Here are some links to start:

http://blog.boxysean.com/2012/08/12/first-steps-with-the-beaglebone-pru/

http://www.element14.com/community/community/knode/single-board_computers/next-gen_beaglebone/blog/2013/05/22/bbb--working-with-the-pru-icssprussv2

On Friday, October 18, 2013 10:10:29 PM UTC-3, Paul Tan wrote:
>
> Thanks for feedback.  I didn't realize that linuxcnc was using the PRU.
>
> I will look into that code.
>  On 2013-10-18 6:46 PM, "Charles Steinkuehler" 
> <[email protected]<javascript:>> 
> wrote:
>
>> On 10/18/2013 5:22 PM, Paul Tan wrote:
>> > In case anyone's wondering why I'm trying to get really short pulses, 
>> I'm
>> > trying to connect an iGaging DRO slides to a BeagleBone Black (yeah, I'm
>> > trying to CNC my lathe using a DRO closed loop servo with my Dual Motor
>> > Controller Capes).  Scoping out my iGaging DRO, I found that the builtin
>> > controller uses 24uS pulses with a 128uS duty cycle.  I'm working off of
>> > Yuriy's work on the Arduino (
>> http://www.yuriystoys.com/p/android-dro.html),
>> > but trying it on the BeagleBone.
>>
>> For fairly short duration pulses like that, you may want to consider
>> using the PRU to handle generating the pulses.  It looks like the stuff
>> you're working from is already divided between the UI (handled by Linux)
>> and the low-level comms (handled by an Arduino).  Basically, you can
>> migrate the Arduino stuff to the PRU and probably have less overall 
>> hassle.
>>
>> I have some example code for step/dir pulses and PWM using the PRU
>> driving GPIO pins as part of LinuxCNC.  I also have some timing details
>> on PRU read and write latency when talking to the GPIO registers:
>>
>>
>> https://github.com/cdsteinkuehler/linuxcnc/blob/MachineKit-ubc/src/hal/drivers/hal_pru_generic/pru_generic.p#L135
>>
>> --
>> Charles Steinkuehler
>> [email protected] <javascript:>
>>
>> --
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