Help my graduate project!

Hi guys, can you help me? I've already struggled for serveral moths...
My project is to send the sensor data to app by Bluetooth. My microprocessor is Arduino Uno.
Arduino code is perfect, which can be correctly shown in the serial monitor.
But app inventor does not show any data. I have checked that the Bluetooth is connected, but the data are not transmitted. Who can help me?!!!!!!!!!!!!!!!


These discussions probably can help you

"Perfect" is not enough. To advise you, we need to see in what form you send the data and what the blocks that receive the data look like.

Arduino code is rather long...pls see the below pic.
App inventor aia file looks like below:

Please see the Delimiter article in FAQ

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:

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.

Additionally, in arduino code use BT.print(data); instead of BT.write(data);.

Instead of BT.write(\n); you can use BT.println(data);.

You can insert your entire Arduino code under a triple backtick (the symbol under the tilde (~) near the '1'.

Be sure to show those print() statements for your data values.