sudo raspi-config nonint do_i2c 0
Now load the relevant modules:
sudo modprobe "i2c-bcm2835" sudo modprobe "i2c-dev" sudo modprobe "rtc-ds1307"
and now check if the I2C device file exists using stat /dev/i2c-1:
$ stat /dev/i2c-1 File: /dev/i2c-1 Size: 0 Blocks: 0 IO Block: 4096 character special file Device: 5h/5d Inode: 169 Links: 1 Device type: 59,1 Access: (0660/crw-rw----) Uid: ( 0/ root) Gid: ( 998/ i2c) Access: 2023-03-14 16:23:06.643999999 +0100 Modify: 2023-03-14 16:23:06.643999999 +0100 Change: 2023-03-14 16:23:06.643999999 +0100 Birth: -
If you instead see
ls: cannot access '/dev/i2c-1': No such file or directory
either the driver is not loaded properly or I2C is disabled. Try rebooting the system and repeating the commands above and possibly checking dmesg for any error messages.