Hello every body
I plan to use the beaglebone and i'd like to know to to set a GPIO bit
in input, output and interrrupt.
Is there any body to help me ?
Thank's a lot
i am french so you can answer in french if you want
How would you like to set them? Using a linux shell script? A C program? Via a kernel module?
I can help you with most of those, but I need more information.
Been following this as I’ve been trying to do much the same. What would be really helpful to those of us just getting started would be some code examples (hopefully both in C and a scripting language like bash, perl, or python) on how to firstly how to configure/reconfigure the punmux post boot (including I/O direction and what to do if anything on change of state), and secondly how to do simple things once the pinmux is set such as working with single or groups of gpio pins, having devices show up in /dev as appropriate (for example when the pinmux brings out tty3, /dev/tty3 ought show up), using i2c, spi, serial, and gpio and how these things are accessed. That would go a long way toward getting started. as for compiled, scripted, or kernel module, each likely has it’s place - personally I just want to start getting work done and have some fun with it and as of yet, I haven’t found the resources to make that happen.
Eric
If you get the kernel source (either download it or look on kernel.org)
and look in the Documentation directory, you will find a file called
gpio.txt, this explains in great detail how access is made to GPIO
pins.
There is a set of library calls you can make, or you can use the
/sys/class/gpio directory to access the pins as files (this is described
at the end of the document).
David
I will make a script soon that details how GPIO can be accessed via the shell and make a short document that hopefully straightens things out.
I'd like to see examples of how it's done in Cloud 9 since it's part of the default configuration of the Beaglebone. We'd probably call the library, but we just don't understand how it's configured, what settings to pass to the library, etc..
I think a good example of this might simply be a row of LED's that can be managed by the bone.. Or a couple of servo's.. Or maybe even a few sensors of some sort.... These would give examples of the different ways the GPIO can be used.
bonescript.js has a table that lists many of the gpio pins, mux settings, etc. I found that very helpful.
wjr
Hello.
Here is a sample in shell script.
https://github.com/joelagnel/validation-scripts/tree/master/bone-tester/lib
Mux settings in bonescript/index.js, I can't get input value.
Once I wrote 0x37 (Receiver enable/pullup/MODE7) to
/sys/kernel/debug/omap_mux/*,
then I've got input value.
Masato.
Here's a python script to blink LED USR3:
import time
with open('/sys/kernel/debug/omap_mux/gpmc_a8', 'wb') as f:
f.write("%X" % 7)
with open('/sys/class/gpio/export', 'w') as f:
f.write('56')
with open('/sys/class/gpio/gpio56/direction', 'w') as f:
f.write('out')
with open('/sys/class/gpio/gpio56/value', 'w') as f:
f.write('1')
time.sleep(1)
with open('/sys/class/gpio/gpio56/value', 'w') as f:
f.write('0')
time.sleep(1)
with open('/sys/class/gpio/unexport', 'w') as f:
f.write('56')
Check out this link for more info:
http://www.gigamegablog.com/2012/01/05/beaglebone-coding-101-blinking-an-led/
Lots've good info in this thread thus far.
However, does anyone have C-code based example for flashing the User
LEDs / toggling GPIO ?
(ie. flashing User LEDs from compiled C-code rather than doing this
with Python script/Java Script/shell commands....)
Hi,
Lots've good info in this thread thus far.
However, does anyone have C-code based example for flashing the User
LEDs / toggling GPIO ?
(ie. flashing User LEDs from compiled C-code rather than doing this
with Python script/Java Script/shell commands....)Here's a python script to blink LED USR3:
import time
with open('/sys/kernel/debug/omap_mux/gpmc_a8', 'wb') as f:
f.write("%X" % 7)
with open('/sys/class/gpio/export', 'w') as f:
f.write('56')
with open('/sys/class/gpio/gpio56/direction', 'w') as f:
f.write('out')
with open('/sys/class/gpio/gpio56/value', 'w') as f:
f.write('1')
time.sleep(1)
with open('/sys/class/gpio/gpio56/value', 'w') as f:
f.write('0')
time.sleep(1)
with open('/sys/class/gpio/unexport', 'w') as f:
f.write('56')
Well, in C you use open/write/close, but otherwise it's the exact same
sequence of stuff. are you just asking somebody to translate the
python to C? Seems pretty straight forward.
If you're looking for an actual API, I wrote a gpio driver which
reflects the kernel's gpiolib API into user space.
http://wiki.gumstix.org/index.php?title=User_GPIO_Driver
It's not gumstix specific and will work for any kernel which supports gpiolib.
A couple of good sources for the basics of writing C code for the
Beagleboard and Beaglebone are:
- the Embedded Beagle Class. http://elinux.org/Category:EmbeddedBeagleClass.
Here is a direct link to C code that toggles GPIO pins:
http://www.rose-hulman.edu/~yoder/Beagle/exercises/gpio/togglegpio.c
- the web site for the book USB Embedded Hosts http://www.lvr.com/beagleboard.htm.
It has various C language examples, including one that flashes the
USER LEDs.
Dan.
We are writing the code in C as of now and it works but cannot find the fastest PWM or GPIO rate possible. Thank you for the resources. Our bone is up and running from the git-go without any problems in an embedded controller app.
I made a small post regarding basic file system GPIO which can be found here:
http://akademii.blogspot.com/2012/02/beaglebone-gpio-testing.html
I hope to put more material up on how to manipulate GPIO in C in both User and Kernel space. I have a kernel module built so if someone really needs help before I can make a post, feel free to reply.
Simply using echo from the shell?
http://platformx.sourceforge.net/Documents/nuts/HowToGPIO.html#GPIOs
from Command Line
I am not sure what you ment but the blog discribes specifically how to
toggle GPIO from the shell using the default image shipped with a
BeagleBone.