Receiving JSON data from esp32

[Chad_Richins]

I am trying to receive JSON data from my esp32 using classic bluetooth. The data comes through and displays the JSON text when I dont have the get value for key blocks used. If I only use the set text block for a text box and assign the variable to that text box it shows all the data I am passing. When I add the get value for key blocks it displays the "not found" text that is used in the key blocks. What is the correct way to parse the JSON data coming in so that it shows correctly?

JSON data being sent
{"densityAirAvg":7233,"degreesF":75.37999725}

[Juan_Antonio]

Notice how the information is sent and received in this example:

Bluetooth HC-06. Arduino. Send. Receive. Send text file. Multitouch. Image

36.- Ultrasound SR04 sends distance to App by Bluetooth. pA0_Bluetooth_Arduino_Ultrasonido.aia (3.0 KB) Arduino Library Ultrasonic.zip: http://kio4.com/appinventor/9A0_Resumen_Bluetooth.htm#ultrasonido [bluetooth_basico37] #include <Ultrasonic.h> Ultrasonic ultrasonic(12,13); // (Trig PIN, Echo PIN) void setup() { Serial.begin(9600); } void loop(){ Serial.println(ultrasonic.Ranging(CM)); delay(500); } [bluetooth_basico38]

[Kevinkun]

esp_Received is a String, not a Dictionary.

[ChrisWard]

Hello Chad

This Tutorial should help:

CSV tables and Dictionaries

Consider the following table: [image] Taken from this thread: Listpicker and Google sheets You may have a table like this in a .csv file as an asset, or exported and downloaded from a Google sheet. Using [lists_from_csv_table], you can convert your .csv file to a list of lists. There are extensions to view tables, or you could import your table into a relational table, for which there are extensions, or you could use a web viewer with JavaScript and HTML. But what if you do not want to use…

[ABG]

Pull in a web component.

It has a Decode JSON to Dictionary block.

P.S. You are asking for exactly 10 bytes of text? That won't cover a full JSON string.

Be sure to use println() at the end of each message to send from the sending device, to signal end of message. Do not rely on timing for this, which is unreliable.

In the AI2 Designer, set the Delimiter attribute of the BlueTooth Client component to 10 to recognize the End of Line character.

Also, return data is not immediately available after sending a request,
you have to start a Clock Timer repeating and watch for its arrival in the Clock Timer event. The repeat rate of the Clock Timer should be faster than the transmission rate in the sending device, to not flood the AI2 buffers.

In your Clock Timer, you should check

  Is the BlueTooth Client still Connected?
  Is Bytes Available > 0?
     IF Bytes Available > 0 THEN
       set message var  to BT.ReceiveText(-1) 

This takes advantage of a special case in the ReceiveText block:

ReceiveText(numberOfBytes)
Receive text from the connected Bluetooth device. If numberOfBytes is less than 0, read until a delimiter byte value is received.

If you are sending multiple data values per message separated by | or comma, have your message split into a local or global variable for inspection before trying to select list items from it. Test if (length of list(split list result) >= expected list length) before doing any select list item operations, to avoid taking a long walk on a short pier. This bulletproofing is necessary in case your sending device sneaks in some commentary messages with the data values.

Some people send temperature and humidity in separate messages with distinctive prefixes like "t:" (for temperature) and "h:" (for humidity).
(That's YAML format.)

The AI2 Charts component can recognize these and graph them. See Bluetooth Client Polling Rate - #12 by ABG

To receive YAML format messages, test if the incoming message contains ':' . If true, split it at ':' into a list variable, and find the prefix in item 1 and the value in item 2.

[Chad_Richins]

Thank you everyone for the pointers. I made some tweaks, and now things are flowing in and displaying as I was hoping. Below are the updates that I made. In the esp32 code its checking for an updated value every 2500ms, and in AI2 its checking every 2000ms. I let it run for about 30 minutes straight, and it did not run into any issues.