MicroCNC
I started a MicroCNC group on yahoo to design a micro based cnc controller.
http://groups.yahoo.com/group/MicroCNC/
It is now starting to look like it should be on here.
Going through my various micros and comparing capablities the prop won hands down.
It is still fairly new to me so I am on here asking for help.
Gavin
http://groups.yahoo.com/group/MicroCNC/
It is now starting to look like it should be on here.
Going through my various micros and comparing capablities the prop won hands down.
It is still fairly new to me so I am on here asking for help.
Gavin
Comments
I want to put more cnc machines in the shed without having to get more PCs, figured the Prop has enough grunt to do the axes control and maybe lots more.
Got the prop months ago but have only been using it a week and still learning it.
Learning the prop is taking a while but the more I learn the easier it is looking.
Just knowing other have done it means I can do it too[noparse]:)[/noparse]
The more information I collect the easier it should be.
Gavin
I may not be able to emulate an entire parallel port, going to need some other pins for video and keyboard etc.
If I make it configueable then with some restrictions it should be able to replace a Turbocnc, EMC or Mach pc.
You closed the loop with encoders? For a router that size you could have used servo drivers with step/dir input.
Have you got it taking G-codes or are you controlling it via a pc?
A two prop solution might get me the I/O for parallel port emulation.
One to replace the pc and the other as the stepper controller
Gavin
4 motor setup using Prop as step/dir source(alternative is the same, except step and dir is inputs from PC instead of outputs)
encoders 8 pins
step out 4 pins
dir out 4 pins
step rate to drivers 2 pins
disable to drivers 1 pin
subtotal Prop pins used: 19 of 32
Working on a 4 axis driver board design that may get changed to all in one if I can get prop doing what I want.
I was not going to let the prop control the microstep, just set it via dip switch, default to 1/8.
The great thing with the prop is all cogs have access to all pins, so limit inputs can become encoder inputs just by software change.
Want to use a jog encoder wheel to control single axis, so there will be at least one encoder input.
You could have a point about stepper encoders, when I get crashes it is a pain to reset zero.
An accurate home position could reduce the need for axis feedback.
Junk PC's don't worry me, I have boat anchors everywhere but space is limited in the shed and pcs love swarf.
Networking them would be nice, RS485? could do ethernet but why bother.
Hmm one prop for g-codeing another for motors, limits etc. Might be an easy way out than trying to fit it all in one prop.
Gavin
You will need more support for those rails [noparse]:)[/noparse]
The CNCmachne.jpg image really is attractive. I wonder how much one would pay for such?
Since Gavin mentions RS-485, you can go one step further to a CRC network.
I've been working with CANbus and the MCP2515 chip than can use the Propeller as its micro. I even made 25 boards and have gotten about 10 operational [noparse][[/noparse]it is an SPI interface and I've been using BasicStamps and SX-28s].
In other words, are you in need of an RS-485 communications capablity with allowance for multiple masters and 40 nodes? If so I am letting a pair of blank boards go at near cost $12USD via postal delivery world wide. A zip file of documents, PBasic test programs, and schematics is available. Just PM me.
I know this may seem like a blatant plug, but I am doing this at cost.
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"If you want more fiber, eat the package.· Not enough?· Eat the manual."········
I have visions of lying in a deckchair in the back yard while a bunch of machines are in the shed making money for me.
A wireless laptop to a pc RS-485 g-code server?
That dream is still off in the distance, I still need to get some speed curves working.
Starting to get a good picture of the box and what it can do.
Pretty much the same as this http://www.deskcnc.com/controller2nd.html
Wondering now why I am doing it, well why not, a good way to learn a new micro is to do something real with it.
Yeah I was thinking I was getting a lot of slop using the free air method!
A company called 8020.net cut the materials to order, the table alone is around $900 unassembled. I think the idea of sending the text file serially from one PC to multiple Propellers is interesting. Of course thee would be a file size limitation without external stotage. But, ifd you were going to go the the trouble to translate Gcode into steps, It may be worth the time to explore it. You could DL the file to the machines ID, then ready the machines individually with a few locfal buttons: Ref Home, Zero X, Y, Z, A, Jog each motor L-R, Front-Rear, Up-Down. Sop, Pause, Start. Just put a key pad on each machine with the buttons mentioned, or some other configuration.
Post Edited (originator99) : 11/29/2006 6:41:07 AM GMT
3D work and curved surface are a different story, but a large serial EEPROM should hold a few programs.
Local buttons are a good idea, small display for DRO, little serial LCD?
Would be nice if touch panel displays were cheap, easier to use something like a Z22 PDA.
Make a handheld pendant with LCD for manual control but also serial link to it?
Keep us posted on your progress Gavin.
I got extra dip props and eeprom when I ordered my prop kit, two of each incase one blows[noparse]:)[/noparse]
That looks like a milled pcb, Eagle and pcb-gcode?
Good reason for dip EEPROM is plugging in a bigger one later on, dip micro because it is easy to replace if faster one shows up.
What software tools are you using on the pc end?
Any thoughts on the serial comms protocol?
My first step is going to be getting linear velocity ramping working properly in assembly and get a single axis acting in a way that is comparable to what Tcnc or mach can do.
Graham
The board above is the barebones PCBexpress. Eagle to gcode is a slick option, I avoid making boards these days.
I'll send you a PM with a link to an app you can check out to talk to the Prop. I assume you have a PC with either a seral port or USB2serial adapter. Ther are some other goodies I can send you to check out.
Is you plan to generate gcode for a part, export the file to any number of machines each with a unique ID so the machine can be identified as to which one to dowload the file if on a network? If so, just a serial cable daisy chained between units will suffice. I don't remember what the max length is, but you could buffer at each link through a MAX3232, or just daisy chain the PC TX to all units. I don't see a big reason to need feeback, but if you did, you could find some method to get all machines to talk back to the PC, 1wire to serial off the PC and 1wire devices on each machine maybe.
Graham, what is the issue with getting ramping done in asm? What is the max step output capability for 3 motors using Spin? Unless you were micro stepping, I would think that Spin would be sufficient of using 3 cogs.
With servos you often need pulse rates that are pretty high especially if you are trying to go fast, one of my applications (a parallel kinematic machine) is all about speed.
Graham
Hexapod on the prop?
Re cnc mill
Not sure if it will need 1 cog for 4 axis or simpler to have 1 cog per axis with extra cog as controller.
If you get 1 axis working just copy it into another cog for another axis?
Nice stepper code here
http://www.embedded.com/showArticle.jhtml?articleID=56800129
How to use it in a multiprocessor environment?
So far it is taking me longer to learn prop/spin than it would to write the code[noparse]:)[/noparse]
Those Geckos have heaps of chips.
FPGA is one way to do it and is what I was looking at before finding the Prop.
I am still a beginner on the prop but it is nice to know others have already got motors spinning.
That's probably only about 5% of the entire project but it is the core part.
It should be good enough for simple home cnc machines.
Now a 4 motor 3 phase brushless controller with serial/IR/RC input would be fun.
As well as flying bots it would make a nice big router controller.
Nice little one for mini CDROM motors, nice big 500W one for industrial use.
Originator, how much do those Xbees weight?
If you are in the process of making a stepper motor driver please do it properly especially
if you are considering to sell the system to other people.
Implement short circut detection ( all possible modes) phase to phase .. short to gnd etc etc.
Desktop type cnc machines especially have depending on the mechanical construction and how the
machines moves its bed etc ..lots of moving parts ... cables flexing/moving...
Having worked in the industry for the last 10 years please take my word for it...
Some of those cheap drivers you can buy virtually explode when there is a simple phase fault..
Ronald Nollet
Parallax Australia distributor
Post Edited (Joe "Bot" Red) : 12/11/2006 3:41:27 PM GMT
I'm wondering if you could give me some more info on your setup, and what i might need to try using the propeller in this way.
Thanks so much!
~~Brian
how easy is the xbee to use with the propeller? and what hardware would i need to communicate between the prop and a computer? and finally, would it use the COM port behind my computer, or does the PC side have a usb connection (i hope).
~~Brian
I tried to find documentation on the Wi232DTS for comparison, but couldn't find a good link.
The XBee is real easy to use with the Propeller - Simply use FullDuplexSerial just like you would with a COM port at 9600.
I have boards to plug the XBee into a breadboard/solderboard, though they require 5V for operation, they can interface directly to the propeller at 3.3V (though I can modify for 3.3V power if needed). In about 2 weeks I'll have full 3.3V board available for a little less in SIP version or to go on the new Propeller ProtoBoard headers.
As far as the PC side, I also have USB adapters for the XBee's that create a virtual COM port.
http://www.selmaware.com/appbee
-Martin
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Martin Hebel
StampPlot - Graphical Data Acquisition and Control
AppBee -·2.4GHz Wireless Adapters & transceivers·for the BASIC Stamp & Other controllers·
Post Edited (Martin Hebel) : 1/8/2007 6:14:44 PM GMT
this looks perfect, i'll look into it in more detail. any hints on the PC side of the txfr?
~~Brian
No, it can't be used for wireless programming directly at this time. The XBee does not support remote DTR control, and I don't think the Propeller IDE would care for the latency either.
If that's your need (I came in at the end of the discussions) I don't think this will fit what you need.
-Martin
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Martin Hebel
StampPlot - Graphical Data Acquisition and Control
AppBee -·2.4GHz Wireless Adapters & transceivers·for the BASIC Stamp & Other controllers·
Mike
~~Brian