doing real time things in userland dont work well. Using the PWM is the best way to step motors
On 11/13/2016 4:33 PM, Chris M wrote: > > > 4) playing with stepper motors - Python > > > I first mimicked the bonescript to us the GPIO pins to run the stepper > motor. I noticed I could run it faster than I could with bonescript, > but would still get the same issues just at better speeds. I then > tried setting the pin to run as a PWM output. > > ISSUES FOUND: > USING GPIO is not a good solution for running stepper motors. > > Issuing the mrraa.write(0.xx) would cause a buffer overrun when > setting the PWM duty cycle and crash the program, > Using pin.pulsewidth_us(xxx), pulsewidth_ms(xxx), or pulsewidth(x.xx) > to set the duty cycle directly would work, but when values got out of > range the pwm chip would become locked requiring the BBG to have to be > reset.. > > SOLUTION: > > 1) false trail. Upgrade the mraa library (the BBG came with v 0.95) > to version 1.5.x. this was pretty tough for an absolute beginner like > me. Needed swig3.0, which can be installed using debians dpkg. Need > Cmake which was somewhat difficult to get an image of with out having > an sd card. it took some time to get it installed. mraa installs files > in sys/local/lib vs sys/lib like cloud9 expects to see. Once mrraa was > installed, i had to correct ly place a few files to get it to work, > but mraa 1.5 would fail to initalize pwm on the pins, I dont know why > as using mraa commands to check the pins always returned correct > values, but it still failed. > > 2) current state. I bought a micro SD card and installed the latest > BBG image on the eprom. This came with mraa1.0. Still all the BBIO > python examples are junk. You no longer get a buffer overrun using > mraa.write(), but you can still lock up the pwm. > > End entry 4 > > > On Sunday, November 13, 2016 at 4:09:06 PM UTC-6, Chris M wrote: > > Some thoughts and findings as I begin to learn the BBG (Beaglebone > Green) > > -- > For more options, visit http://beagleboard.org/discuss > --- > You received this message because you are subscribed to the Google > Groups "BeagleBoard" group. > To unsubscribe from this group and stop receiving emails from it, send > an email to beagleboard+unsubscr...@googlegroups.com > <mailto:beagleboard+unsubscr...@googlegroups.com>. > To view this discussion on the web visit > https://groups.google.com/d/msgid/beagleboard/6611fa64-374e-48ae-b64b-5b41d749592e%40googlegroups.com > <https://groups.google.com/d/msgid/beagleboard/6611fa64-374e-48ae-b64b-5b41d749592e%40googlegroups.com?utm_medium=email&utm_source=footer>. > For more options, visit https://groups.google.com/d/optout. -- For more options, visit http://beagleboard.org/discuss --- You received this message because you are subscribed to the Google Groups "BeagleBoard" group. To unsubscribe from this group and stop receiving emails from it, send an email to beagleboard+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/beagleboard/02bc4a37-ebcf-ba08-87c3-f9e09b68bcf1%40gmail.com. For more options, visit https://groups.google.com/d/optout.
