GPIO Interrupts

[Cosik]

Hi,

Did anyone run external interrupt support in C/C++, successfully?

[Stinde]

I have implemented a simple GPIO counter using Linux interrupt counters in /proc/interrups. SW was in C.
This method can be used only for counter. If you need something more complicated I can't help.

BR,

Timo

[Cosik]

Hi,

It will be nice if you could share with us some code part. I'm still looking for solution.

[JohnS]

Consult kernel drivers and datasheets.

Why do you want to do it?  It's not expected that user code does it.

John

[Cosik]

Hi,

I have radio module which set 0 to pin when it get new unread data. For reduce CPU usage it's necessary to use hardware solutions like GPIO interrupt (EINT).


For some reason it's implemented on hardware

Or maybe you John have a proposal of some other solution for this problem?

[JohnS]

Write a driver.

John

[Stinde]

I did my counter for A13, but the principle should be same for A20. As mentioned before this works only for counter, if you need something else, you have to write a driver.

The /proc/interrupts file contains a list of interrupts and how many times the interrupt has occured.

1. you have to define the GPIO pins in script.bin file. Only EINT pins can used for interrupts Check the A20 EINT pins from the datasheet.

2. set up the GPIO pins writing the GPIO number to /sys/class/gpio/export

3. Set the GPIOs as inputs.  In case of gpio1_pg2, write "in" to /sys/class/gpio/gpio1_pg2/direction

4 Set the interrupt edge. In case of rising edge to gpio_pg2, write "rising" into /sys/class/gpio/gpio1_pg2/edge

5. You should have new interrupt listed in /proc/interrupts file. Write down the interrupt number for the gpio.

6 repeat this for all GPIOs you need and write down the irq numbers.

there is also /proc/irq/ directory. All interrupt numbers have their own subdirectory containing file spurious, which has interrupt count and other info.
First I tried to read the spurious file with my code, but opening the file resets the interrupt counter. Now

I read the /proc/interrupts file line by line and extract the irq count after the irq number.

My code is not fully functional, so I can't publish it yet.

Timo

[Cosik]

Hi,

Ok I found solution which is working good for me.

F

This solution is for Qt

Code Select Expand


QSocketNotifier *keypad_notifier;
QFile keypad_value;
QString gpio_value_path;
gpio_value_path = QString::fromStdString("/sys/class/gpio/gpio63_pi15/value");
keypad_value.setFileName(gpio_value_path);
keypad_value.open(QFile::ReadOnly);
keypad_notifier = new QSocketNotifier(keypad_value.handle(), QSocketNotifier::Exception);
keypad_notifier->setEnabled(true);
connect(keypad_notifier, SIGNAL(activated(int)), this, SLOT(mySlot(int)));

And in slot should be function witch read file, in my case:

Code Select Expand

keypad_value.readAll();