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We been through this before Jesse 1) I metioned nothing about realtime bit banging PWM 2) I've rightfully pointed out that the 7500 is much cheaper than the proposed 7520 in volume production 3) My comments specifically addressed how to do a high precision timer on the 7500 From: jesseoff <> To: Sent: Monday, April 9, 2012 6:46 PM Subject: [ts-7000] Re: high resolution timers and real time All I can say is that before anybody follows any suggestion of Walter on this list on "the proper way" to go about an important project using one of our boards, please give us a call first. 480-837-5200
Mark does indeed know what he's doing and when he's not sure on something, has access to a lot of other experts at TS that prefer to not enter online discussions. I've only briefly read this thread, but I can tell you the path of least resistance to reliable servo motor PID control does NOT involve realtime patches, kernel device driver writing, IRQ rerouting, high resolution timers, and software based realtime bit-banging PWM. Thats just absurd. //Jesse Off --- In , Walter Marvin <> wrote: > > Nonsense > > Linux handles real time quite well. Mark simply does not know how to do it properly > > Walter > > > > ________________________________ > From: Mark Featherston <> > To: > Sent: Monday, April 9, 2012 1:53 PM > Subject: Re: [ts-7000] high resolution timers and real time > > >  > Komal, > > I would not recommend going down the route of using kernel patches for high resolution timers in Linux for controlling a motor.  Linux is not well suited for hard realtime applications.  However, the FPGA on our boards is very good at meeting very specific timing like this.  We have created FPGA cores on the TS-7558-BOX and TS-7520-BOX with a common software interface which includes PWM control.  I would recommend migrating to one of these boards which can then use a very simple example: > http://www.embeddedarm.com//wiki/index.php/Daqctl#Controlling_a_Servo > > http://www.embeddedarm.com/products/board-detail.php?product=TS-7520-BOX > http://www.embeddedarm.com/products/board-detail.php?product=TS-7558-BOX > > > Best Regards, > __________________________________________________________ > Mark Featherston, Technologic Systems | voice: (480) 837-5200 > 16525 East Laser Drive               | fax: (480) 837-5300 > Fountain Hills, AZ 85268             | web: www.embeddedARM.com > > > > On Apr 2, 2012, at 12:39 AM, komal wrote: > >  > >Dear Sir, > > > >I have recently acquired a ts-7500 board with the development kit. The SD card comes with a 2.6.24 Linux Kernel. After a few days of experimenting I have realized that my application (controlling a servo through PWM) will require HRT and RT support which the Kernel is unable to provide (maximum timer resolution I am getting on the current Kernel is 20ms). > > > >I am new to Linux and embedded systems development and hence I am a little confused about how to tackle this problem. I do not understand what you mean by applying the patches and how to apply the patch. Can i simply do it on-board my board with the SD-Card. I have a windows PC with Eclipse for Development. > > > >Any help you can provide me will be highly appreciated. Thank you. > > > >Regards, > >Komal RAUF > > > >--- In , Peter Gammie <peteg42@> wrote: > >> > >> Charles, any anyone interested in hrtimers: > >> > >> With Andrew's help I managed to build a 2.6.32.3 kernel that seems to work. Attached are a config and a patch, based on this: > >> > >> http://lkml.org/lkml/2009/7/22/119 > >> > >> that enable hrtimers. I've lightly tested it on a ts7260 with 64Mb of memory. I loaded the kernel via TFTP with: > >> > >> load -r -b 0x00218000 -h 192.168.1.1 z > >> exec -c "console=ttyAM0,115200 ip=192.168.1.50:192.168.1.1:192.168.1.1:255.255.255.0:ts7200a:eth0:off root=/dev/mtdblock1" > >> > >> (i.e. no special memory options or anything.) > >> > >> So the routine is to apply Matthieu's patches, then this one. I expect it will apply to other kernel versions (specifically 2.6.29.6 if you want -RT) without too much bother - but be careful that the Kconfig patch applies to the right system type! > >> > >> As for the clock multiplexing, Charles's suggestion of using just a PREEMPT (not RT) kernel results in better behaviour under light periodic load (it doesn't flicker while running top on the console) but about the same under heavier load (scp'ing a few megabytes via ethernet). I have the CONFIG_NO_HZ (tickless) option set, which may or may not do anything in particular... > >> > >> So, more investigation is required. > >> > >> Thanks for all your help. > >> > >> cheers > >> peter > >> > >> > >> > >> > >> -- > >> http://peteg.org/ > >> > > > > > __._,_.___
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