App inventor +arduino

hello Guys,
I want any example of AIA and INO file for sending and receiving data at the same time by bluetoothusing index.
1 . Sending 3 data from app to arduino, the data are numbers
2. Doing mathematical operations with arduino with those numbers
3. Sending those 3 results to app inventor.

I did that, but i get always problems with numbers witch are not shown in their right place in the screen and the error of index too large , despite i changed many times the clock value and delimiter byte.

Thank you for help!!

Search the Tutorials and Guide section for examples

For specific debugging help, post your .ino file and exported .aia file here.

balDERmod1.aia (11.1 KB)

char Incoming_value = 0;
char p ;
int p2 =0;
int palab=0 ;
int b = 0;
void setup() {
// put your setup code here, to run o
pinMode(13, OUTPUT);
void loop() {
// put your main code here, to run repeatedly:
if(Serial.available() > 0)

 palab =Serial.parseInt();

if (palab >0) {b =palab;}
int m = b*2;
Serial.print (millis()/100);
Serial.print ("|");

Serial.print ("25");
Serial.print ("|");

Serial.print (m);
Serial.print ("|");
// Serial.print ("k");



The part of sending from arduino to app is 100% wrong , because i was trying tests

Your message Delimiter (\n) handling on both ends is wrong:

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.

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