@György-Farkas

This actually solved my problem. Thank you very much!

root@o-megaman:~# cat /etc/opkg/distfeeds.conf
#src/gz reboot_core http://downloads.lede-project.org/snapshots/targets/ramips/mt7688/packages
#src/gz reboot_base http://downloads.lede-project.org/snapshots/packages/mipsel_24kc/base
#src/gz reboot_onion http://downloads.lede-project.org/snapshots/packages/mipsel_24kc/onion
## src/gz reboot_luci http://downloads.lede-project.org/snapshots/packages/mipsel_24kc/luci
## src/gz reboot_packages http://downloads.lede-project.org/snapshots/packages/mipsel_24kc/packages
## src/gz reboot_routing http://downloads.lede-project.org/snapshots/packages/mipsel_24kc/routing
## src/gz reboot_telephony http://downloads.lede-project.org/snapshots/packages/mipsel_24kc/telephony
src/gz omega2_core http://repo.onion.io/omega2/packages/core
src/gz omega2_base http://repo.onion.io/omega2/packages/base
src/gz omega2_packages http://repo.onion.io/omega2/packages/packages
src/gz omega2_onion http://repo.onion.io/omega2/packages/onion

root@o-megaman:~# opkg list-installed |grep avr
root@o-megaman:~# opkg list-installed |grep ardu
root@o-megaman:~# 

root@o-megaman:~# opkg install arduino-dock-2
Installing arduino-dock-2 (0.1-1) to root...
Downloading http://repo.onion.io/omega2/packages/onion/arduino-dock-2_0.1-1_mipsel_24kc.ipk
Installing avrdude (6.1-1) to root...
Downloading http://repo.onion.io/omega2/packages/onion/avrdude_6.1-1_mipsel_24kc.ipk
Installing libncurses (6.0-1) to root...
Downloading http://repo.onion.io/omega2/packages/base/libncurses_6.0-1_mipsel_24kc.ipk
Installing libreadline (7.0-1) to root...
Downloading http://repo.onion.io/omega2/packages/base/libreadline_7.0-1_mipsel_24kc.ipk
Installing libusb-compat (0.1.4-2) to root...
Downloading http://repo.onion.io/omega2/packages/base/libusb-compat_0.1.4-2_mipsel_24kc.ipk
Installing libusb-1.0 (1.0.21-1) to root...
Downloading http://repo.onion.io/omega2/packages/base/libusb-1.0_1.0.21-1_mipsel_24kc.ipk
Installing libftdi1 (1.3-1) to root...
Downloading http://repo.onion.io/omega2/packages/packages/libftdi1_1.3-1_mipsel_24kc.ipk
Installing libelf1 (0.168-1) to root...
Downloading http://repo.onion.io/omega2/packages/base/libelf1_0.168-1_mipsel_24kc.ipk
Configuring libusb-1.0.
Configuring libftdi1.
Configuring libelf1.
Configuring libncurses.
Configuring libreadline.
Configuring libusb-compat.
Configuring avrdude.
Configuring arduino-dock-2.

Archiving built core (caching) in: /var/folders/sf/5t0cxvpj3bn0wv48vsrlk8440000gn/T/arduino_cache_494256/core/core_arduino_avr_uno_51f02b7210b938436b779d1c032618e1.a
Sketch uses 444 bytes (1%) of program storage space. Maximum is 32256 bytes.
Global variables use 9 bytes (0%) of dynamic memory, leaving 2039 bytes for local variables. Maximum is 2048 bytes.
> Flashing application '/tmp/sketch.hex' ...

avrdude: AVR device initialized and ready to accept instructions

Reading | ################################################## | 100% 0.00s

avrdude: Device signature = 0x1e950f
avrdude: erasing chip
avrdude: reading input file "0x3f"
avrdude: writing lock (1 bytes):

Writing | ################################################## | 100% 0.00s

avrdude: 1 bytes of lock written
avrdude: verifying lock memory against 0x3f:
avrdude: load data lock data from input file 0x3f:
avrdude: input file 0x3f contains 1 bytes
avrdude: reading on-chip lock data:

Reading | ################################################## | 100% 0.00s

avrdude: verifying ...
avrdude: 1 bytes of lock verified
avrdude: reading input file "0x05"
avrdude: writing efuse (1 bytes):

Writing | ################################################## | 100% 0.00s

avrdude: 1 bytes of efuse written
avrdude: verifying efuse memory against 0x05:
avrdude: load data efuse data from input file 0x05:
avrdude: input file 0x05 contains 1 bytes
avrdude: reading on-chip efuse data:

Reading | ################################################## | 100% 0.00s

avrdude: verifying ...
avrdude: 1 bytes of efuse verified
avrdude: reading input file "0xDA"
avrdude: writing hfuse (1 bytes):

Writing | ################################################## | 100% 0.00s

avrdude: 1 bytes of hfuse written
avrdude: verifying hfuse memory against 0xDA:
avrdude: load data hfuse data from input file 0xDA:
avrdude: input file 0xDA contains 1 bytes
avrdude: reading on-chip hfuse data:

Reading | ################################################## | 100% 0.00s

avrdude: verifying ...
avrdude: 1 bytes of hfuse verified
avrdude: reading input file "0xFF"
avrdude: writing lfuse (1 bytes):

Writing | ################################################## | 100% 0.00s

avrdude: 1 bytes of lfuse written
avrdude: verifying lfuse memory against 0xFF:
avrdude: load data lfuse data from input file 0xFF:
avrdude: input file 0xFF contains 1 bytes
avrdude: reading on-chip lfuse data:

Reading | ################################################## | 100% 0.00s

avrdude: verifying ...
avrdude: 1 bytes of lfuse verified

avrdude done.  Thank you.


avrdude: AVR device initialized and ready to accept instructions

Reading | ################################################## | 100% 0.01s

avrdude: Device signature = 0x1e950f
avrdude: NOTE: "flash" memory has been specified, an erase cycle will be performed
         To disable this feature, specify the -D option.
avrdude: erasing chip
avrdude: reading input file "/tmp/sketch.hex"
avrdude: input file /tmp/sketch.hex auto detected as Intel Hex
avrdude: writing flash (32768 bytes):

Writing | ################################################## | 100% 0.73s

avrdude: 32768 bytes of flash written
avrdude: verifying flash memory against /tmp/sketch.hex:
avrdude: load data flash data from input file /tmp/sketch.hex:
avrdude: input file /tmp/sketch.hex auto detected as Intel Hex
avrdude: input file /tmp/sketch.hex contains 32768 bytes
avrdude: reading on-chip flash data:

Reading | ################################################## | 100% 0.58s

avrdude: verifying ...
avrdude: 32768 bytes of flash verified
avrdude: reading input file "0x0f"
avrdude: writing lock (1 bytes):

Writing | ################################################## | 100% 0.01s

avrdude: 1 bytes of lock written
avrdude: verifying lock memory against 0x0f:
avrdude: load data lock data from input file 0x0f:
> Done, flash successful
> Flash complete!
avrdude: input file 0x0f contains 1 bytes
avrdude: reading on-chip lock data:

Reading | ################################################## | 100% 0.00s

avrdude: verifying ...
avrdude: 1 bytes of lock verified

avrdude done.  Thank you.

I switched to Arduino dock 2 (the one that hosts an extension pins mount) . I also made sure, I have (only) the right opkg package. I can check all the versions and outputs later if that helps.

I have a Onion2+ and used to have the OnionExpansion dock.

Now I switched to the Arduino Dock, set up the Arduino IDE and wanted to flash some basic sketch.

But I get the error:
Can't export GPIO 19, already exported/busy?: Resource busy avrdude done. Thank you.

Could this be because I switched to the Arduino Dock?
I tried echoing 19 to the unexport file but there I got an ash permission error.

@ccs-hello the problem can be reproduced on Omega2+ but I don't have an Omega1 so I am unable to make a statement for Omega1.

@Paul-Austen

I see my mistake, I was getting the packages from the wrong repo (onion instead of onion2). Rookie mistake.
Now everything works - except fo course for both packages 0.5-1 version remains broken.

Thank you very much!

I have put all steps together for future visitors

For onion omega2:

$ wget repo.onion.io/omega2/packages/onion/pyOnionI2C_0.4-1_mipsel_24kc.ipk

$ wget repo.onion.io/omega2/packages/onion/pyOmegaExpansion_0.4-1_mipsel_24kc.ipk

$ opkg list-installed | grep pyO
pyOmegaExpansion - 0.5-1
pyOnionI2C - 0.5-1

$ opkg remove pyOnionI2C pyOmegaExpansion

$ opkg install pyOmegaExpansion_0.4-1_mipsel_24kc.ipk 
Installing pyOmegaExpansion (0.4-1) to root...
Configuring pyOmegaExpansion.

$ opkg install pyOnionI2C_0.4-1_mipsel_24kc.ipk 
Installing pyOnionI2C (0.4-1) to root...
Configuring pyOnionI2C.

$ opkg list-installed | grep pyO
pyOmegaExpansion - 0.4-1
pyOnionI2C - 0.4-1

might duplicate 2436 (https://community.onion.io/topic/2436/onioni2c-import-error)

Same problem here.
I tried downgrading with several methods but unsuccessful.
Package pyOmegaExpansion version 0.4-1 has no valid architecture, ignoring.
@Paul-Austen how did you downgrade if I may ask?

http://repo.onion.io/omega/packages/pyOmegaExpansion_0.4-1_ar71xx.ipk
http://repo.onion.io/omega/packages/pyOnionI2C_0.4-1_ar71xx.ipk

PS: The low version of opkg itself allows for no opkg install package=version notation and if I use --force-downgrade opkg installs 0.5-1 regardless.

These tickets might be related/duplicates:
https://community.onion.io/topic/2438/python-import-error-on-pyonioni2c
https://community.onion.io/topic/2436/onioni2c-import-error