Using SoftwareSerial as a private member variable - arduino

Question

I'm trying to convert Sparkfun's example code for the SM130 RFID Reader into a class/library that's encapsulated nicely and can be used in multiple arduino sketches.
Sparkfun Example Code: https://github.com/sparkfun/RFID_Evaluation_Shield/blob/master/Firmware/RFID_Eval_13_56MHz.ino
Most of it went pretty smoothly, until I tried to make the Software Serial communications a member variable -- I keep getting errors like:
/Users/scottnla/Dropbox/arduino/libraries/SM130/SM130.cpp: In constructor 'SM130::SM130()':
/Users/scottnla/Dropbox/arduino/libraries/SM130/SM130.cpp:8: error: no matching function for call to 'SoftwareSerial::SoftwareSerial()'
/Applications/Arduino.app/Contents/Resources/Java/libraries/SoftwareSerial/SoftwareSerial.h:83: note: candidates are: SoftwareSerial::SoftwareSerial(uint8_t, uint8_t, bool)
/Applications/Arduino.app/Contents/Resources/Java/libraries/SoftwareSerial/SoftwareSerial.h:48: note: SoftwareSerial::SoftwareSerial(const SoftwareSerial&)
I found a stackoverflow post that seems to address this issue (Creating a Library for an Arduino), but their solution doesn't seem to work for me. The IDE's error messages seem to indicate that I can only use a 'base initializer' in a constructor; but this isn't what I want. What's the best way to deal with the problem that I'm having in my code?
Thanks!
Code below:
SM130.h
#ifndef SM130_h
#define SM130_h
#include<Arduino.h>
#include <WConstants.h>
class SM130 {
public:
SM130();
void connect(int RX, int TX);
void check_for_notag();
void halt_tag();
void parse_tag();
void print_serial();
void seek_tag();
void set_flag();
private:
int rfid_flag;
int data[11];
SoftwareSerial rfid;
};
#endif
SM130.cpp
#include <WProgram.h>
#include <SoftwareSerial.h>
#include "SM130.h"
SM130::SM130() {
rfid_flag = 0;
}
void SM130::connect(int RX, int TX) : rfid(RX, TX) {
if(!Serial.available()) {
Serial.begin(9600);
}
Serial.println("Connecting to SM130 RFID Reader...");
//rfid = SoftwareSerial(RX, TX);
rfid.begin(19200);
if(rfid.available()) {
rfid.println("Connected to SM130 RFID Reader!");
}
delay(10);
}
void SM130::check_for_notag() {
seek_tag();
delay(10);
parse_tag();
set_flag();
if(rfid_flag == 1) {
seek_tag();
delay(10);
parse_tag();
}
}
void SM130::halt_tag() {
rfid.write(0xFF);
rfid.write((byte)0x00); //manual typecasting needed for 0x00 to differentiate it from null pointer -- silly c compilers!
rfid.write(0x01);
rfid.write(0x93);
rfid.write(0x94);
}
void SM130::parse_tag() {
while(rfid.available()) {
if(rfid.read() == 0xFF) {
for(int i = 1; i < 11; i++) {
data[i] = rfid.read();
}
}
}
}
void SM130::print_serial() {
if(rfid_flag == 1) {
Serial.print(data[5],HEX);
Serial.print(data[6],HEX);
Serial.print(data[7],HEX);
Serial.print(data[8],HEX);
Serial.println();
}
}
void SM130::seek_tag() {
//insert hex tags here
rfid.write(0xFF);
rfid.write((byte)0x00); //manual typecasting needed for 0x00 to differentiate it from null pointer -- silly c compilers!
rfid.write(0x01);
rfid.write(0x82);
rfid.write(0x83);
}
void SM130::set_flag() {
if(data[2] == 6) {
rfid_flag++;
}
if(data[2] == 2) {
rfid_flag = 0;
}
}
My arduino sketch:
#include <SM130.h>
void read_serial();
SM130 rfidReader;
void setup() {
//Connect to computer
Serial.begin(9600);
//connect to SM130
rfidReader.connect(7,8);
}
void loop() {
read_serial();
}
void read_serial() {
rfidReader.seek_tag();
delay(10);
rfidReader.parse_tag();
rfidReader.set_flag();
rfidReader.print_serial();
delay(100);
}

Answer 1

/Users/scottnla/Dropbox/arduino/libraries/SM130/SM130.cpp: In
constructor 'SM130::SM130()':
/Users/scottnla/Dropbox/arduino/libraries/SM130/SM130.cpp:8: error: no
matching function for call to 'SoftwareSerial::SoftwareSerial()'
This part tells you everything. SoftwareSerial has no constructor without argument list, so you try to call a non-existing function.
If you don't specify a class member in constructor's initialization list, compiler by default calls () constructor for it. It is equivalent of:
SoftwareSerial ss;
if we weren't talking about classes.
http://www.cprogramming.com/tutorial/initialization-lists-c++.html
Unfortunately SoftwareSerial has no Set methods.
http://arduino.cc/de/Reference/SoftwareSerial
But worry not, dynamic memory allocation comes to the rescue! For example:
SM130.h
#ifndef SM130_h
#define SM130_h
#include<Arduino.h>
#include <WConstants.h>
class SM130 {
public:
SM130();
~SM130();
void connect(int RX, int TX);
void check_for_notag();
void halt_tag();
void parse_tag();
void print_serial();
void seek_tag();
void set_flag();
private:
int rfid_flag;
int data[11];
SoftwareSerial* rfid;
};
#endif
SM130.cpp (only some methods)
SM130::SM130() : rfid(NULL) {
rfid_flag = 0;
}
void SM130::connect(int RX, int TX) {
if(!Serial.available())
{
Serial.begin(9600);
}
Serial.println("Connecting to SM130 RFID Reader...");
if (NULL != rfid)
{
delete rfid;
}
rfid = new SoftwareSerial(RX, TX)
rfid->begin(19200);
if(rfid->available())
{
rfid->println("Connected to SM130 RFID Reader!");
}
delay(10);
}
~SM130::SM130()
{
if (NULL != rfid)
{
delete rfid;
}
}
I only posted my versions of constructor, connect and destructor (good to have it for avoiding memory leaks).
Don't forget about:
Checking if rfid is not NULL (better use NULL != rfid instead of rfid != NULL, because compiler will tell you about mistakes like if (rfid = NULL))
Changing rfid. to rfid->
You can even add disconnect method, which deletes old rfid and sets pointer to NULL:
void SM130::disconnect() {
delete rfid;
rfid = NULL;
}