Quote Originally Posted by bobe99 View Post
Nice design!

I was wondering on the physical connection and whatever Marlin changes are necessary.

In Marlin, my guess is that we need change MOTHERBOARD from 33 to 34.

That translates to the following physical connections on the Ramps 1.4 board:

  • D10 = Hot End #0 (12v)
  • D09 = Hot End #1 (12v)
  • D08 = Heated Bed (12v)
  • D11 = Servo (5v)
  • D04 = PLA Fan (12v)


My questions (assuming the above is correct):
  1. What Fan Expander are you using? I see one from Makerfarm which states it exposes D4/D5 and one from Geetech which exposes D6/D11.
  2. Regardless, how is the servo connected? The Geetech usurps all of the servo pins and only directly (via pin headers) exposes the 4 fan pins (D4/D5 or D6/D11) and 2 pins for an external voltage source. I cannot find any info on the Makerfarm version (other than the description supplied on the Markerfarm website), but the Geetech has schematics that clearly show a common MOSFET gate voltage. So my question is how does this thing power both the 5v servo and the 12v fan though either of these gizmos? I mean, how does either of these adapters handle both a 5v servo and 12v fan?
  3. Can you supply all of the Marlin changes you have made? E.G. Any changes in pins.h? Any changes to support the belt systems?


I'm really skeptical of the Makerfarm fan expander (just due to the lack of documentation, no photo of the other side of the board and the off-hand comment implying it does not provide a buffer between the ramps and fans).
Yes. The connections are all correct. I'm using the MakerFarm fan extender, which is manufactured by RepRapDiscount. It has a dual buffer driver and a jumper to provide 12v power. It has two fan channels, on D4 and D5, but it covers all four servo pins. I soldered a header with three pins to the D11 pins on the top of the fan extender, and that's where I plug in the servo. The only connections on the board are D4/D5, so the other two are available--just covered. It would be awesome of they used a wire wrap socket so the pins extended out the top for this purpose.

I didn't make any changes to the firmware. I can check my local repo and provide my config files later tonight. I'll also upload my custom GCODE. I don't have access to that machine right now.