Boolean data type signals are not supported by GPIO Controller

[JavierIntermodalicsKion]

Describe the bug

After upgrading my ros2_control version from v 4.37.0 to this commit hash where boolean data types are handle, I noticed that gpio controller is triggering the following error:

[ros2_control_node-2] Exception thrown during reading the state of: GeneralSafetyIn/RunOk
[ros2_control_node-2] Exception thrown during reading the state of: PhysDigitalInputs/TruckOnState
[ros2_control_node-2] Exception thrown during reading the state of: PhysDigitalInputs/LoadFlap

That error comes from here where it didn't consider between different data types:

How do I fixed?

apply_command function

    auto data_type = command_interface.get_data_type();
    bool success;
    if (data_type == hardware_interface::HandleDataType::DOUBLE) {
      success = command_interface.set_value<double>(
        gpio_commands.interface_values[gpio_index].values[command_interface_index]);
    } else if (data_type == hardware_interface::HandleDataType::BOOL) {
      // To be discussed with Jonas
      success = command_interface.set_value<bool>(
        gpio_commands.interface_values[gpio_index].values[command_interface_index]);
    } else {
      RCLCPP_ERROR(
        get_node()->get_logger(), "Unsupported data type for interface %s",
        full_command_interface_name.c_str());
      return;
    }
    (void)success;
  } catch (const std::exception & e) {
    fprintf(
      stderr, "Exception thrown during applying command stage of %s with message: %s \n",
      full_command_interface_name.c_str(), e.what());
  }

apply_command

    auto & command_interface = command_interfaces_map_.at(full_command_interface_name).get();
    auto data_type = command_interface.get_data_type();
    bool success;
    if (data_type == hardware_interface::HandleDataType::DOUBLE) {
      success = command_interface.set_value<double>(
        gpio_commands.interface_values[gpio_index].values[command_interface_index]);
    } else if (data_type == hardware_interface::HandleDataType::BOOL) {
      // To be discussed with Jonas
      success = command_interface.set_value<bool>(
        gpio_commands.interface_values[gpio_index].values[command_interface_index] < 0.5 ? false : true);
    } else {
      RCLCPP_ERROR(
        get_node()->get_logger(), "Unsupported data type for interface %s",
        full_command_interface_name.c_str());
      return;
    }

ros2_control.config.yaml

gpio_controller:
  ros__parameters:
    type: gpio_controllers/GpioCommandController
    gpios:
      - PhysDigitalOutputs
      - GeneralSafetyIn
      - PhysDigitalInputs
      - PushThrResp
    command_interfaces:
      PhysDigitalOutputs:
        - interfaces:
          - TruckOn
    state_interfaces:
      GeneralSafetyIn:
        - interfaces:
          - RunOK
      PhysDigitalInputs:
        - interfaces:
          - TruckOnState
          - LoadFlap
      PushThrResp:
        - interfaces:
          - PushThroughDist

urdf example

<gpio name="GeneralSafetyIn">
      <state_interface name="RunOK" data_type="bool"></state_interface>
</gpio>

Expected behavior
No error thrown when a bool signal arrives

Screenshots
If applicable, add screenshots to help explain your problem.

Environment (please complete the following information):

• OS: 24.04
• Version Jazzy
• Anything that may be unusual about your environment

Additional context
Add any other context about the problem here, especially include any modifications to ros2_control that relate to this issue.

[christophfroehlich]

The conceptional problem here is that the message type is a double. Does it make sense in your application to use a double message type, but boolean interface types? Wouldn't it make sense to use a custom message, with a custom controller? Or maybe we can generalize the gpio message to support at least double+boolean, which is a very common data type for GPIO obviously.

We have the same ongoing discussion about the dynamic_joint_states topic from JointStateBroadcaster, where we haven't concluded yet how to move forward.

[JavierIntermodalicsKion]

Or maybe we can generalize the gpio message to support at least double+boolean, which is a very common data type for GPIO obviously.

I agree with this. Why not just generalize the GPIO controller to be able to support at least the default data_types that ros2_control supports (double and boolean).

[github-actions]

This issue is being labeled as stale because it has been open 45 days with no activity. It will be automatically closed after another 45 days without follow-ups.

[Ishan1923]

Hi @christophfroehlich,

I would like to work on this.

Issue: the ROS messages currently use double, the hardware interface often exposes bool for GPIOs.

Fix: I plan to implement the compatibility layer in the controller to handle this casting automatically:

• Read: Check if interface is bool -> read as bool -> cast to double for the message.
• Write: Read double from message -> cast to bool (>0.5) -> write to bool interface.

This seems like the robust way to prevent the current exceptions while keeping message compatibility. I'll start by adding a test case to reproduce the crash. :)

[christophfroehlich]

@Ishan1923 fine.
Consider the casting method from here

[Ishan1923]

Thanks, @christophfroehlich! I'll check the referenced casting method to ensure my implementation aligns with existing conventions. I am starting work on the reproduction test case now.