Use of Serial in a Library

Projects Programming
1

I'm writing a library that writes to a VFD (vacuum fluorescent display), and would like to take advantage of Print. I looked at the LiquidCrystal library as an example, except the VFD uses a serial interface. However, the Serial functions, in a library, does not seem to work - no rx or tx leds during usage. After searching, found this read-only topic: Arduino Forum

It suggests: "This code allows you to use any library that inherits the Print object. [ethernet serial softwareserial etc etx]" and proceeds to add a MyLibrary class that inherits the Print object.

I'm not sure this is the way to go for writing a shared library, and after all, none of the LiquidCrystal examples have this. Is there a good solution to creating a library that uses Serial and a member of the Print class? Thanks!

2

http://arduino.cc/playground/Code/Printclass

Note that that is a little bit dated; the functions should return size_t rather than void.

3

Derive your class from Stream and then implement the virtual functions. I did that here for example:

class DebugOutput : public Stream
{
private:
  // blah blah
  
public:
  void begin () {   }   // whatever

  virtual int available (void);
  virtual int peek (void);
  virtual int read (void);
  virtual void flush (void);
  virtual size_t write (byte c);
    
  using Print::write; // pull in write(str) and write(buf, size) from Print
  
};  // end of DebugOutput
4

However, the Serial functions, in a library, does not seem to work - no rx or tx leds during usage.

The RX and TX LEDs are controlled by the USB to serial converter. You're not using that, are you? So, why do you expect it to blink the LEDs?