Affordable 3D printer electronics with multiple interfacing possibilities: native USB, uSD, BT (with dongle). Top of the range FETs and direct fan control.

This 3D printer board electronics has been designed and developed using all the great contributions and feedback from the RepRap CloneWars group in Spain. All shortcomings from other similar boards have been addressed providing an affordable yet feature rich 3D printer electronics. The result, the SAV MkI.

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As soon as we achieve our goal, we will be releasing all the schematics and board layout, driving SW and housing to the community.

By contributing and supporting this project you are supporting the opensource maker movement and giving us that incentive to continue on our creative journey and community sharing.

We think that we can deliver a very competitive, high quality 3D printer controller board completely assembled and manufactured in Europe without skimping on components or manufacturing costs.

The boards proudly have the "Design in the EU" and "Made in Spain" credentials. By supporting this project you know what you will be supporting our local industry too. Why pay more for a lower quality product which is not even as feature rich as the SAV MkI?

A few ore specs about it would be useful.

It took me enlarging a photo to confirm that the design uses an Atmel AVR, and not say an ARM based core.

Since a sample board exists, I'd think that having at least a "preliminary - this may change" schematic up would not be asking a lot.

Going from the picture only:

1) I hope they get to the higher level of funding. Without their custom board, you may not have an LCD. That does not look at all like a normal LCD connector arrangement.
2) They might want to think about including some sort of Y cable for the Z axis. It does not look like there are two Z stepper connectors. A lot of these printers want 2 Z motors.
3) This looks like strictly a 12V design.
4) It's not at all clear what the fusing approach is. That would be a nice thing to know.
5) If the normal Arduino external boot loader stuff is on there, it's pretty well hidden. Again, something it would be nice to know about.

None of that says it's a bad design, or a bad board. Only that there are some things you might want to know about it before buying a couple of them. The LCD is something you would very much want to think about.

Thank you very much. Your suggestions are welcome.

Technical specifications, schematic and software details have been added to the documentation of the campaign.

Take a look

Thanks for putting up the schematic !!!

One thing I notice - you do not have a diode in series with the +5V 7805 regulator input. If you power the board from USB, and have no voltage on the +12, the 7805 will not be very happy ( = it will blow out). A 1N4001 is perfectly adequate as protection.

I do wonder why a lot more boards aren’t using the Atmel AT90USB1286, the Native USB interface is very appealing

Hi folks, thanks for the very good comments that you have all made.

I did consider putting an input protection diode but in this case I am relying on the diode within the the lm7805, the input diode on the USB and input and output caps. The circuit simply will take on the surge current when supplying it through the USB. Given that the voltage at the output is going to be less than 4.8V, the cap at the output will start charging and forward biasing the internal 7805 diode that will start charging the input cap once the input cap is charged, the internal diode of the 7805 will only carry the the cap's leakage current (very little).

The surge current transient is handle nicely through the 7805. It is not a fully protected if heavy loads are taken at the input. But with no load there it is more than happy with the input caps.

This board has been powered through the USB only for many nights without a single failure. A different story would be if you tried to power a load at the input. That would kill the 7805.

The USB transfer rates are incredible with this device. You can transfer gcode files to the uSD card reasonably quick to make it a useful feature. As opposed to going through the FTDI USB serial interface. At 8Mbps (about) the transfers don't take long and downloading an image to the device is very quick. I like that controller a lot and it is in a good range of my devices. The u32 is also one of my favourites.

The issue with the 7805 is that you can very easily have a load on the input to the device when you are powered off of USB. A fan set up for full time use, a light on the LCD display, even a pull down circuit on the +12 supply could all give you a load out there.

You could indeed. As a matter of fact that is what I have on my printer and nothing, the light are not even light at 4 volts and the fan doesn't consume much. I will try to pots a picture too with the power up transient. Very interesting to see too the steady climb in 60ms to 4V.
I will mark it for rev c of the board.

I'm starting to make the final modifications to the board that will become Rev C. All the modifications are minor but they sure will provide a good overall board with all your great inputs. I have taken a good range of suggestions from this thread and after talking to the fab house they are good with the mods:
- diode for the 7805 so that it doesn't work that much when not supplied at 12V.
- 2 rows of pins on the Z axis.
- an additional freewheel diode to the hotend FET.

The board already has it's entry in the RepRap's wiki:
http://reprap.org/wiki/SAV_MKI
With firmware upgrade instructions, configuration, ...

I hope you like it.

Thank you all for your contributions. It is making this board one of the best entry level electronics out there: simply connect and print. No need for heat sinks on FETs or FET replacements, great native USB transfer speed of gcode files to onboard microSD card for autonomous printing.

Any LCD/keyboard designed for the sanguinololu or teensylu will just work with the board.

Edited 2 time(s). Last edit at 12/10/2013 09:13AM by fmalpartida.

Great!! I already have mine!! Im going to help in the campaing anyway, this boards deserves it!!

Thanks Iceflow for supporting this campaign!