Temperature sensors

Wiring:

• Waterproof:
  • Red: 3.3V
  • Yellow: 4.7 k pull-up (5.1k fine) and gpio pin nominated in /boot/config.txt
  • Black: ground
• Kit module:
  • 1 (labelled -): ground
  • 2: 3.3V
  • 3 (labelled S): 4.7k pull-up and signal

Wire as many as you like in parallel. There are limits to numbers and to wiring length, but they're not simple.

At the end of /boot/config.txt (replace 21 with pin number):

dtoverlay=w1-gpio,gpiopin=21

Save and reboot.

ls -l /sys/bus/w1/devices

Grab its address (format 28-xxxxxxxxxxx). Read the temperature with

cat /sys/bus/w1/devices/28-[address]/w1_slave

The numerical value after t= is the temperature in thousandths of a degree C.