Multi tool use

Sending strings over Serial to Arduino

I'm currently experimenting with sending a string to my Arduino Yun and trying to get it to reply back depending on what I send it.

I picked up a framework of some code here and have been experimenting with it but apart from the serial monitor displaying 'ready' I can't make it go any further.

The code is:

//declace a String to hold what we're inputting
String incomingString;

void setup() {
//initialise Serial communication on 9600 baud
Serial.begin(9600);
while(!Serial);
//delay(4000);
Serial.println("Ready!");
// The incoming String built up one byte at a time.
incomingString = "";
}

void loop () {
// Check if there's incoming serial data.
if (Serial.available() > 0) {
// Read a byte from the serial buffer.
char incomingByte = (char)Serial.read();
incomingString += incomingByte;

// Checks for null termination of the string.
if (incomingByte == '') {
// ...do something with String...
if(incomingString == "hello") {
Serial.println("Hello World!");
}

incomingString = "";
}
}
}


Can anyone point me in the right direction?

Thanks

2 Answers
2

I suspect the problem is that you're adding the null terminator onto the end of your string when you do: incomingString += incomingByte. When you're working with string objects (as opposed to raw char * strings) you don't need to do that. The object will take care of termination on its own.

incomingString += incomingByte

char *

The result is that your if condition is effectively doing this: if ("hello" == "hello") .... Obviously they're not equal, so the condition always fails.

if

if ("hello" == "hello") ...

I believe the solution is just to make sure you don't append the byte if it's null.

incomingString += incomingByte; if (incomingByte == '') {

if (incomeByte) incomingString += incomingByte; else {

Try This:

String IncomingData = "";
String Temp = "";
char = var;

void setup()
{
Serial.begin(9600);
//you dont have to use it but if you want
// if(Serial)
{
Serial.println("Ready");
}
//or
while(!Serial)
{delay(5);}
Serial.println("Ready");
void loop()
{
while(Serial.available())
{
var = Serial.read();
Temp = String(var);
IncomingData+= Temp;
//or
IncomingData.concat(Temp);

// you can try
IncomindData += String(var);
}
Serial.println(IncomingData);
IncomingData = "";
}


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