W1-GPIO - One-Wire Interface
To enable the one-wire interface you need to add the following line to /boot/config.txt, before rebooting your Pi:
if you would like to use a custom pin (default is BCM4, as illustrated in pinout herein).
Alternatively you can enable the one-wire interface on demand using raspi-config, or the following:
sudo modprobe w1-gpio
once either of the steps above has been performed, you can list the devices your Raspberry Pi can probe via (by default) BCM4, like so: