I want my Arduino to receive an integer through the serial communication. Can you help me with this?
It should be in a form like:
int value = strtoint(Serial.read());
2 Answers
There are several ways to read an integer from Serial, largely depending on how the data is encoded when it is sent. Serial.read() can only be used to read individual bytes so the data that is sent needs to be reconstructed from these bytes.
The following code may work for you. It assumes that serial connection has been configured to 9600 baud, that data is being sent as ASCII text and that each integer is delimited by a newline character (\n):
// 12 is the maximum length of a decimal representation of a 32-bit integer,
// including space for a leading minus sign and terminating null byte
byte intBuffer[12];
String intData = "";
int delimiter = (int) '\n';
void setup() {
Serial.begin(9600);
}
void loop() {
while (Serial.available()) {
int ch = Serial.read();
if (ch == -1) {
// Handle error
}
else if (ch == delimiter) {
break;
}
else {
intData += (char) ch;
}
}
// Copy read data into a char array for use by atoi
// Include room for the null terminator
int intLength = intData.length() + 1;
intData.toCharArray(intBuffer, intLength);
// Reinitialize intData for use next time around the loop
intData = "";
// Convert ASCII-encoded integer to an int
int i = atoi(intBuffer);
}
1 Comment
fersarr
I had to change byte intBuffer[12]; to char intBuffer[12]; for it to compile
You may use the Serial.parseInt() function, see here: http://arduino.cc/en/Reference/ParseInt
1 Comment
Charles Clayton
Not sure what the benefits of the above method are, but this worked for me perfectly.
Serial.read()already returns anint...Serial.read()does return anintbut only so that the calling code can distinguish between a successful read and an error. Correct usage treats the return value as abyteafter checking that it doesn't return-1(which indicates an error).