Receiving 24 characters using Bluetooth 4.0

[Ahmed_Zaidi]

Hi,
I have been trying to recieve a 24 characters long string from BluetoothLE 4.0 and arduino nano on the app screen. The string's format is as follows: 10.5;11.3;14.5;20.4;12.3. The app screen only shows first 20 characters. These are actually five pressure values printed on the arduino nano's serial monitor.
I know that I can't change the MTU of Bluetooth 4.0. I can only do it by sending the data in packets. Please guide me how to send and receive data in packets? Thanks a lot.
My app blocks, arduino code and reference images are attached.
Ahmed

TestProject.ino (8.9 KB)
Testproject.aia (3.0 MB)

[ABG]

     while (1) {
        // While in this loop, keep Writing the pressure value in the app
   Serial.print("A:");
   Serial.println(SensorA(p1A,p2A,p3A,p4A,p5A,p6A,q1A,q2A),1);  // Write  pressureA value to app
  Serial.print("B:");
  Serial.println(SensorB(p1B,p2B,p3B,p4B,p5B,p6B,q1B,q2B),1);  // Write  pressureB value to app
  Serial.print("C:");
  Serial.println(SensorC(p1C,p2C,p3C,p4C,p5C,p6C,q1C,q2C,q3C),1);  // Write  pressureC value to app
  Serial.print("D:");
  Serial.println(SensorD(p1D,p2D,p3D,p4D,p5D,q1D,q2D),1);  // Write  pressureD value to app
  Serial.print("mean:");
  Serial.println(average(),1);
 
  delay(800);

Testproject (1).aia (3.0 MB)

[Ahmed_Zaidi]

Thanks a lot ABG! I have tried what you advised. Now, the arduino serial monitor and the app screen look as shown in the attached pictures.

[Patryk_F]

What are the maximum pressure values?

[Ahmed_Zaidi]

The maximum pressure is in double digits somewhere around 15 kPa.

[Patryk_F]

Maybe try something like this:

  Serial.print((String(SensorA(p1A,p2A,p3A,p4A,p5A,p6A,q1A,q2A),1)).toFloat()* 10);  // Write  pressureA value to app
  Serial.print("|");
  Serial.print((String(SensorB(p1B,p2B,p3B,p4B,p5B,p6B,q1B,q2B),1)).toFloat()* 10);  // Write  pressureB value to app
  Serial.print("|");
  Serial.print((String(SensorC(p1C,p2C,p3C,p4C,p5C,p6C,q1C,q2C,q3C),1)).toFloat()* 10);  // Write  pressureC value to app
  Serial.print("|");
  Serial.print((String(SensorD(p1D,p2D,p3D,p4D,p5D,q1D,q2D),1)).toFloat()* 10);  // Write  pressureD value to app
  Serial.print("|");
  Serial.println((String(average(),1)).toFloat()* 10);
  delay(800);

The @ABG approach should work too, you haven't shown us the updated aia project and updated arduino code so we can see what could have gone wrong.

[Ahmed_Zaidi]

@Patryk_F

Serial.print((String(SensorA(p1A,p2A,p3A,p4A,p5A,p6A,q1A,q2A),1)).toFloat()* 10);  // Write  pressureA value to app
  Serial.print("|");
  Serial.print((String(SensorB(p1B,p2B,p3B,p4B,p5B,p6B,q1B,q2B),1)).toFloat()* 10);  // Write  pressureB value to app
  Serial.print("|");
  Serial.print((String(SensorC(p1C,p2C,p3C,p4C,p5C,p6C,q1C,q2C,q3C),1)).toFloat()* 10);  // Write  pressureC value to app
  Serial.print("|");
  Serial.print((String(SensorD(p1D,p2D,p3D,p4D,p5D,q1D,q2D),1)).toFloat()* 10);  // Write  pressureD value to app
  Serial.print("|");
  Serial.println((String(average(),1)).toFloat()* 10);
  delay(800);

Thanks a lot Patryk_F. I have tried what you advised. It works, hurrah. I am also trying ABGs approach. This time I don't see any thing on the app screen. Please find attached files.
Testproject_230906.aia (3.0 MB)

TestProject_ABG.ino (8.9 KB)

[Patryk_F]

Try modifying the code in Arduino:

  Serial.println("A:" + String(SensorA(p1A,p2A,p3A,p4A,p5A,p6A,q1A,q2A),1));  // Write  pressureA value to app
  Serial.println("B:" + String(SensorB(p1B,p2B,p3B,p4B,p5B,p6B,q1B,q2B),1));  // Write  pressureB value to app
  Serial.println("C:" + String(SensorC(p1C,p2C,p3C,p4C,p5C,p6C,q1C,q2C,q3C),1));  // Write  pressureC value to app
  Serial.println("D:" + String(SensorD(p1D,p2D,p3D,p4D,p5D,q1D,q2D),1));  // Write  pressureD value to app
  Serial.println("mean:" + String(average(),1));

[Ahmed_Zaidi]

It still doesn't work. Anyhow, we have solution that works perfectly. Thanks a lot!

[ABG]

I have some doubts as to how print and println might work in BLE as opposed to plain old BlueTooth.

I wonder where and when null terminator bytes might be appearing in the AI2 input stream, and what the items in the stringsReceived value look like.

Here is a copy of your project, with logging to a List Picker's Elements list of every item received in a stringsReceived value.

Would you mind running this and showing us the log?

Testproject_230906 (1).aia (3.0 MB)

My hypothesis is that the A: and associated data are being separated out into separate list items.

[Ahmed_Zaidi]

Thank you ABG for your support.
I am using Adafruit Bluefruit LE (Adafruit Bluefruit LE UART Friend - Bluetooth Low Energy (BLE) : ID 2479 : $17.50 : Adafruit Industries, Unique & fun DIY electronics and kits). I have tried to run what you suggested. Please see the attached pictures. The log was very long and still growing. I have just attached 3 photos. I can send you more. BTW, is there a way to download the entire log?

[ABG]

@Ahmed_Zaidi

I can send you more.

Thank you, the screen shots of the log were very informative and surprising.

Notice how each time stamped entry in the log can contain anywhere from 0 to several readings (B:06) separated by line feeds.
The code I supplied wrongly assumed the line feeds would be filtered out and would contribute to breaking items in the stringValues list properly.
Instead, the line feeds were treated no differently than | or comma delimiters (ignored.)

Furthermore, I see item breaks in the middle of numbers and in the middle of readings.

From what I see, this requires a different approach to dealing with the input stream, introducing a global string variable fed at its end from incoming stringValues items by concatenation, and depleted in front by splitting at application delimiters (line feeds.)

Code to follow.

[Ahmed_Zaidi]

I think the line feed (empty line) is due to the delay or processing time in Arduino nano to start printing the sensor values on the serial monitor. I am also trying to somehow reduce this delay.

[ABG]

Here is a revised approach, using a global buffer, untested.

Testproject_230908.aia (3.0 MB)