I2C service not running ...Work Around

[aitonos]

FInally , after many trials and errors with Chat GPT ( Tried Perplexity and found it useless at least for this issue), this is a resume of steps taken, I hope they are valid to others  as I can't replicate by myself all the things we ( GPT and me) did with success until get the service working again.

None of the solutions in this thread worked for me; I also have Maiana running and it was a fresh install, so no idea why this happens; what it's true is that now works and survives restarts:

What we did + copy/paste steps:

Context: 

On RPi5/OpenPlotter, openplotter-i2c-read.service was failing because Adafruit Blinka was importing "lgpio" , but the system only had the compiled "_lgpio" module. We installed the proper lgpio Python wrapper (with the API Blinka expects) and then adjusted the systemd service to run in a writable runtime directory so lgpioncan create its notify files. After that, the service stayed running and survived reboot.

0) Check the error (optional)

Code:

sudo systemctl status openplotter-i2c-read.service --no-pager -l
journalctl -u openplotter-i2c-read.service -n 80 --no-pager

1) Confirm what’s installed (you’ll usually see only _lgpio )

Code:

python3 -c "import pkgutil; print([m.name for m in pkgutil.iter_modules() if 'lgpio' in m.name])"
python3 -c "import _lgpio; print(_lgpio.__file__)"

2) Install the PyPI  lgpio wrapper system-wide (this is the key step) This forces installing the wrapper into /usr/local/... even if Debian says “already installed”.

Code:

sudo apt install -y python3-pip
sudo python3 -m pip install --break-system-packages --upgrade --ignore-installed lgpio

3) Verify 

Code:

lgpio

imports and exposes the API Blinka needs
Run from a writable directory (important):

Code:

cd /tmp
python3 -c "import lgpio; print(lgpio.__file__); print('gpiochip_open?', hasattr(lgpio,'gpiochip_open'))"

Expected:

Code:

gpiochip_open? True

4) Fix systemd service working directory (so lgpio can create its notify files) 

Edit the service:

Code:

sudo nano /etc/systemd/system/openplotter-i2c-read.service

Use this [Service] block (adjust only if your system differs):

Code:

[Service]

Environment=OPrescue=0
WorkingDirectory=/run/openplotter-i2c
RuntimeDirectory=openplotter-i2c
RuntimeDirectoryMode=0700
EnvironmentFile=/boot/firmware/config.txt
ExecStart=/usr/bin/openplotter-i2c-read $OPrescue
User=pi
Restart=always
RestartSec=3

Reload + restart:

Code:

sudo systemctl daemon-reload
sudo systemctl restart openplotter-i2c-read.service

5) Confirm it’s stable (and survives reboot)

Code:

sudo systemctl status openplotter-i2c-read.service --no-pager -l
systemctl show -p NRestarts --value openplotter-i2c-read.service

Expected: Active: active (running)
and NRestarts=0

Reboot test:

Code:

sudo reboot

After reboot:

Code:

sudo systemctl status openplotter-i2c-read.service --no-pager -l

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Hope it helps someone... (desperate as I was) 

Have a good weekend!