Sending Data from Arduino via Bluetooth


Im having a little problem with sending data (numbers) from arduino to my app. I have made 3 Labels which display voltage, current, and SoC. However the numbers are not staying in the assigned labels, but rather ossiliating through all of them. I have attahced images of my code and the block diagram which I have made. Can someone please explain what the issue is and how I can fix it.


Be sure to use println() at the end of each message to send from the sending device, to signal end of message.

Only use print() in the middle of a message.

Be sure not to println() in the middle of a message, or you will break it into two short messages and mess up the item count after you split the message in AI2.

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:

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.

Here is an updated blocks sample illustrating these ideas ...

BlueTooth_delimiter_sample.aia (3.4 KB) global message

(split at | instead of ,)

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What if I want to make multiple labels, is there a way to extend the "make a list"?

Also how do I add paramters to the procedure?

click on the blue cog:

click on the blue cog:

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Oh ok, thanks.

Hi, I tried this method, however, it is printing all three texts from the arduino into one of the labels rather than splitting the text into all three labels.

Be careful to split the message at the same character (,|...) you use to separate the message parts

(Canned Reply: ABG - Download those blocks and post them here)

Please download and post each of those event block(s)/procedures here ...
P.S. These blocks can be dragged directly into your Blocks Editor workspace.

See Download Block Images for a demo.

These are the blocks I made, how can I chnage it so that each of the labels only show a specific text sent from the arduino?


Post your complete transmitting code.

Could it be that the code that sends your values to Bluetooth does it differently than the code that sends value to a console?

Hi, thanks for the help. I have managed to figure out the issue I was having.

Please describe the solution to help others with the same problem in future
Thank you