# OneWire GPIO Binding

This binding reads temperature values from OneWire bus sensors connected to the GPIO bus on Raspberry Pi.

# Supported Things

Temperature sensors. Tested successfully with DS18B20 sensor on Raspberry Pi 3.

# Binding Configuration

The binding requires OneWire sensor to be properly connected to Raspberry Pi GPIO bus, "w1_gpio" and "wire" kernel modules should be loaded. Configuration is proper when /sys/bus/w1/devices folder is present, and contains sensor's data.

# Thing Configuration

The sensors are visible in the system as folders containing files with sensor data. By default all OneWire GPIO devices are stored in /sys/bus/w1/devices/DEVICE_ID_FOLDER, and the temperature value is available in the file "w1_slave". The Thing needs full path to the w1_slave file. Note the values in sysfs are in Celsius.

Optional parameter precision makes it easier to lower precision of the sensor value, i.e. precision 1 makes sensor value to show only one digit after the floating point, precision 2 - shows 2 digits. It makes precision reduction with round up, i.e. 20.534C with precision 1 will be 20.5C, 20.555 with same precision will be 20.6C. Allowed values are from 0 to 3. Default value of parameter is 3(max precision).

In the thing file, this looks e.g. like

Thing onewiregpio:sensor:livingRoom "Living room" [gpio_bus_file="/sys/bus/w1/devices/28-0000061b587b/w1_slave",refresh_time=30,precision=1]

# Channels

The devices supports currently one channel - "temperature" which allows to read temperature from OneWire temperature sensor.

# Full Example

sample onewiregpio.things file content:

Thing onewiregpio:sensor:livingroom "Living room" [gpio_bus_file="/sys/bus/w1/devices/28-0000061b587b/w1_slave",refresh_time=30]

sample onewiregpio.items file content (implements QuantityType for unit conversion):

Number:Temperature LivingRoomTemperature      "Temperature: [%.2f %unit%]" <temperature>  { channel="onewiregpio:sensor:livingroom:temperature" }

sample demo.sitemap file content:

sitemap demo label="Main Menu"
    Text item=LivingRoomTemperature