====== Dallas 1-Wire Support ======

  * Support for Dallas 1 Wire is included on Kernel 4.9.34 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 #26 XE.INT16 (GPX2.0)**

<WRAP left round tip 70%>
XU3 / XU4 CON10(30 pin) All GPIO and AIN pins use VDD_IO (1.8V) for the signals. \\
So the level converter is required to connect the sensor.

Hardkernel Shifter-Shield is not working well with multiple 1-wire devices due to a timing issue.\\
So we used Sparkfun [[https://www.sparkfun.com/products/12009|Level converter board]]
</WRAP>
\\
\\
\\

{{:en:1-wire_with_level_converter.png?750|}}
  * **Connection: Level converter**
CON10 Pin 1 (P5V0): Level converter HV \\
CON10 Pin 2 (GND): Level converter GND \\
CON10 Pin 29 (VDD_IO): Level converter LV \\
CON10 Pin 30 (GND): Level converter GND \\
CON10 Pin 26 (XE.INT16): Level converter LV1 \\
Sensor signal : Level converter HV1 \\
{{:en:level_shifter.jpg?nolink|}}

  * **Connection: With External-Supply**
{{:en:1-wire-external-power.png?750|}}

Pin 1 (Left): Ground (-) \\
Pin 2 (Middle): Level converter HV1 \\
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**
{{:en:1-wire-parasite-power.png?750|}}

Pin 1 (Left): Ground (-) \\
Pin 2 (Middle): Level converter HV1 \\
Pin 3 (Right): Ground (-) \\

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

  * Load the required kernel modules: <code>modprobe w1-gpio && modprobe w1-therm</code>
  * Check if your sensor is working: <code>
odroid@odroid:~$ cd /sys/bus/w1/devices/
odroid@odroid:/sys/bus/w1/devices$ ls
10-000802f3be04  w1_bus_master1
odroid@odroid:/sys/bus/w1/devices$
</code>

As you can see my sensor is detected as **10-000802f3be04**, each sensor has a different id. So yours will be different.

  * Read the temperature: <code>
odroid@odroid:/sys/bus/w1/devices$ cd 10-000802f3be04
odroid@odroid:/sys/bus/w1/devices/10-000802f3be04$ cat w1_slave 
37 00 4b 46 ff ff 06 10 da : crc=da YES
37 00 4b 46 ff ff 06 10 da t=27375
odroid@odroid:/sys/bus/w1/devices/10-000802f3be04$
</code>

Temperature is t=27375 or 27.375 degree's Celsius.


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

{{:en:untitled_sketch_bb2.png?750|}}

<code>
odroid@odroid:/sys/bus/w1/devices$ ls
10-000802f384e2  10-000802f3be04  w1_bus_master1
odroid@odroid:/sys/bus/w1/devices$
</code>
Two sensors in parallel.