date:20140702

Re: [beagleboard] Re: PRU GPIO and voltage levels

2014-07-02 Thread Sungjin Chun

Thank you for your answer; I've used my own kernel module for pinmuxing,
now, instead, I have another option for this task.


On Wed, Jul 2, 2014 at 2:47 PM, TJF jeli.freih...@gmail.com wrote:



 Am Mittwoch, 2. Juli 2014 00:34:11 UTC+2 schrieb Sungjin Chun:

 Can I pinmux in PRU? The TRM says I have to be in privileged mode to
 write pinmux register.


 You need to be in priviged mode to switch on the PRUSS (ie echo PRUSSDRV
  /sys/devices/bone_capemgr.9/slots).

 Once the PRUSS is running, there's no kernel software between the PRU and
 the pinmux registers. So the answer is yes, the PRU can do pinmuxing in
 privileged or unprivileged user mode.

 Test the examples in libpruio to see this happen on your system

- *button* configures an GPIO input pin with high resistor
- *stepper* configures four output pins
- *sos* unlocks the user LED3 to control this GPIO pin

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[beagleboard] Re: Installing phpmyadmin on Debian version 2014-05-14 - Help

2014-07-02 Thread Giovanni Santini

I'm not that expert, but the tips I could think to are:
- have you already PHP and MySQL installed? (would be better from Debian 
repos)
- which IP you used? I'd suggest to use localhost/127.0.0.1
- check your firewall settings to allow traffic on TCP 80 (standard 
websites (HTTP) port)
- check that phpmyadmin is symlinked in the correct folder; if you 
symlinked to */var/www* shouldn't it be in the main webroot?

Il giorno mercoledì 2 luglio 2014 06:16:10 UTC+2, Stacy Cottles ha scritto:

 I am struggling accessing phpmyadmin. I have installed the package as well 
 as created a symlink in /var/www but I get an error each time I go to 
 http://ip-address/phpmyadmin. Any tips or tricks I could use?


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[beagleboard] Re: Assessing BeableBone Black capabilities

2014-07-02 Thread Fisher Grubb

Thanks TJF and Mechael,

Thank you very much for your input, yes, I'm asking lots of questions
because the board I will choose, I will use for maybe the next 3 or more
years and it may also be used for other projects at the university.

Sorry, I have a few more questions, hopefully I can clear up the main
things and make my choice.

Thankfully there seem to be more options for powerful mainstream hobby
boards (starting with the Pi, now the Beagle boards and Cubie etc), so I'm
trying to understand the differences, are there any more boards I should be
considering?. I'm hoping to clear some things up so I can finish my
comparison report, it might be nice to have a comparison wiki for it to be
easier to see the differences and people can more easier choose a board
that suits their project.

There is a wikipedia page that is detailed for certain things, not for
others and not all filled in, but a good start:
http://en.wikipedia.org/wiki/Comparison_of_single-board_computers

For the PWM, I read that the hi resolution (eHRPWM) can do 2 outputs, can I
control 2 motors with one eHRPWM unit?

TJF, what do you mean about different modes when you referred to PWM? Is
this to do with multiplexing pins/ports or PWM function modes for either
the eCAP or eHRPWM units? Are there modes for other features besides PWM?

I have found 2 pages which state that the board has 8 PWM outputs, though
on the BeagleBone page, I see 14 pins, most are A and B outputs of the
HRPWM units, can they all do individual PWM outputs? How can I work out
how many motors I can separately control? Would be very nice if I can
individually control 2 motors for each HRPWM unit (maybe same frequency but
different duty cycles for A and B pins).
http://beagleboard.org/Support/bone101
http://section9.choamco.com/2012/07/beagleboard-vs-beagleboard-xm-beaglebone-vs-raspberry-pi/

7 ADC channels should be more than enough for me, nice that they are 12
bit, what max sample rate can be used? The AM355x Ti datasheet states that
the ADC can do 200 thousand samples a second, is this correct?

I get the feeling that certain features of the chip have not been
implemented in software, is the PRU the only one or are there others? What
other items need implementing or improving? I have read about someone
complaining that the PWM under usual circumstances is limited to 100Hz due
to a kernel bug.
http://stackoverflow.com/questions/23050738/beaglebone-pwm-limited-to-100-hz

I read some people complaining about the Anstrom distro that comes
installed, I also read on the elinux.org BBB page that the BBB project will
move over from Angstrom to Debian, is Debian or Ubuntu fully functional?
What do most people use?

So it seems that the PRUSS or PRU-ICSS (depending where you read what its
called) may not have all its features implemented, is that correct? Have
things mainly been implemented according to what the person making the code
wanted it to do?

If I choose this board, my main reason may be for the PRU subsystem, I may
end up contributing to projects to either fix or implement certain
features. How can I easily understand what PRU features are completed and
fully functional vs ones that need work or are not even implemented?

Sorry for all the questions, I have not found a page which has this
information together, would be nice to feed this sort of info back to the
BBB main site.

I almost didn't hear about the 2 IO processors in the PRU because its not
in the AM355x datasheet, just mentions PRU with nothing that made me
realise how useful it could be.

Fisher

On Wednesday, 2 July 2014 03:50:48 UTC+10, Michael M wrote:

Hello Fisher. TJF gave some good answers. I'd also add that:

Are there BBB python libraries for general things like PWM, ADC, I2C and
other general IO like in RPi?
-Adafruit_BBIO is really good and well-supported

How different is the BBB to use and program to RPi?
-Since they both run linux, in general programming them is the same. The
BBB uses the Device Tree/Cape Manager system which can make the initial
learning curve a little steep... not sure if the RPi uses Device Tree by
default.

The BBB seems to have 2 x IO processors in its PRU-ICSS, I think they
are 200MHz each, how easy is it to use them for inputs, outputs and
calculations separate from the CPU? Is there a kernel module?
-Once you get the workflow set up, it's pretty straightforward to use them
for IO. The main processor is probably better suited for calculations.

The PRU-ICSS does not really seem to be documented except for in a GIT
project, the documents there seem to have info from Texas instruments (who
make the CPU) but not official. Is this subsystem used by others? How?
-I've seen it used for 3D print motion and heater control, CNC motion
control, etc. Knowing that most instructions take 5ns gives you extremely
precise timing... you can have your own high-resolution timers, generate
PWM,

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