gpio error

[mrdebug]

I suggest you to use pigpio or wiringpi library in order to manage raspberry pi gpios.

[tinashe]

Thanks mrdebug
but i do not think it will work because i tried the following
code since /dev/gpiomem does not need root permission
int fd = open("/dev/gpiomem", O_RDONLY) ;

if (fd == -1) {

   qDebug()<<"Unable to open /dev/gpiomem";
  exit(1);

}
else{

  qDebug()<< "gpio /dev/gpiomem";

}
and still unable to access the file

[SGaist]

Hi,

Since you are using Emeria.os, you should ask their folks on whether these GPIO's are accessible and if so, how.

[tinashe]

This post is deleted!

[tinashe]

@SGaist
thank you for the reply
Sorry its Emteria.os
i was told to
the gpios are accessable
Make sure those files are accessible from your application. Check Linux file permissions. and how do i check for these permissions?

[jsulm]

@tinashe said in gpio error:

and how do i check for these permissions?

ls -lh /sys/class/gpio/unexport

You should read about UNIX/Linux basics.
To get access for the group your user is in:

chmod g+rw /sys/class/gpio/unexport

For user

chmod u+rw /sys/class/gpio/unexport

[tinashe]

@jsulm
thank you very much
how do i run this in my main file or c++ file because i have seen these commands run in cmd terminal.

[jsulm]

@tinashe said in gpio error:

how do i run this in my main file or c++ file because i have seen these commands run in cmd terminal

Why do you want to do it in your app? Just do it once in a terminal...
The commands I provided to set access rights need root access (via sudo for example):

sudo chmod g+rw /sys/class/gpio/unexport

So, your app will not be able to do this.
But you should really check how access rights are handled in Emteria.os

[tinashe]

@jsulm said in gpio error:

For user
unfortunately i can not do it on the terminal.
or can i do this in the cmd.txt found in boot folder?

[tinashe]

@jsulm
unfortunately the ssh server is locked for demo which am using currently

[jsulm]

@tinashe See "man 2 chmod".
But most probably your user will need to start the app as root (sudo for example).

[tinashe]

@tinashe

i was told to do permission seeting in /data/init.d

[tinashe]

@jsulm
chmod g+rw /sys/class/gpio/unexport
cd /etc/udev/rules.d/
touch local.rules
ACTION=="add", KERNEL=="gpio", MODE="0666"
and did notwork

[jsulm]

@tinashe This does not have anything to do with Qt now, please find out how to do this with Linux.

[tinashe]

@jsulm
thank you very much will do that