Dallas 1-Wire Support

  • Support for Dallas 1 Wire is included on Kernel 3.10.67-52 and upwards. Make sure you are updated.
  • Will cover an example of a temperature sensor well known DS1820 other 1 wire IC's are supported too.

Default GPIO for 1-Wire is Pin #7 (GPIO83)

  • Connection: With External-Supply

Pin 1 (Left): Ground (-)

Pin 2 (Middle): Pin #7 C1

Pin 3 (Right): VCC (3.3V)

You also need to add a resistor from 4.7k to 10k between pin 2.

  • Connection: Supplying the Parasite-Powered

Pin 1 (Left): Ground (-)

Pin 2 (Middle): Pin #7 C1

Pin 3 (Right): Ground (-)

You also need to add a resistor from 4.7k to 10k between pin 2.

  • Load the required kernel modules:
    modprobe w1-gpio && modprobe w1-therm
  • Check if your sensor is working:
    root@odroid:~# cd /sys/bus/w1/devices/
    root@odroid:/sys/bus/w1/devices# ls
    10-000802f41d67  w1_bus_master1
    root@odroid:/sys/bus/w1/devices#

As you can see my sensor is detected as 10-000802f41d67, each sensor has a different id. So yours will be different.

  • Read the temperature:
    root@odroid:/sys/bus/w1/devices# cd 10-000802f41d67
    root@odroid:/sys/bus/w1/devices/10-000802f41d67# cat w1_slave
    33 00 4b 46 ff ff 03 10 30 : crc=30 YES
    33 00 4b 46 ff ff 03 10 30 t=25562
    root@odroid:/sys/bus/w1/devices/10-000802f41d67#

Temperature is t=25562 or 25.562 degree's Celsius.

Multiple sensors can be connected on the same line as the draw below.

root@bigsmall:/sys/bus/w1/devices# ls
10-000802f37119  10-000802f41d67  w1_bus_master1

Two sensors in parallel.

en/c1_hardware_1w.txt · Last modified: 2016/02/11 17:14 by ck.kim
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