On Monday, February 28, 2011 09:52:59 am fi did opine: > On Fri, 2011-02-25 at 08:48 -0800, Kirk Wallace wrote: > > On Fri, 2011-02-25 at 15:46 +0200, fi wrote: > > ... snip > > > > > Is hal_parport.c the proper file to modify for 16 bit I/O over PATA > > > ports ? > > > Are other files to be modified ? > > > > ... snip > > > > >From my study of the parallel port drivers, 90% of the code is for > > > > setting up the structs for managing the setup strings, and sharing > > multiple ports. When that is out of the way, it comes down to a simple > > outb or inb to a few registers. I suspect the PATA interface might be > > the same except that 90% of the code will be PATA specific, so the > > parport code may not be helpful. > > > > If one is going to go through the effort of a new design, I would vote > > for pursuing a PLX based PCI or PCI-X interface like this one: > > http://wiki.linuxcnc.org/uploads/pci1_15_02_sch_wiki.pdf > > (from this page: > > http://wiki.linuxcnc.org/cgi-bin/emcinfo.pl?AVR ) > > > > (It seems to me, the old ISA slots would be perfect for real-time > > interfacing.) > > > > I am guessing here, but the only "active" part of the parallel port > > driver is in/outb which lives well with real-time. This may not be the > > case with PATA or PCI. Study of the PCI FPGA examples may shed light > > on this. > > > > On the other hand, if your time is money, just buying an existing PCI > > or PCI-X motion card would be cheaper. > > Hi > Regarding obsolescence, there are PCI/PCI-EXPRESS to IDE PATA adapters > which may already work > with pci_8255.c driver and 8255 boards but what I would love to get is > 16 bits wide I/O , so for now I'm looking at hal_skeleton.c and > hal_parport.c > > OTOH, > I used an internal PATA HDD Rack for some testing with _normal_ kernel. > I've played with some 573 574 and 245 , with 245(not being a latch) > were fast pulses which maybe are useful for fast steps in step/dir > configurations. > Next weekend I'll try a PCI to IDE adapter . > > > OT 1: is possible to make timing of step pulse to be half of desired > moving time like 1ms pulse for a 2 ms move or 3s pulse for 6s move? > Instead of many short pulses to give just a single pulse with half the > timing ? > EMC's stepgen knows before writing the pulse how long a move will take > so it will be easy for a modified step/dir servo to do optimized moves. > > OT 2: > I have bad latency PC's so here: > http://wiki.linuxcnc.org/emcinfo.pl?Latency-Test > it says: > "Numbers over 1 millisecond (1,000,000 nanoseconds) mean the PC is not a > good candidate for EMC, regardless of whether you use software stepping > or not." > Where we get in trouble with huge latencies is that in particular with steppers, when a huge lag hits, the motor which was stepping merrily along at 150 rpm, simply cannot come to a stop during the time the step signal was expected, and then resume that 150 rpm rate when the steps restart. Extremely high voltages and surge currents from the driver may help, but generally speaking it will likely overshoot a step or 4 getting stopped, losing its position reference, and will stall completely on the restart as it cannot accelerate back to that 150 rpm in one step.
>From a servo point of view, where the machine reads the encoders and evaluates the present position and issues corrective settings to the servos, which will blindly follow merrily along until the next such update, a huge latency could very well cause an overshoot. Carving PCB's, with traces 10 mills wide, aren't going to be 'pretty' although they may work without hand patching if its not too bad. OTOH, its not that hard to find hardware whose latency isn't that bad, and frankly the huge majority of that seems to be in the video drivers. I am absolutely forced to use the vesa driver regardless of the card installed in my milling machines box as its latency will be 50 times worse if I let it load the linux ati/radeon drivers. Ditto for when it had an nvidia card in it, even the linux nv driver was a latency disaster, and the nvidia driver itself, while it made good gfx using firefox etc, had 300+ millisecond latencies. The vesa driver has been the salvation driver for me. However, that older Mach-Speed mobo also has a built in video, using shared memory, and I think most of the people here have found the earlier implementations of onboard video have had to disable that, and waste a pci slot for an aftermarket card just to get rid of the shared memory problems. However, from reading between the lines on this list, the Intel DM510 boards are capable of working well with their onboard video. And the prices for new construction using that board are quite reasonable. > From a hobby point of view I don't care how much time it takes to mill a > good PCB as long as it is good ; so according to the statement above > I can't use EMC2 ? > I would not make that blanket statement. Good machines for EMC can often be had from the off-lease resellers at quite reasonable prices. Many of those are built like tanks & very dependable even as they age. > Sorry for my english I'd give a B+, you'll do fine. > Bye. > Florin > > > > > ------------------------------------------------------------------------ > ------ Free Software Download: Index, Search & Analyze Logs and other IT > data in Real-Time with Splunk. Collect, index and harness all the fast > moving IT data generated by your applications, servers and devices > whether physical, virtual or in the cloud. Deliver compliance at lower > cost and gain new business insights. http://p.sf.net/sfu/splunk-dev2dev > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users -- Cheers, Gene "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) <http://tinyurl.com/ddg5bz> Food for thought is no substitute for the real thing. -- Walt Kelly, "Potluck Pogo" ------------------------------------------------------------------------------ Free Software Download: Index, Search & Analyze Logs and other IT data in Real-Time with Splunk. Collect, index and harness all the fast moving IT data generated by your applications, servers and devices whether physical, virtual or in the cloud. Deliver compliance at lower cost and gain new business insights. http://p.sf.net/sfu/splunk-dev2dev _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
