Pls help me with error 507, Unable to connect. Is the device turned on?

MIT App Inventor Help
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1

Pls help me with error 507. Unable to connect. Is the device turned on?

2

Welcome

Perhaps your issue is here> https://community.appinventor.mit.edu/search?q=error%20507 .

To get specific help advice, describe what you are attempting to connect to in more detail please.

3

Your Clock Timer is nagging your BlueTooth component before it is ready and connected.

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hm-10 module

Problem
Problem978×551 48.2 KB

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OK! I will try to fix it!

6

Can you send me a picture of the blocks?

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when Clock1 Timer
when Clock1 Timer1290×484 69.5 KB

global message
process
process738×130 17 KB

(draggable)

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:

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.

8

Thank you!

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btw. your Clock.Timer event is useless, because once it is comnected it will never be not connected anymore
see also

usually you set your Label to connected or not connected in the BluetoothList.AfterPicking event
the Connect method returns true or false, i.e. connected or not connected

Taifun

Trying to push the limits! Snippets, Tutorials and Extensions from Pura Vida Apps by Taifun.

10

Hello Creator_X

You are using App Inventor's classic bluetooth but your HM-10 module is BLE.

See my website listing popular Bluetooth Modules:
https://www.professorcad.co.uk/appinventortips#TipsBluetooth

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