Completely autonomous electronics?

Hi all.

The usual way to have a RepRap know what to print, is to have it attached to a PC.
Even if you are printing from an SD card, the PC is still here to order the print.

What about a completely stand-alone setup - no PC or RPi or other purchase-only device to give orders?
Was it ever done?
If so, what problems were there?
If not, why not?

I was making my own electronics for my Prussa i2, so i designed them to be autonomous from the start.
The basic design is similar to Sanguinololu - ATMega644 core.
The main difference is the addition of buttons and a screen.
The files to print are stored on an SD card.
Runs a butchered variant of Sprinter firmware (Arduinoless, bootloader updates firmware from a file on the card)

That's what it looks like, in a crude prototype:


Simple four-button interface for all controls, simple menu-based LCD.


You can move the axes and toggle the heater:


You can select the file for printing:


And then have a status as it goes:


Pause, abort, all the conveniences.

Now, the purpose of me telling this is - is it worth making and publishing, or should it stay a private project?
Is anyone interested in having electronics like that?
So far it suffices for me, but for public use it'll have to be cleaned up.

I was planning to etch a dedicated PCB for it, to free up the breadboard:


A version of it to use the popular Polou boards and like would be necessary.
The firmware also needs refining to be presentable.

Would all this be worth the trouble, or is there a reason no one does it this way?

That sort of setup exists and is quite common - I use a 4x20 lcd, rotary encoder and sd card setup with marlin firmware, and my reprap is not tethered to my pc. Admittedly I do have to connect it to flash new firmware, but I hardly ever do this, and I need a pc anyway to generate the gcode and move it to the sd card. The self-flashing firmware would still be a very neat addition to the marlin firmware if you wanted to share your code though.

The software would be quite design-specific.
I can post one for the Sparkfun's Nokia5110 screen ( [www.sparkfun.com] ), but i have no idea if it's something common.
Making it a front-end for Sprinter/Marlin is straightforward - there is little intersection between the internals of the GUI and the backbone, you pass commands by sending them into the buffer, and it can use the SD card already.

The bootloader is firmware independent, and is nothing special - just google avr sd card bootloader.
No idea how to integrate it with the Arduino software, however.


I guess the initial question is kind of pointless, so i'll just dump the designs here, free for anyone to use.
The main board: [orbides.1gb.ru]
The streamlined 1.4 (classic L298+L297) stepper driver: [orbides.1gb.ru]
These are schematics in Eagle.
Important note - the main board schematics say 5 volt and 7805, but it's really 3.3V, or the SD card and the screen would fry.

The software it runs on: [orbides.1gb.ru]
Butchered version of Sprinter 1.3.something, and an SD card bootloader based on PetitFS FAT driver..
No heated bed controls in either - i have a separate circuit for it.

Feedback is welcome, btw. I have no idea how sane the PCB layout or the whole design is.


Finished up PCB.


Works nicely so far.
If no problems show up, then the machine is out of initial development stage, and into the infinite development one


One more note - don't ever attach a breadboard to anything with a lot of double-sided tape.
The damage is repairable, but it's still a mess:


Edited 2 time(s). Last edit at 03/31/2013 05:18PM by Artlav.