Cannot use HardwareSerial pointers or references in the Lib for Arduino AVR

arduinoclibrary

I wrote a wrapper class for a serial lcd screen for 4dulcd – and i want to be able to pass which serial i am using to communicate with it

I have these in my code
myClass.h

#include <HardwareSerial.h>

public:
uint8_t Init(long BaudRate, HardwareSerial *serial);

private:
HardwareSerial *_HardSerial;

in myClass.cpp

uint8_t myClass::Init(long BaudRate, HardwareSerial *serial){
_HardSerial(serial);
...
}

In my sketch

#include <myClass.h>  
myClass lcd;  


void setup()
{
  Serial1.begin(9600);  // <- Error here?!
  //lcd.Init(115000,&Serial1);
...

So the error is

sketch_sep17a.cpp: In function 'void setup()': sketch_sep17a:16:
error: 'Serial1' was not declared in this scope

If i remove the myClass.h header than the Serial1 works… i Include it and it throws this error that makes no sense to-

I tried to include the hardwareserial in my sketch and make an instance of it but it requires all sorts of construction properties that i have no idea what they mean. And i would not even want to release my lib to do this as it is inconvenient for the normal end user.

I tried both references and pointers- same error.

Can any body help?

Best Answer

I might be missing something here, but where is Serial1 instantiated?

If there is no Serial1 object created then unless the begin function is static it won't work.

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Electronic – arduino – How to know when making a library for the Arduino

I'll take a stab. I haven't written code for Arduino, but I've done a lot of C and C++ programming. It would help if I actually saw your errors, but nonetheless.

The main thing you need to always remember when using C++ with C code is that your C++ code needs functions declared with "extern "C"" if you want C code to be able to link against the C++ code. The "extern "C"" is what tells the C++ compiler that I'm creating linkable code for C files or I'm using code from C files. So all your functions in the library API header should correlate with a function in the source file defined liked "extern "C" void dosomething()". If you're trying to use classes in C++, remember that C code can't call it, you'll need to create functions (extern "C") to access the object. Now, if your C code is compiled with a C++ compiler, then don't worry about "extern "C"".

If you want to call C code inside your C++ code, then you need to wrap the C header with a construct like this:

#ifdef ___cplusplus
extern "C" {
#endif

///all my C function declarations... yada yada

#ifdef __cplusplus
}  //end extern "C"
#endif

If you working in C++, don't use a lot a #defines unless you're creating compile-time flags like "DEBUG" or "VERSION2" to create special sets of code. Otherwise use "const int/char/float" for number defines for safe type checking. The compilers are usually smart enough to optimize these out, so they wind up in ROM/code space (depends though). Also, don't create MACROS, use inline functions. Also, don't always follow convention when programming if it's stupid such as using a lot of macros and number defines in C++. The same thing applies to C99 version of C, it has added things like inline functions and consts from C++. The industry realizes how much buggy code and hard to maintain code comes from overuse of the preprocessor language.

Eclipse usually stores the obj files in a directory under your project. If you're doing a "Debug" build, then it's located under the "Debug" folder under your project folder. If you're doing a "Release" build, then look under "Release", etc. Normally a clean build just works for me in Eclipse, so I don't know what's going wrong with your setup. I guess make sure you're not creating precompiled headers.

Electronic – arduino – What’s wrong with the C++ Template code for Arduino

You need to move the contents of the .cpp file into the .h file. Separating declarations and definitions doesn't work for templates. See the link @sharptooth posted: https://stackoverflow.com/q/648900.

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