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Permission denied: '/dev/piControl0'

Posted: 14 Apr 2020, 21:44
by albertobueno
Hi!

Today I was having problems editing the /boot/conf.txt file to configure my HDMI touchscreen on my RevPi Connect+. Accidentally (due to a problem with nano and swaps) I erase all the contents of the config.txt file. Afterwards, when I tried running my application using revpimodio2, I got the following error:

PermissionError: [Errno 13] Permission denied: '/dev/piControl0'

Also, I receive this error when I try to open piControl0 with python directly using:
f = open("/dev/piControl0","wb+",0)

When I try to open the piCtory webpage the user admin with the password is also not working......
I know that at the end of the config.txt file were some lines from Kunbus.

I took the following lines from my RevPi Core 3 and added them to the config file of my RevPi Connect+:

# Enable /dev/ttyAMA0 on CM3 until devicetree gets fixed by the Foundation
dtparam=uart0=on

# Enable RevPi specific pins for i2c
dtoverlay=i2c1-bcm2708,sda1_pin=44,scl1_pin=45,pin_func=6

# Enable RevPi realtime clock
dtoverlay=i2c-rtc,pcf2127

# Enable RevPi specific pins for spi
dtparam=spi=on
dtoverlay=kunbus

dtoverlay=mmc

After adding these lines everything seems to be working fine.

Could someone please verify it? I remember the lines were a little bit different.

Best regards,

Re: Permission denied: '/dev/piControl0'

Posted: 15 Apr 2020, 09:15
by dirk
Hi, you can restore the factory defaults again. Also you may make a copy of your actual image to save your work.
Have a look at the Tutorial 01 – Creation of an image.

Re: Permission denied: '/dev/piControl0'

Posted: 15 Apr 2020, 16:02
by albertobueno
Thank you Dirk for the fast response.

I have just installed a new stretch image on my connect and the config.txt file in /boot was not added.......

Again, the user/pasword on the RevPi webpage doesn't work so I cannot configure anything on pictory to test the modules.

Any suggestions?

UPDATE: After reinstalling the image several times using Win32DiskImager (without success) I used the program Etcher from balena. I have no idea why, but this time it worked perfectly

Re: Permission denied: '/dev/piControl0'

Posted: 16 Apr 2020, 08:37
by dirk
Hi, don't panic. Have a look here - How to Save and Install a New Image.
You have to login once with pi/raspberry and enter serial, mac, and type of device. Then after a reboot the device is in factory default state.
Concerning the Win32DiskImager problem - this could be caused by third party software i.e. a security suite. Here in the office we also have to do worarounds i.e. restart the write image process, etc. life is hard, take it easy.