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by b0b0b
Sun Nov 03, 2013 12:52 pm
Forum: Raspbian
Topic: GPIO to SYSFS
Replies: 3
Views: 1418

Re: GPIO to SYSFS

So... how is it generated?
by b0b0b
Sat Nov 02, 2013 5:39 pm
Forum: Raspbian
Topic: GPIO to SYSFS
Replies: 3
Views: 1418

GPIO to SYSFS

Assume that the gpio X can be exported in sysfs as an input pin, after doing that a directory called gpioX will be created into /sys/class/gpio/. gpioX/ contains few file such as "value" which represents the current state of the gpio X (high or low). What happens (in kernel space) when the signal ap...
by b0b0b
Sun Oct 27, 2013 9:09 pm
Forum: Raspbian
Topic: GPIO registers and interrupts
Replies: 1
Views: 811

GPIO registers and interrupts

As I can read at page 90 http://www.raspberrypi.org/wp-content/uploads/2012/02/BCM2835-ARM-Peripherals.pdf GPIOs are mapped between 0x 7E20 0000 and 0x 7E20 00B0. GPIO Pin Level Registers (GPLEVn) contains every pin's value The pin level registers return the actual value of the pin. The LEV{n} field...
by b0b0b
Sun Oct 27, 2013 5:41 pm
Forum: Raspbian
Topic: GPIOs handling
Replies: 3
Views: 768

Re: GPIOs handling

Yes, I read it but it doesn't answer to my questions. I am trying to understand how OS handles GPIO pins. Considering sysfs, every kobject (e.g. GPIO) is implemented as a directory and each one of its attributes (e.g.: value, direction...) is represented as a file. So sysfs job is to map this "struc...
by b0b0b
Sat Oct 26, 2013 6:14 pm
Forum: Java
Topic: How can Java control GPIOs?
Replies: 4
Views: 15701

Re: How can Java control GPIOs?

Thanks clicky, BTW why would using sysfs be such a bad idea? Lets suppose that I have to handle 10 sensors connected to RPi, using only a polling mechanism would be a big waste of resources and maybe it can not guarantee to read all the sensor's value correctly. For example imagine to have a digital...
by b0b0b
Wed Oct 23, 2013 4:40 pm
Forum: Raspbian
Topic: GPIOs handling
Replies: 3
Views: 768

GPIOs handling

Hi all, I have few question regarding GPIO and linux kernel: - I know that in Linux everything is a file... I can access to GPIOs through sysfs, but how does that thing really works? I will explain it better. What happen when I do echo 30 > /sys/class/gpio/export and echo 1 > /sys/class/gpio/gpio30/...
by b0b0b
Wed Oct 23, 2013 4:29 pm
Forum: Java
Topic: How can Java control GPIOs?
Replies: 4
Views: 15701

How can Java control GPIOs?

Hi all, I would like to know how can Java control RPi's GPIOs... I mean Java is actually running on JVM and obviously it has to interact with the operative system in order to access to in/out pins. Is this interaction entirely based on sysfs? Or are there other ways (for example making a system call...

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