Can't control fan using Reprap Ramps 1.4 RRD Fan Extender

Hi!

After spending hours and hours going through the search results on the Googly thing, flashing the firmware and trying stuff out, I don't know what to do. I'm using a Fabrikator Mini bought from HobbyKing, and I'm trying to add a software controlled fan using the Reprap Ramps 1.4 RRD Fan Extender. Fabrikator Mini uses a MKS Base v1.3 board, although I've seen another Mini with a 1.4 board. Anyway. I've tried M42, M106, M107 and whatnot, but the fan is always on at full speed. According to the almighty interwebs, servo pins should consist of all digital pins (at least D2 and D4), but mine has D12, D11, A12 and A11. A pins are probably analog, so they can't provide PWM, and PWM is all I want.

What do I need to do to get it working?

So apparently you have one of these [github.com]
As all earlier board don't have a servo type connectors

D12 and D11 are both PWM pins

M42 P11 S255 and M42 P12 S255 should work

You have wired the expanded correctly? Ie the two pins go to 12v and the 4 pins in a row are for the two fans ?

Update... I see the issue

If you compare the ramps servos pins to the MKS BASE pins you will see gnd and +5v are reversed

ie [reprap.org]

On a ramps the pins for each servo are data pin,+5v and gnd
On the MkS BASE is data pin, gnd then 5v

This board will not work by directly plugging it in to a MKS BASE board

Edited 2 time(s). Last edit at 04/19/2016 07:15PM by Dust.

Quote
Dust
So apparently you have one of these [github.com]
As all earlier board don't have a servo type connectors

D12 and D11 are both PWM pins

M42 P11 S255 and M42 P12 S255 should work

You have wired the expanded correctly? Ie the two pins go to 12v and the 4 pins in a row are for the two fans ?

Update... I see the issue

If you compare the ramps servos pins to the MKS BASE pins you will see gnd and +5v are reversed

ie [reprap.org]

On a ramps the pins for each servo are data pin,+5v and gnd
On the MkS BASE is data pin, gnd then 5v

This board will not work by directly plugging it in to a MKS BASE board

The RRD Fan Extender I'm using requires an external 12 V source, so I don't think it uses the 5 V at all. I'm not sure though. If I hook it up to the baseboard's 12 V input, the fan will stay on at full speed no matter what I do.

The extender only has two controllable outputs. Is it possible that the extender's pins are wired to the analog pins instead of the digital ones? I need to check this out. How are the pins mapped in software? I mean, do I need to define something in Marlin or does "M42 P11" always mean digital pin 11, and P12 digital pin 12?

Your controller board is applying 5v to the ground rail on the fan extender because it is wired with gnd and +5v swapped compared to the ramps.

no the extender doesn’t normally use the 5v, in fact the 5v rail on the servo plugs is actually disconnected on the ramps, until you jumper it to vcc, so even if it tried to use 5v it wouldn’t get any.

If you look at


You can clearly see the track going to d11,d12 at the top

You can also see the ground track on the last pin bottom row of the connector

If you lucky you can just cut this track.

What you need to do is with a multi meter check if any of those bottom row of pins in the image are connected to that last gnd pin (while the extender is not plugged into anything)
If none of the other 3 pins are connected to the 4th pin your good.
Cut the ground track near the connector
Strip off a bit of the remain track so you can solder to it
Solder on a bit of wire to that track to the last middle pin (ie move the gnd connector up one pin)
Plug it into your controller (while off!!), check with a meter that there are no shorts from the 2 and 3rd rows (ie a short from +5 to gnd)

should work after that.

NB I take absolutely no responsibility if this blows up, its up to you to check it makes sense and nothing is shorted.

Edited 4 time(s). Last edit at 04/20/2016 08:13AM by Dust.