Plotting live sensor data using BME280 and HC-05 module

Dear AI2-Fellows,

I built a little AI2-App with following Specs:

  • HC05 Bluetooth Module
  • Bosch BME280 humidity, pressure, temperature sensor hooked up to an Arduino Uno
  • Life data is displayed in one screen

My problems are:
Even though I can receive the data sometimes correctly in the 4 sensor fields, it often throws an error in the app as follows:
Select list item: List index too large
Select list item: Attempt to get item number 2 of a list of length 1: (447)
or attempt to get item number 4 of list length 4.

The list should always have the same length of 4. Please have a look at my blocks below:

As a separator, I am using forward slash.

Thank you!

Please see the Delimiter article in FAQ

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

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 Arduino, 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 Arduino sneaks in some commentary messages with the data values.

P.S. The right click menu on a block lets you download live blocks that can be dragged into the Block Editor and corrected.
Shame you didn't do that, now you have to retype.