serialEvent problem

Using Arduino Programming Questions
#1

Hi,

I am sending three bytes of data through Android phone to Arduino via Bluetooth module.

When I am using code belove, everything works fine, without a single problem.

void serialEvent()
{

  byte buffer_rx [3];
  byte i = 0;
  
  byte deltaON_rx;
  byte deltaOFF_rx;
  
  while (Serial.available())
  {
    byte inByte = Serial.read();

    if (inByte == 0xFE)
    {     
      deltaON_rx = buffer_rx[0];
      deltaOFF_rx = buffer_rx[1];
      test_rx = buffer_rx[2];
       
      i = 0;
    }
    else
    {
      if (i < 3)
      {   
        buffer_rx [i] = inByte;
        i++;
      }
    }
    
    // EEPROM deltaON
    if (deltaON_rx != EEPROM.read(0)
    {
      EEPROM.write(0, deltaON_rx);
    }
    
    // EEPROM deltaOFF
    if (deltaOFF_rx != EEPROM.read(1)
    {
      EEPROM.write(1, deltaOFF_rx);
    }
  }
}

Now I want to add some kind of a security in case that some strange number would occur. Since I know what numbers to expect (from 3 to 15 for deltaON and from 1 to 13 for deltaOFF), I added just two simple condition before writing to EEPROM

    // EEPROM deltaON
    if ((deltaON_rx != EEPROM.read(0)) && (deltaON_rx >= 3) && (deltaON_rx <= 15)) 
    {
      EEPROM.write(0, deltaON_rx);
    }
    
    // EEPROM deltaOFF
    if ((deltaOFF_rx != EEPROM.read(1)) && (deltaOFF_rx >= 1) && (deltaOFF_rx <= 13)) 
    {
      EEPROM.write(1, deltaOFF_rx);
    }

But, it doesn’t work. Most of the time I get some random (wrong) numbers, when I send new values from Android app (usually 10 and 7), no matter what kind of numbers I send (in range from 3 to 15 for deltaON and 1 to 13 for deltaOFF).

I don’t understand what could be wrong, because if I remove this two conditions, everything works fine (tested many times).

Any idea is much appreciated :slight_smile:

#2

Why don't you send the values received to the serial monitor to debug?

#3

What happens in serialEvent if there's only one character to read?

#4

Keep in mind that all serialEvent() does is save you the trouble of writing (as the last thing in loop() )

if (Serial.available() > 0) {
   mySerialFunction();
}

I would receive all of the data before analyisng any of it. One of the examples is serial input basics should be suitable.

...R

#5

Robin2: Keep in mind that all serialEvent() does is save you the trouble of writing (as the last thing in loop() )

I was able to fix the problem. I renamed and changed function serialEvent so now I am calling function "getPacket()" from main loop.

  if (Serial.available() > 0) 
  {
    getPacket();
  }

Also, I changed variables in function for buffer and counter from local to global. Now it works as it should.

Again, thank you guys for all the advices! :D

#6

luxy: Also, I changed variables in function for buffer and counter from local to global. Now it works as it should.

Changing them from local to static would also have worked.

#7

Changing them from local to static would also have worked.

You mean, of course, keeping them local, but adding the static qualifier, would also have worked.

#8