vertx-esp8266

For a complete view : with UML sequence diagrams The purpose is to have a framework for small embedded devices that have the ease of integration and development.

This framework is based on the ideas that also live in Vertx and Node.js.

Features :

1. Loosely coupled and autonomous objects . They have no interface towards each other except a common eventbus, they are not aware of their existence. The wiring of events is done outside.
2. Events have a string signature which is send as a hash for fast correlation between publisher and subscriber. Example :"mqtt/connected" is send to help the programmer remember what he send and received, at compile time only a 16bit int is sued.
3. An eventbus to send message between different objects
4. Eventbus addressing is based on addresses formulated as strings, internally these are converted to unique id's ( 16 bit ) which are more performant to do the routing.
5. Use of lambda's to specify event handlers , keeps the code of event handling easily centralized in the code.
6. Verticles / Objects are eventLoop tasks ( VerticleCoRoutine ) or independent FreeRtos tasks ( VerticleTask ). Attention need to be paid when handlers are async invoked between Freertos tasks. Concurrency can be an issue. So the eventhandler of the task is mostly limited to provide a signal to itself.
7. Serialization of messages on the Eventbus are based on CBOR binary serialization which proves to be efficient
8. .The framework comes with a list of predefined Objects / Actors :

-- Wifi : to signal connection setup and disconnection -- Mqtt : assure publishing of events to mqtt server and maintain connection -- Config : assures store of persistent config items -- Telnet : CLI interface for chaning config -- Monitor : reports task state to logger -- Hardware : abstraction interface for peripherals -- DWM1000_Anchor -- DWM1000_Tag

Hardware

https://docs.google.com/document/d/1fxgZ6O5Crq3wHmV1OV_fEfGh67ktuzFFL1c-V1uz-TM/pub

It uses both led's on a nodemcu esp8266

• led 1 : slow blinking : wifi connected, fast blinking : no connection
• led 2 : slow blinking : mqtt connected, fast blinking : no connection

Configuration via telnet

You can open a telnet session towards the esp8266 once it's on the wifi network. the compilation picks up some environment variables to load the first Wifi AP. The below example as already configured the system.host property to "anchor3", so it's visible via mDNS under "anchor3.local". The property dwm1000.role is used to determine it's role as anchor or tag.

    $ telnet anchor3.local
    Trying 192.168.0.102...
    Connected to anchor3.local.
    Escape character is '^]'.
    anchor3 $ config show
    {
    "system": {
    "host": "anchor3"
    },
      "dwm1000": {
        "x": 1000,
        "y": 2000,
        "role": "A"
      },
      "telnet": {
        "port": 23
      },
      "wifi": {
        "ssid": "YourSSID",
        "pswd": "YourPassword"
      }
    }
    anchor3 $ config set service option abcdef
     done - service option=abcdef 
    anchor3 $ config show
    {
      "system": {
        "host": "anchor3"
      },
      "dwm1000": {
        "x": 1000,
        "y": 2000,
        "role": "A"
      },
      "telnet": {
        "port": 23
      },
      "wifi": {
        "ssid": "YourSSID",
        "pswd": "YourPassword"
      },
      "service": {
        "option": "abcdef"
      }
    }
    anchor3 $ config save
     config saved.
    anchor3 $ <ctrl-D><enter> closes the connection
    Connection closed by foreign host.

Sequence diagram of LPS trilateration

The basics : https://en.wikipedia.org/wiki/Trilateration

sequenceDiagram
participant Tag
participant Anchor1
participant Anchor2
Anchor1 ->> Tag: Blink Message 
Note right of Tag: Anchor1 announces himself to Tag. Tag extracts x,y(Configured static in Anchor ) ,distance ( last measurement )  from blink Message. Tag will include Anchor1 in polling. !! NON-STANDARD blink message

Tag ->> Anchor1: Poll message
activate Tag
Activate Anchor1
Anchor1 ->> Tag: Resp Message ( rx time + fixed delay )
Tag ->> Anchor1: Final message ( poll,resp,final timing included )
Note right of Anchor1 : Anchor1 stores distance for next blink message
deactivate Tag
deactivate Anchor1
Anchor2 ->> Tag: Blink Message 
Note right of Tag: Anchor2 announces himself to Tag. Tag extracts x,y(Configured static in Anchor ) ,distance ( last measurement )  from blink Message. Tag will include Anchor2 in polling.
Activate Tag
Note right of Tag : Tag has the x,y,distance for each Anchor, so can calculate through trilateration the position of itself.Piece of cake (NOT!).  Any Anchors timed out will be removed from polling list
Deactivate Tag

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