Run the test script from Python 3:
python3 i2ctest.py
To run the file with pipenv:
pipenv install
pipenv run python i2ctest.py
To see which i2c lines have connections:
i2cdetect -y 1
To read a single byte from address 0x60 of the i2c bus:
i2cget -y -a 1 0x60
The i2c baud rate has a huge impact on the reliability of transmission. To edit the baud rate, open the config file:
sudo nano /boot/config.txt
The most effective value is
dtparam=i2c_arm=on
dtparam=i2c_arm_baudrate=40000
dtparam=i2s=on
Then reboot:
sudo reboot