B4R Code Snippet Data JSON Format to Node-RED

For sending data from Arduino/ESP to Node-RED (running on a Raspberry Pi), JSON format is an option as Node-RED provides simple methods for parsing JSON.

The example sub writes via asyncstream a Key:Value Pair Array as a JSON string.

Notes

• Watch the program storage space when using - the example sub with 2 parameter takes about 5%.
• There might be more efficient ways providing this functionality (like a JSON Library) but did not came across a suitable (simple and easy to parse) library (yet).
• Another option is to use MQTT - but in this case wanted some minimal effort to sent data.

Example

Private astream As AsyncStreams
Private counter1 As Int = 1958
Private counter2 As Double = 19.58
ToJSON(astream, Array As String("counter1", "counter2"), Array As String(counter1, counter2))

Output
{"counter1":1958,"counter2":19.58}

Sub ToJSON(astr As AsyncStreams, k() As String, v() As String)
   astr.Write("{")
   For i = 0 To k.Length - 1
     astream.Write("""")
     astream.Write(k(i).GetBytes)
     astream.Write(""":")
     astream.Write(v(i).GetBytes)
     If i < k.length - 1 Then astream.Write(",")
   Next
   astr.Write("}")
   astr.Write(CRLF)
End Sub

Node-RED
Use a JSON Node, fed from f.e. Serial or UDP, which payload can be taken in f.e. a Function Node.

var counter1 = msg.payload.counter1;
var counter2 = msg.payload.counter2;
node.warn(counter1 + " = " + counter2);