On Wed, 29 Aug 2012 14:05:26 -0500, Charles Steinkuehler wrote: > -----BEGIN PGP SIGNED MESSAGE----- > Hash: SHA1 > > On 8/29/2012 11:49 AM, Lars Segerlund wrote: >> What I was thinking is do the kinematics on the PC and just dump >> positions per axis on the avr ..... point in time and space so to >> speak .... it should work to stream to it ... >> >> I mean it's an open loop system ? > > Yes, it's an open loop system, driving step/dir stepper motor > controllers that have no feedback (ie: missed steps ruin your print). > > There are folks doing the math on the PC. The bottleneck then > becomes > the serial communications link to the AVR, so there is work in > progress to support g-code files with some form of binary compression > so the thousands of little line segments can be sent quicker. The > Arduino *IS* connected via USB, but there is an actual serial link > running at apx. 1 MBit/s or so on the AVR that limits the ultimate > speed: > > Google Groups thread about hacking compressed G-code for Rostock: > > https://groups.google.com/forum/?fromgroups=#!topic/deltabot/NI9WrN1Vmio > > IMHO getting LinuxCNC to do the math *AND* drive the steppers seems > like a much better overall solution. I realize some hardware would > be > required, but folks in the RepRap world are already buying hardware, > with a pretty typical setup listed below. Note that the designs are > open source and there is enough volume in these parts that the > Chinese > are direct selling through e-Bay and drop-shipping straight from the > orient: > > Arduino AVR controller board: $25-80 > > http://www.ebay.com/itm/Arduino-MEGA2560-ATmega-8U2-ATMEGA2560-16AU-USB-Cable-/270970778895?pt=LH_DefaultDomain_0&hash=item3f171df50f > > RAMPS 'shield' board to interface the Arduino to the printer: $50-80 > > http://www.ebay.com/itm/RAMPS-1-4-electronics-SD-RAMPS-and-cables-RepRap-3D-printer-/170902524785?pt=LH_DefaultDomain_0&hash=item27ca959371 > > Qty 4-5 Polulu stepper motor drivers: $10-15/ea > > http://www.ebay.com/itm/4-x-A4988-stepper-driver-pololu-compatible-3D-printer-reprap-prusa-mendel-/150871293385?pt=LH_DefaultDomain_2&hash=item2320a13dc9 > > Note: First price is Chinese e-bay, second price is US/EU sourced. > > A LinuxCNC based solution would still need the stepper motor drivers, > but that leaves $75-$150 to create an interface board to connect a > parallel port to some thermistors and high-current 12V FET switches > (all of which except for the A/D converters is on the RAMPS board).
When I was contemplating a similar solution I was thinking of going with either a NURB or a B-Spline with some information about the initial, max, and exit velocities implemented on the hardware. a 6D+ spline with extra motion primitives could describe the equivalent of a one or more g-codes. EBo -- ------------------------------------------------------------------------------ Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ _______________________________________________ Emc-developers mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-developers
