Phidgets device

Phidgets are hardware interfaces for sensors and physical outputs. score’s optional Phidget protocol discovers hardware through the Phidget22 library and exposes its channels in the Device explorer.

Availability and prerequisites

Compilation and registration require OSSIA_PROTOCOL_PHIDGETS; libossia defaults this option to off and disables it when the Phidgets dependency is missing. The dependency lookup targets Phidget22 headers and libraries, with platform-specific lookup for macOS, Unix and Windows. On non-Apple Unix, libusb is also required. These build paths are not a tested-platform support matrix.

The integration has an include-path mismatch: score’s device implementation includes ossia/network/phidgets/phidgets_protocol.hpp, while its bundled libossia provides that header under ossia/protocols/phidgets/. This mismatch must be resolved for a Phidgets-enabled build to work; enabling the build option alone is insufficient.

For an enabled, compatible build, provide the Phidget22 runtime and any driver or device-access permissions required by your operating system, as well as the appropriate hardware, hub, cabling and power. Check the hardware with the manufacturer’s tools before diagnosing score. Network-attached hardware additionally needs a reachable Phidgets server and working discovery; score does not provide a server configuration panel here.

Adding and opening channels

1. Connect the hardware, then add a device in the Device explorer and choose Phidget, if that protocol is available in your build.
2. Set Name, the only connection setting. It names score’s device root; it is not a hardware serial number or network hostname. The widget initializes it to Phidgets, while the factory’s default device settings use Phidget, so use the name actually shown in your dialog.
3. Confirm the dialog and allow the discovered tree to populate. The backend opens a Phidget manager, handles attach/detach events and enables Phidgets network-server discovery. There is no manual host, port, password, serial-number filter or channel selector in this settings widget.
4. Expand the required channel and send true to its open child before using it. Channels begin closed. Opening waits up to one second for attachment; failure leaves open false and logs a Phidget open error. Send false to close the channel.
5. Use the channel’s own value as a sensor source or, for a digital output, as a writable destination. Configure any exposed channel controls after opening it.

Opening the manager and discovering a channel are not the same as opening that channel. If names appear but values do not update, check open, hardware access and the channel’s actual capabilities first.

Device tree and addresses

The tree follows the hardware’s parent hierarchy. Device labels or names become nodes; hubs have children such as Port.0, and channel names may receive a numeric suffix. Names are sanitized and made unique. Use the addresses discovered on your hardware rather than copying another installation’s path.

For example, under a root you named Phidgets, a channel address has the form Phidgets:/<discovered hardware path>/<channel>. The angle-bracket portions here describe the hierarchy, not literal node names. Its activation control is the same address with /open appended.

Common channel children are:

Attachment creates nodes and detachment removes them, including empty parents. score advertises tree refresh but does not allow manually adding, removing or renaming these hardware nodes or editing their properties. The live namespace is not serialized as an editable device tree. Reconnect rebuilds the backend and its discovered namespace; plan to reopen channels as needed.

Discovery changes are processed from a queue, one command per 200 ms timer tick in the score wrapper. A larger tree can therefore appear progressively. This timer is not a promised sensor sampling rate.

Input and output direction

Direction depends on the channel, not merely on the protocol:

• Sensor and digital-input values flow from hardware into score. The backend installs hardware change callbacks. Sending a value to a sensor does not turn it into a physical output, even though the generic parameter metadata may advertise bidirectional access.
• Digital-output values flow from score to hardware. The implemented output channel takes a Boolean value and calls the Phidget digital-output state setter. Open the channel before sending values, and verify the physical result safely.
• Channel controls flow from score to the library. open, and where present rate and trigger, configure the channel. channel is read-only metadata.

The channel dispatcher implements selected sensor families, including voltage and voltage-ratio inputs, digital input/output, motion sensors and several environmental sensors. It does not instantiate every channel class in the Phidget22 SDK. A device name or hardware identifier appearing in the SDK is not evidence that all of its functions are exposed in score. In particular, do not infer general motor, servo or analog-output control from the existence of this protocol.

Troubleshooting and limits

• No Phidget entry: check the enabled build and dependencies; changing the device name cannot enable a missing protocol.
• Empty or incomplete tree: verify hardware discovery outside score, allow queued attachments to populate, and check whether the channel class has an implementation. Refresh cannot create an unsupported channel.
• Channel cannot open: inspect the logged Phidget error and check attachment, permissions and whether another application is holding the channel.
• A value can be edited but the hardware does not change: distinguish a real digital output or control from an input measurement. UI access metadata alone is insufficient.
• Network hardware is absent: the backend enables automatic server discovery, but this dialog cannot manually configure or authenticate a remote server. Do not assume that every Phidgets network deployment is usable through this integration.

Source references

The score wrapper, settings and factory are in src/plugins/score-plugin-protocols/Protocols/Phidgets/; its build guard and registration are in that plugin’s CMakeLists.txt and score_plugin_protocols.cpp. Discovery, tree construction, activation and channel behavior are defined in bundled libossia’s src/ossia/protocols/phidgets/phidgets_protocol.cpp, phidgets_node.cpp and phidgets_parameter.hpp. Dependency detection is in libossia’s cmake/FindPhidgets.cmake and cmake/deps/phidgets.cmake.

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