HD44780 LCD controller

Detailed Description

This class implements a HD44780 LCD controller.

Header file:

#include <hwa/ext/hd44780.h>

Constructor

HW_HD44780(...) declares a HD44780 object. You must provide:

• the number of display lines;
• the number of display columns;
• the I/O the 'e' pin is connected to;
• the I/O the 'rs' pin is connected to;
• the I/O the 'rw' pin is connected to;
• the I/O the 'data' pins are connected to.

#define PCF          HW_PCF8574( interface, twi0, address, 0x27 )
 
#define LCD          HW_HD44780( lines, 2,           \
                                 cols,  16,          \
                                 e,     (PCF, 1, 2), \
                                 rs,    (PCF, 1, 0), \
                                 rw,    (PCF, 1, 1), \
                                 data,  (PCF, 4, 4) )

Currently, HWA supports only the driving of the HD44780 in 4-bit mode through a single dedicated I²C bus expander PCF8574.

The implementation of this device focuses on code size rather than on speed, so it relies on extern C functions rather than on inlined code. You must use HW_IMPLEMENT() to have these functions defined.

HW_DECLARE( LCD ) declares the functions that implement the device. You can put it in your header files:

HW_DECLARE( LCD );

HW_IMPLEMENT( LCD ) defines the functions that implement the device. This must appear in one of your source files:

HW_IMPLEMENT( LCD );

Relatives

• (LCD,putchar): the name of the putchar function associated to the LCD.

HW(LCD,putchar)('x');        //  Write 'x' on the LCD using its putchar function

Assuming that myprintf takes the address of a putchar function as first argument:

myprintf( HW(LCD,putchar), "ADC=%03d\n", hw(read,adc0));

Actions

hw( configure, LCD, ... ) configures the LCD:

hw(   configure, LCD,
 
    [ init,      yes | no, ]         // Initialize (no)
 
    [ display,   on | off,           // Text visibility (on)
      cursor,    on | off,           // '_' visibility (off)
      blink,     on | off, ]         // Blinking block (off)
 
    [ shift,     cursor | display,   //
      direction, left | right ]      //
   );

hw( cls, LCD ) clears the screen:

hw( cls, LCD );

hw( gotoxy, LCD, x, y ) moves the cursor to column x, line y:

hw( gotoxy, LCD, x, y );

hw( newline, LCD ) moves the cursor to the start of the next line:

hw( newline, LCD, pos );

hw( home, LCD ) moves the cursor to the home position:

hw( home, LCD );

hw( putchar, LCD, c ) writes a character at the current position:

hw( putchar, LCD, c );

Macros
#define	HW_DECLARE__hd44780
#define	HW_HD44780(...)
#define	HW_IMPLEMENT__hd44780