1)(2
	 3)(4
	 5)(6
DATA	 7)(8
	 9)(10
	11)(12
	13)(14
	15)(16
	17)(18
	19)(20
	21)(22
	23)(24
	25)(26
	27)(28
	29)(30
	31)(32
	33)(34
	35)(36
	37)(38
	39)(40

- W1-GPIO - One-Wire Interface -
To enable the one-wire interface you need to add the following line to /boot/config
dtoverlay=w1-gpio
or
dtoverlay=w1-gpio,gpiopin=x
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
Newer kernels (4.9.28 and later) allow you to use dynamic overlay loading instead, including creating multiple 1-Wire busses to be used at the same time:

sudo dtoverlay w1-gpio gpiopin=4 pullup=0  # header pin 7
sudo dtoverlay w1-gpio gpiopin=17 pullup=0 # header pin 11
sudo dtoverlay w1-gpio gpiopin=27 pullup=0 # header pin 13
once any of the steps above have been performed, and discovery is complete you can list the devices that your Raspberry Pi has discovered via all 1-Wire busses (by default BCM4), like so:

ls /sys/bus/w1/devices/
n.b. Using w1-gpio on the Raspberry Pi typically needs a 4.7 kΩ pull-up resistor connected between the GPIO pin and a 3.3v supply (e.g. header pin 1 or 17). Other means of connecting 1-Wire devices to the Raspberry Pi are also possible, such as using i2c to 1-Wire bridge chips.