Printing completely wirelessly - can it be done? (Has it already been done?)

I just had a brain-wave, which I am keen to try out.

I have successfully installed and tested my SD RAMPS on my RAMPS 1.4, and it works great. I can upload gcode files to the micro SD card, and use Pronterface to pick one for printing, start the print job, and disconnect the USB cable and let the printer do its stuff.

However, I still have to start the job with a physical USB cable link between my laptop and my printer.

In my previous Arduino-tinkering, I have used a pair of wireless XBee modules [littlebirdelectronics.com] to create a wireless serial link between the Arduino and my laptop. Functionally, it works just like a physical cable, but it will work over a distance of 20 - 50 metres or more. In principle, provided I can access the right pins (assuming there are enough free pins on the Arduino Mega), it should be possible to set up an XBee wireless link from my RepRap in my workshop to my laptop in my lounge room, so I can initiate print jobs and monitor them from anywhere in the house. The gcode files would be on the SD RAMPS memory card, so I am not sending a heap of data over the wireless link while printing - just monitoring the print run. (I don't even need to monitor continuously - break the link, and the print should just carry on.)

The only real hiccough I can think of (apart from the physical job of accessing the necessary pins and installing suitable headers) is that with my current set-up, if I reconnect the USB cable mid-print, it seems to re-boot the Arduino and stop the current print job. Are other people seeing this problem, and is there any way to reconnect the Arduino / RAMPS back to the host software (Pronterface in my case) without interrupting the print job?

What do people think? Is it workable? Has anyone already tried?

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Follow my Mendel Prusa build here: [julianh72.blogspot.com]

Here an article on using bluetooth with RepRap.
[reprap.org]

Not very well documented, but it looks like it can and has been done.

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My Reprap blog

jds-reprap.blogspot.com

You can prevent the arduino from resetting when you connect your usb cable by putting a capacitor between gnd and the reset switch (as described here). Not sure whether this is feasible on a RAMPS board as I don't have one - I have built my RAMPS electronics on a solder-pad board so there is room to make such mods. I have it connected via a removable jumper. When the jumper is on, the cap is connected and the arduino won't get reset via the usb. When the jumper is removed, you get normal behaviour. It is advisable to make the connection switchable as the arduino program uses the auto-reset functionality when downloading new firmware.

CeeThreeEs Wrote:
-------------------------------------------------------
> You can prevent the arduino from resetting when
> you connect your usb cable by putting a capacitor
> between gnd and the reset switch (as described
> here). Not sure whether this is feasible on a
> RAMPS board as I don't have one - I have built my
> RAMPS electronics on a solder-pad board so there
> is room to make such mods. I have it connected via
> a removable jumper. When the jumper is on, the cap
> is connected and the arduino won't get reset via
> the usb. When the jumper is removed, you get
> normal behaviour. It is advisable to make the
> connection switchable as the arduino program uses
> the auto-reset functionality when downloading new
> firmware.


Thanks for the info! If it is a hardware issue, it probably won't matter over a wireless (XBee) connection, as there won't be any actual physical connection between the Arduino and the PC.

I'm planning to have a go at jury-rigging an XBee to my RAMPS this coming weekend to see if I can get my machine to talk wirelessly to my laptop. I already have all the hardware I need (I think), and I think I have identified the pin-outs I need to access on the RAMPS board to connect to my XBee. I'll probably have to hack the Sprinter firmware as well to change the baud rate (currently set to 115200; my XBee defaults to 9600); I'm not sure what baud rate will work well with both devices, Pronterface software, etc.

I'll report back here as to how I go.

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Follow my Mendel Prusa build here: [julianh72.blogspot.com]

I have managed to get my Arduino (with RAMPS 1.4 attached) to talk wirelessly to my PC using XBee with a simple test program, but I can't get Pronterface to talk to the RAMPS (with Sprinter) via the XBee.

I can't attach the XBee shield in the usual way (i.e. stacking shields on top of each other) because it is only a standard sized shield, not a Mega shield, so I can't put it between the Arduino and the RAMPS, and it won't piggy-back onto the back of the RAMPS.

Basically, I have attached the XBee shield to the RAMPS board by attaching 4 pins on AUX-1 (namely, 5V, Gnd, D1 and D0) to the 5V, Gnd, Rx and Tx pins on the XBee Shield. This was sufficient wiring to get the Arduino Mega to talk to the PC for my XBee test program. The XBee shield is getting power, and seems to be "alive" (lights are blinking, etc).

However, when I attempt to attach Pronterface (having re-installed the Sprinter firmware first!), I am getting messages in the console window that I don't understand, and I can't connect Pronterface to the RAMPS:

Traceback (most recent call last):
File "C:\RepRap\Pronterface\kliment-Printrun-6af04ed\pronterface.py", line 115
2, in connect
self.p.connect(port,baud)
File "C:\RepRap\Pronterface\kliment-Printrun-6af04ed\printcore.py", line 59, i
n connect
self.printer=Serial(self.port,self.baud,timeout=5)
File "C:\Python27\lib\site-packages\serial\serialwin32.py", line 30, in __init
__
SerialBase.__init__(self, *args, **kwargs)
File "C:\Python27\lib\site-packages\serial\serialutil.py", line 260, in __init
__
self.open()
File "C:\Python27\lib\site-packages\serial\serialwin32.py", line 56, in open
raise SerialException("could not open port %s: %s" % (self.portstr, ctypes.W
inError()))
serial.serialutil.SerialException: could not open port COM5: [Error 5] Access is
denied.

Would anyone who actually understands these sorts of things like to chime in with an opinion? For example, do I need to hook some more wires from the Arduino / RAMPS to the XBee shield, or am I attempting the impossible?

Back to USB / SD-RAMPS for now, until I can figure this out.

Edited 1 time(s). Last edit at 11/19/2011 05:08AM by julianh72.

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Follow my Mendel Prusa build here: [julianh72.blogspot.com]

DOH!!!!!
I had the UART / DLINE switch on the XBee Shield switched to DLINE instead of UART. (No, I don't know what it means either! I just know you have to have it switched to DLINE to upload new sketches to the Arduino by USB cable, and UART for wireless comms to work.)

Flicked it back to UART, and it seems to be working perfectly - I can now drive my RepRap from another room!

Full details and video on my blog: [julianh72.blogspot.com]

Edited 1 time(s). Last edit at 11/19/2011 08:58AM by julianh72.

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Follow my Mendel Prusa build here: [julianh72.blogspot.com]

I've done a similar thing but using Bluetooth (cheapest module I could find was $8 shipped!!!).

Unfortunately the first module I bought was not ok, so I had to buy another one to get it working ok.

Details are available (RAMPS with Bluetooth) [fightpc.blogspot.com.es]