Converting my incoming data from Software Serial into CHAR

Projects Programming
1

Hello,

I need help regarding my code. I am trying to convert my incoming data that is coming from my Software serial port (Connected with a RS232 connector) into Char. How exactly do I do that? My code is below:

#include <SoftwareSerial.h>

SoftwareSerial mySerial(10, 11); // RX, TX

void setup() {
  // Open serial communications and wait for port to open:
  Serial.begin(9600);
  while (!Serial) {
    ; // wait for serial port to connect. Needed for native USB port only
  }


  Serial.println("Goodnight moon!");

  // set the data rate for the SoftwareSerial port
  mySerial.begin(9600);
  mySerial.println("Hello, world?");
}

void loop() { // run over and over
  if (mySerial.available()) {
    Serial.write(mySerial.read()); //Need to convert this line into CHAR
    Serial.println("Im coming from Arduino");
  }
  if (Serial.available()) {
    mySerial.write(Serial.read());
  }
}
2

you mean you want to cast it to a char?

Serial.write((char)mySerial.read());

3

The examples in Serial Input Basics assume the incoming data is chars

...R

4 
int SoftwareSerial::read()
{
  if (!isListening())
    return -1;

  // Empty buffer?
  if (_receive_buffer_head == _receive_buffer_tail)
    return -1;

  // Read from "head"
  uint8_t d = _receive_buffer[_receive_buffer_head]; // grab next byte
  _receive_buffer_head = (_receive_buffer_head + 1) % _SS_MAX_RX_BUFF;
  return d;
}

From softwareserial.c - it returns an integer, not a char!
Why, I'm not sure - it strikes me as wrong, frankly.

5

From softwareserial.c - it returns an integer, not a char!
Why, I'm not sure - it strikes me as wrong, frankly.

Well, you are wrong, then.

The byte that is read from the serial buffer could be ANY value in the range 0 to 255. That leaves NOTHING to indicate that there was nothing to read. Hence, the function needs to return a multi-byte value so that there is a way to return an error condition.

OP: If you ALWAYS call read only after available() returns a positive value, you can assign the return value to a char variable. The high order byte will be discarded, but that's OK because it will be 0 if the low order byte contains valid data.

If you don't always call available() first (or assume that available() returning 1 means you can read 12 bytes), then you shouldn't assign the return code to a char until after you check that the return value is not -1.