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One Wire Temperature

License: MIT

ROS node for reading temperatures from different sensors and publishes them as sensor_msgs/Temperature messages. It is designed to work with DS18B20 1-wire temperature sensors, but also reads a Raspberry Pi's CPU temperature sensor if running on a Pi.

Params

<node name="temperature_node" pkg="temperature_node" type="temperature_node.py" output="screen">

  <!-- 
  Comma-separated list of names for 1-wire sensors
  Example: "motor_left, motor_right"
  -->
	<param name="onewire_names" value=""/> 

  <!--
  Comma-separated list of addresses for 1-wire sensors
  Example "28-9809be0164ff, 28-a99dbd0164ff"
  -->
	<param name="onewire_addresses" value=""/> 

	<!-- Update rate in Hz -->
	<param name="rate" value="0.7"/>

</node>

Published Topics

For each 1-wire sensor, this node will publish a sensor_msgs/Temperature message on a topic with the name temp/<sensor_name>, where <sensor_name> is replaced with the name of the sensor from the list.

  • /temp/cpu (sensor_msgs/Temperature): The temperature of the Raspberry Pi's CPU.

  • /temp/<sensor_name> (sensor_msgs/Temperature): The temperature of the 1-wire sensor with the given name. There will be one of these topics for each 1-wire sensor.

Note: The sensor_msgs/Temperature message includes fields for the temperature in Celsius and the variance. The variance field is currently not used and is set to 0.0 in all published messages. The header field is also not populated. Depending on your application, you might want to modify the node to populate these fields.

Finding DS18B20 Addresses

The addresses specified as the params are the unique hardware addresses of the sensors. If you are using a Raspberry Pi and have connected 1-wire sensors to it (the 1-wire interface must be enabled in the /boot/config.txt), you can find these addresses by accessing the 1-wire device files in the /sys/bus/w1/devices/ directory. Each subdirectory's name should be the address of a connected sensor. A simple way of figuring out which one is which is to heat one of the sensors and observe which address value changes in temperature.