parts the 5 amp and the 11 amp sides



The 11Amp provides power to the D8 mosfet only
The 5 Amp provides power to D9 and D10 (and everything else needing 12v)

Edited 1 time(s). Last edit at 05/31/2022 09:24PM by Dust.

Thank you! I was missing the second power supplier. Because in the other ramps (the 1.6) there isn't the second supply and confused me. Thank you!