HWMON

Prerequisites:

  • A client running ROS2 with the adi_iio package installed.

Note

This example demonstrates interaction with HWMON (Hardware Monitoring) devices. Please note that it is tailored for specific hardware (Dell Precision 5530 2 in 1) and is intended to serve as a reference for understanding how to interact with HWMON devices in general. The example was tested with Ubuntu 22.04 and ROS2 Humble.

Example: dell_precision_5530.py

Usage:

To run the example, execute the following command in your terminal:

ros2 launch hwmon dell_precision_5530.launch.py

When you execute the command, the ROS2 launch system will start the adi_iio node and the dell_precision_5530 node example.

  1. adi_iio_node:

    • Package: adi_iio

    • Executable: adi_iio_node

    • Purpose: Acts as a bridge to the Linux Industrial I/O (IIO) subsystem, enabling communication with connected hardware sensors.

    • Key Parameters:

      • uri: "local:": Configures the node to use the local IIO context, meaning it will interface with IIO devices on the machine running the launch file.

  2. dell_precision_5530_node:

    • Package: hwmon

    • Executable: dell_precision_5530

    • Purpose: Specifically designed to read and publish hardware monitoring (HWMON) data (like CPU temperatures, fan speeds, battery status) from a Dell Precision 5530 laptop. It relies on the adi_iio_node to access these hardware attributes.

    • Key Parameters:

      • loop_rate: 1: Sets the main operational loop frequency.

Service Clients:

The HWMon node uses two ROS 2 service clients on the /adi_iio_node provider:

  • AttrEnableTopic (/adi_iio_node/AttrEnableTopic)

    This service tells the adi_iio_node to begin sampling a given IIO attribute and publishing it on a ROS 2 topic.

  • AttrDisableTopic (/adi_iio_node/AttrDisableTopic)

    This service stops sampling and tears down the ROS 2 topic created earlier.

Topics:

The HWMon node both subscribes to raw IIO‐driven topics and republishes processed values:

Subscriptions (raw data from adi_iio_node):

/BAT0/curr1/input/read
std_msgs/String
└─ Battery current in milliamps (mA).
    Transformed by `update_bat0_current`:
    μA = float(msg.data) * 1000.0

/BAT0/in0/input/read
std_msgs/String
└─ Battery voltage in millivolts (mV).
    Transformed by `update_bat0_voltage`:
    V = float(msg.data) / 1000.0

/coretemp/temp2/input/read … /coretemp/temp5/input/read
std_msgs/String
└─ CPU core temperature sensor readings in millivolts.
    Transformed by `update_coretemp_core*`:
    V = float(msg.data) / 1000.0

/dell_smm/fan1/input/read
std_msgs/String
└─ CPU fan speed in RPM as a string.
    Transformed by `update_cpu_fan`:
    rpm = int(msg.data)

/dell_smm/fan2/input/read
std_msgs/String
└─ GPU fan speed in RPM as a string.
    Transformed by `update_gpu_fan`:
    rpm = int(msg.data)

Publications (processed data):

/BAT0/uA
std_msgs/Float64
└─ Battery current in microamps (after conversion).

/BAT0/V
std_msgs/Float64
└─ Battery voltage in volts (after conversion).

/coretemp/core0 … /coretemp/core3
std_msgs/Float64
└─ Core temperatures expressed as voltages (V).

/fan/cpu
std_msgs/Int32
└─ CPU fan speed in RPM.

/fan/gpu
std_msgs/Int32
└─ GPU fan speed in RPM.