There seems to be agreement that external hardware is the right solution
for motor control. What type of external hardware is somewhat dependent
on your target volume. The FPGA solution is nice in that you can buy the
hardware pretty reasonably from Technologic.
Be aware that Microchip has several PIC processors that are tailored for
motor control applications. It's been my experience that it is a _lot_
less work to get a sequential engine like a PIC processor to work than
it is to get a massively parallel engine like a Lattice FPGA to work.
YMMV, but in my circle of coders this view is pretty widely held. So if
you don't mind more work up front for lower running costs, the FPGA is a
good solution. If you don't mind higher running costs but want something
easier up front, a traditional microcontroller is probably best.
Of course, if Techologic offers a motor control core that works out of
the box the whole cost equation changes... This is a big IF.
I don't know how much power you need for your motors. If you are going
to have to have a custom driver board anyway, the microcontroller
solution won't be that expensive.
Jim Ham
Mark Featherston wrote:
>
>
> 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 <http://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 <ts-7000%40yahoogroups.com>,
>> Peter Gammie <> 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/
>> >
>>
>
>
>
>
>
> No virus found in this message.
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> Version: 2012.0.1913 / Virus Database: 2411/4924 - Release Date: 04/09/12
>
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