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IO Connector Plugin

Version: 1.0

Status: ⚫⚫⚫

IOConnector plugin for Thunder framework.

Table of Contents

Introduction

Scope

This document describes purpose and functionality of the IOConnector plugin. It includes detailed specification about its configuration, properties provided and notifications sent.

Case Sensitivity

All identifiers of the interfaces described in this document are case-sensitive. Thus, unless stated otherwise, all keywords, entities, properties, relations and actions should be treated as such.

Acronyms, Abbreviations and Terms

The table below provides and overview of acronyms used in this document and their definitions.

Acronym Description
API Application Programming Interface
GPIO General-Purpose Input/Output
HTTP Hypertext Transfer Protocol
JSON JavaScript Object Notation; a data interchange format
JSON-RPC A remote procedure call protocol encoded in JSON

The table below provides and overview of terms and abbreviations used in this document and their definitions.

Term Description
callsign The name given to an instance of a plugin. One plugin can be instantiated multiple times, but each instance the instance name, callsign, must be unique.

References

Ref ID Description
HTTP HTTP specification
JSON-RPC JSON-RPC 2.0 specification
JSON JSON specification
Thunder Thunder API Reference

Description

The IO Connector plugin provides access to GPIO pins.

The plugin is designed to be loaded and executed within the Thunder framework. For more information about the framework refer to [Thunder].

Configuration

The table below lists configuration options of the plugin.

Name Type M/O Description
callsign string mandatory Plugin instance name (default: IOConnector)
classname string mandatory Class name: IOConnector
locator string mandatory Library name: libWPEIOConnector.so
startmode string mandatory Determines in which state the plugin should be moved to at startup of the framework
pins array mandatory List of GPIO pins available on the system
pins[#] object mandatory Pin properties
pins[#].id integer mandatory Pin ID
pins[#].mode string mandatory Pin mode (must be one of the following: Active, Both, High, Inactive, Low, Output)
pins[#]?.activelow boolean optional Denotes if pin is active in low state (default: false)

Interfaces

This plugin implements the following interfaces:

Properties

The following properties are provided by the IOConnector plugin:

IOConnector interface properties:

Property R/W Description
pin read/write GPIO pin value

pin property

Provides access to the GPIO pin value.

Also see: activity

The pin id parameter shall be passed as the index to the property, i.e. pin@<pin-id>.

Index

Name Type M/O Description
pin-id string mandatory ...

Value

Name Type M/O Description
(property) integer mandatory Value of the pin
Name Type M/O Description
(property) integer mandatory Value of the pin

Errors

Message Description
ERROR_UNKNOWN_KEY Unknown pin ID given

Example

Get Request

{
  "jsonrpc": "2.0",
  "id": 42,
  "method": "IOConnector.1.pin@189"
}

Get Response

{
  "jsonrpc": "2.0",
  "id": 42,
  "result": 1
}

Set Request

{
  "jsonrpc": "2.0",
  "id": 42,
  "method": "IOConnector.1.pin@189",
  "params": 1
}

Set Response

{
    "jsonrpc": "2.0",
    "id": 42,
    "result": "null"
}

Notifications

Notifications are autonomous events triggered by the internals of the implementation and broadcasted via JSON-RPC to all registered observers. Refer to [Thunder] for information on how to register for a notification.

The following events are provided by the IOConnector plugin:

IOConnector interface events:

Notification Description
activity Notifies about GPIO pin activity

activity notification

Notifies about GPIO pin activity.

Description

Register to this event to be notified about pin value changes

Parameters

The pin ID parameter shall be passed within the id parameter to the register call, i.e. <pin id>.<client-id>.

Notification Parameters

Name Type M/O Description
params object mandatory ...
params.value integer mandatory Value of the pin

Example

Registration

{
  "jsonrpc": "2.0",
  "id": 42,
  "method": "IOConnector.1.register",
  "params": {
    "event": "activity",
    "id": "189.myid"
  }
}

Notification

{
  "jsonrpc": "2.0",
  "method": "189.myid.activity",
  "params": {
    "value": 1
  }
}

The client ID parameter is passed within the notification designator, i.e. <pin id>.<client-id>.activity.

The pin ID parameter is passed within the notification designator, i.e. <pin id>.<client-id>.activity.