Serial communication problem !

Projects Programming
9

Posted this for somebody else, but it seems applicable here too. Make sure to and read and understand what is happening, rather than just copying the code and hoping it works:

/*

  • Example for Serial2Int
  • When reading from the serial monitor, there are two important things to note:
  • (1) Bytes are read one at a time. So sending "246" will be read by your
  • code as '2', then '4', then '6'. If you want to identify them as related in some
  • way, you need a way to determine that. This example uses start and stop bytes.
  • (2) Sending a number through the monitor sends it's ASCII representation, not
  • the value itself. So typing 3 and hitting enter would send '3' or 51 as per the
  • ascii table. To account for this, we will be using atoi(), which takes a null
  • terminated array of chars, also known as a string, and produces the int equivalent.
    */

// To send a number through the serial monitor, put it between brackets
const char startByte = '<';
const char stopByte = '>';

// Maximum characters in an int + null terminated character
const short maxBuffer = 6;

void setup() {
Serial.begin(57600);
Serial.println("[Serial2Int]");
}

void loop() {
// Stores the characters between the start and stop bytes
static char buffer[maxBuffer];
// Keeps track of spot in buffer
static short index=0;

if (Serial.available() > 0 ) {
char inChar = Serial.read();

if (inChar==startByte) { // If start byte is received
index=0; // then reset buffer and start fresh
} else if (inChar==stopByte) { // If stop byte is received
buffer[index] = '\0'; // then null terminate
processData(buffer); // and process the data
index=0; // this isn't necessary, but helps limit overflow
} else { // otherwise
buffer[index] = inChar; // put the character into our array
index++; // and move to the next key in the array
}

/* Overflow occurs when there are more than 5 characters in between

  • the start and stop bytes. This has to do with having limited space
  • in our array. We chose to limit our array to 5 (+1 for null terminator)
  • because an int will never be above 5 characters */
    if (index>=maxBuffer) {
    index=0;
    Serial.println("Overflow occured, next value is unreliable");
    }
    }
    }

void processData(char buffer[]) {
unsigned int value = atoi(buffer); // convert string to int
Serial.print("Value: ");
Serial.println(value);
}