Abstract

Interface service to communicate with several arduino or similar microcontroller based on a serial interface

Contents

- Meta
- Global Functions
- _deriveSubscribesFromCommandMap
- _deriveSubscribesFromTopicMap
- lsb
- prepare
- serialMessageToString
- switchMessageToString
- Class SerialDevice
- Parameters
- Methods
- _traceStringSendToSerial
- close
- getSubscriptions
- handleMessage
- on
- run

Meta

| | |
| --- | --- |
| File | index.js |
| Abstract | Interface service to communicate with several arduino or similar microcontroller based on a serial interface |
| Author | Volker Böhm |
| Copyright | Copyright ( c ) 2020 Volker Böhm |
| License | This software is licensed under the GNU LESSER GENERAL PUBLIC LICENSE Version 3 . It is furnished "as is" , without any support , and with no warranty , express or implied , as to its usefulness for any purpose . |

Callback definitions

$3

Callback to publish messages to the mqtt broker

#### Publish Parameters

| Name | Type | Description |
| ---------- | ------------ | ----------------- |
| message | Message | message to publish | |

Global functions

$3

readonly _deriveSubscribesFromCommandMap (commandMap, topicBegin, qos)

Creates a list of subscribes starting with topicBegin and ending with all strings of the commandMap

#### _deriveSubscribesFromCommandMap Parameters

| Name | Type | Description |
| ---------- | ------------ | ----------------- |
| commandMap | Object | map commands to topic end strings | |
| topicBegin | string | begin of the topic | |
| qos | number | quality of service | |

$3

readonly _deriveSubscribesFromTopicMap (topicMap, qos) => {Object.}

Derives subscriptions from a topic list

#### _deriveSubscribesFromTopicMap Parameters

| Name | Type | Description |
| ---------- | ------------ | ----------------- |
| topicMap | Object. | object with topic properties | |
| qos | 0, 1, 2 | quality of service for the subscription | |

#### _deriveSubscribesFromTopicMap returns

| Type | Description |
| ---- | ----------- |
| Object. | object with topic : qos entries |

$3

lsb (value) => {integer}

Returns the number of the least significant bit of an integer

#### lsb Parameters

| Name | Type |
| ---------- | ------------ |
| value | integer | |

#### lsb returns

| Type | Description |
| ---- | ----------- |
| integer | -1 , if no bit set , else the position of the bit set ( starting with bit 0 ) |

$3

prepare (config, serialDevice)

Creates a serial device object , if not already available

#### prepare Parameters

| Name | Type | Attribute | Default | Description |
| ---------- | ------------ | ------------ | ------------ | ----------------- |
| config | Object | | | serial device configuration settings | |
| serialDevice | SerialDevice | optional | null | serial device object | |

$3

serialMessageToString (message) => {string}

Converts a serial message to a byte stream

#### serialMessageToString Parameters

| Name | Type | Description |
| ---------- | ------------ | ----------------- |
| message | SerialMessage | message to convert | |

#### serialMessageToString returns

| Type | Description |
| ---- | ----------- |
| string | string to transmit |

$3

switchMessageToString (message)

Calculates the switching string from a switch message

#### switchMessageToString Parameters

| Name | Type | Description |
| ---------- | ------------ | ----------------- |
| message | SerialMessage | message to convert | |

#### message properties

| Name | Type | Description |
| ---------- | ------------ | ----------------- |
| value | number | value used to identify the switch and the switching value | |

Class SerialDevice

new SerialDevice(options)

Creates a service class to communicate with several arduino over a serial bus

$3

| Name | Type | Description |
| ---------- | ------------ | ----------------- |
| options | Object | configuration options | |

#### options properties

| Name | Type | Attribute | Default | Description |
| ---------- | ------------ | ------------ | ------------ | ----------------- |
| serialPortName | string | | | name of the port to use | |
| baudrate | integer | optional | 57600 | baud rate to be used | |
| qos | 0, 1, 2 | optional | 1 | quality of service to send messages | |
| trace | string | optional | 'messages' | trace level , supported : errors , messages , internal | |
| keepAliveDelayInSeconds | number | optional | 1 | delay between two keep alive messages to serial | |

$3

#### _traceStringSendToSerial

_traceStringSendToSerial (serialString)

Traces a string send to the serial device

##### _traceStringSendToSerial Parameters

| Name | Type | Description |
| ---------- | ------------ | ----------------- |
| serialString | string | string send to serial device | |

#### close

async close ()

Stops the service

#### getSubscriptions

getSubscriptions () => {topic:qos}

Gets the list of required subscriptions for this service

##### getSubscriptions returns

| Type | Description |
| ---- | ----------- |
| topic:qos | list of subscription strings |

#### handleMessage

handleMessage (mqttMessage)

Processes an incoming mqtt message

##### handleMessage Parameters

| Name | Type | Description |
| ---------- | ------------ | ----------------- |
| mqttMessage | Message | mqtt message | |

#### on

on (event, callback)

Sets a callback .

##### on Parameters

| Name | Type | Description |
| ---------- | ------------ | ----------------- |
| event | string | event name ( not case sensitive ) for the callback ( supported : 'publish' ) | |
| callback | Publish | function ( . . . parameter ) | |

##### on throws

| Type | Description |
| ---- | ----------- |
| Error | if the event is not supported |
| Error | if the callback is not 'function' |

#### run

async run ()

Starts the server