How to construct a library with digital out pins.

Questions » How to construct a library with digital out pins.

10 years, 11 months ago.

I want to construct a library (properly for Mbed) that drives a LCD display using 3 DigitalOut pins.

I can add my code in later but not sure of the correct way to set this out and define the pins in the constructor. I'm using the following files:

main program

#include "mbed.h"
#include "9digitLCD.h"

9digitLCD lcd(PTC0,PTC1,PTD6); // WO, CS, DATA

int main()
{
     
    while(1){}
    
}

9digitLCD.h

#include "mbed.h"



class 9digitLCD : public Stream {
    
public:

    9digitLCD(PinName WO, PinName CS, PinName DATA); // Default constructor
  


private:
    
    DigitalOut  WO;
    DigitalOut  CS;
    DigitalOut  DATA;   
};

9digitLCD.cpp

#include "9digitLCD.h"


9digitLCD::9digitLCD(PinName WO, PinName CS, PinName DATA) : _WO(pin),_CS(pin),_DATA(pin){initialise_display();}

Can anyone help just to get me started with this Generally I chop and change existing libraries, but its about time I do my own.

Many thanks

Paul

1 Answer

10 years, 11 months ago.

Hi, Paul-san,

Following is my trial.

Typing 0 from the terminal turn LED to white, 7 to dim...

#ifndef _RGBLED_H_
#define _RGBLED_H_

class RGBLED {
public:
    RGBLED(PinName RedPin, PinName GreenPin, PinName BluePin) ;
    ~RGBLED() ;
    
    void write(int value) ;
    int read(void) ;
    
    #ifdef MBED_OPERATORS
    /** A shorthand for write()
     */
    RGBLED& operator= (int value) {
        write(value);
        return *this;
    }

    RGBLED& operator= (RGBLED& rhs) {
        write(rhs.read());
        return *this;
    }

    /** A shorthand for read()
     */
    operator int() {
        return read();
    }
#endif

private:
    DigitalOut _R ;
    DigitalOut _G ;
    DigitalOut _B ;
} ;
#endif /* _RGBLED_H_ */

#include "mbed.h"
#include "RGBLED.h"

RGBLED::RGBLED(PinName RedPin, PinName GreenPin, PinName BluePin) : _R(RedPin), _G(GreenPin), _B(BluePin)
{
    // for the initial value, I want dim all three
    _R = 1 ;
    _G = 1 ;
    _B = 1 ;
}

RGBLED::~RGBLED() 
{
    // same reason with the constructor
    _R = 1 ;
    _G = 1 ;
    _B = 1 ;
}

void RGBLED::write(int value) 
{
    _R = (value >> 2) & 0x01 ;
    _G = (value >> 1) & 0x01 ;
    _B = value & 0x01 ;
}

int RGBLED::read(void)
{
    int result ;
    result = 0x4 * _R + 0x2 * _G + _B ;
    return( result ) ;
}

#include "mbed.h"
#include "RGBLED.h"

RGBLED rgbled(PTB18, PTB19, PTD1) ; // for FRDM-KL25Z

int main() {
    int value ;
    while(1) {
        printf("> ") ;
        scanf("%d", &value) ;
        rgbled = value ;
    }
}

moto

Thank you Motoo :) I will use this example to build my code and let you know how I get on.

edit....

That worked fine, all done now, here is the result:

https://developer.mbed.org/users/star297/code/HT1621_16seg_LCD/

I took out the "~ RGBLED() ;"

Not sure why or if this is needed or why it would be needed, something to do with 'Bitwise NOT' but I can't find an example explanation for use in constructing a library.

posted by Paul Staron 14 Jan 2015

If you were asking why I added "RGBLED()", I added it only to turn all LED off. With my FRDM-KL25Z, sometimes LED left on as white, which is too dazzling for me, so I decided to turn it off, in case the destructor is called. moto

posted by Motoo Tanaka 18 Jan 2015

Paul Staron

Important changes to forums and questions

10 years, 11 months ago.