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Sparrow Object Model
The object model allow any IoT device to describe itself via a set of object instances (similar to LWM2M). Any IoT device have one to N instances and the first instance (called instance zero) is used for discovery of the device / product type and for device management.
Each object defines a number of variables. Some are common with all Sparrow objects and others are specific for each object type. Some of the common variables are for discovery and are mandatory.
There are 5 mandatory variables that all object instances must support.
| Variable | ID | Description |
|---|---|---|
| Product/Object Type | 0x000 | the object type (64 bit) - for instance zero it is a product type and for the other instances it is the object type |
| Object Id | 0x001 | the object identifier (128 bit) - for instance zero it is the unique device identifier (128 bit) |
| Object label | 0x002 | a string describing the object |
| Number of sub-instances | 0x003 | for instance zero it is the number of object instances in this IoT device excluding instance zero, which always exists |
| Object subtype | 0x004 | the object subtype (32 bit) |
| Event Array | 0x005 | 64 bit event information that describes if the object instance is armed, trigged, etc. For instance zero, it can be used to enable or disable events from all instances in this IoT device. |
There is a set of variables that are optional but common for all instances. If such a variable exists, it has the same specification regardless of which instance it belongs to. An example of such variable is the Unit Boot Timer (0x0c9) that gives the time since boot of the device.
The variables starting at 0x100 are specific for the object they are in - such as these from the LEDs instance:
| Variable | ID | Description |
|---|---|---|
| Number of LEDs | 0x100 | gets the number of LEDs that can be controlled via this object instance |
| LED control | 0x101 | control the state of the LEDs |
| LED set | 0x102 | set the specific LED to on |
| LED clear | 0x103 | set the specific LED to off |
A Sparrow IoT device have at least one instance - the instance zero. Using the Sparrow protocol (Encap and TLV) it is possible to discover what type of device it is and which object instances it implements. The Zolertia Re-mote example device have the following instances:
- Instance Zero with product type:
70b3d57d53000001. - Instance 1 with object type:
0090da0303010010 Flash instance(primary image) - Instance 2 with object type:
0090da0303010010 Flash instance(secondary image) - Instance 3 with object type:
0090da030201001e LEDs instance(control of the RGB LED) - Instance 4 with object type:
0090da030201001d Button instance(the user button of Re-Mote) - Instance 5 with object type:
0090da0303010023 Network statistics(data about the RPL network)
Running the discovery tool on it will show the following output:
> ./tlvdiscovery.py fd00::212:4b00:615:9abf
HOST: fd00::212:4b00:615:9abf
Product label: Zoul RE-Mote type: 70b3d57d53000001 instances: 5
Booted at: 2016-06-14 19:57:56 - 4 sec 778 msec
Instance 1: type: 0090da0303010010 Primary firmware
Instance 2: type: 0090da0303010010 Backup firmware
Instance 3: type: 0090da030201001e LEDs
leds are set to 0x00 (3 user leds)
Instance 4: type: 0090da030201001d Button
button is pressed, has been pressed 0 times
Instance 5: type: 0090da0303010023 Network Statistics
Version: 0 Capabilities: 0x700 ROUTER PUSH
This shows the name of the device and its type. The number of instances (5) and then all the instances and the object types of them in this device.
Sparrow makes use of EUI-64 ID for all the object types and also image types. This means that
anyone that owns a OUI ID range can create their own non-overlapping object IDs.
SICS have a ID range defined 70-B3-D5-70-5 and using this EUI-64 can be defined like:
70-B3-D5-70-5X-<24-bit ID>
Where the 24-bit ID is defining the type of the object and the prefix ensures that it is globally unique so that there is no need for having a registry for objects. The whole 64-bit identifier is read out in the discovery to identify which object it is that any given instance implements.
- Image type - for firmware images to ensure that only correct image types are uploaded to a specific device
- Object type - any functional object such as temperature sensor object, lamp object, etc.
- Product type - any type of product such as a Zolertia Re-mote or Yanzi LED Lamp
The ID's starting with 0090da are Yanzi Networks IDs with their own schema for the different types.