hwa/atmel/avr/examples/99-03-HD44780-PCF8574/main.c

Drive a LCD through a HD44780 controller connected to a PCF8574 TWI

This example shows how HWA deals with external hardware. Here, a HD44780-based LCD controller is driven through a PCF8574 I²C bus expander connected to a two-wire interface (TWI). The TWI can be embedded into the MCU or software-emulated.

config.h

 
/*  This file is part of the HWA project.
 *  Copyright (c) 2018 Christophe Duparquet.
 *  All rights reserved. Read LICENSE.TXT for details.
 */
 
/*  Include the target board (and device) definitions
 */
#include BOARD_H
 
#include <hwa/ext/swtwimaster.h>
#include <hwa/ext/pcf8574.h>
#include <hwa/ext/hd44780.h>
 
#if HW_ADDRESS(twi0) != -1
#  define TWI           twi0
#else
#  define TWI           HW_SWTWIMASTER( scl, (portc,5), \
                                        sda, (portc,4), \
                                        bps, TWI_BPS )
#endif
 
#define TWI_BPS         100000
 
#define LCD             HW_HD44780( lines, 2,                   \
                                    cols,  16,                  \
                                    e,     (PCF, 1, 2),         \
                                    rs,    (PCF, 1, 0),         \
                                    rw,    (PCF, 1, 1),         \
                                    data,  (PCF, 4, 4) )
 
/* #define LCD          HW_HD44780( lines, 2,                   \ */
/*                                  cols,  16,                  \ */
/*                                  e,     (portb,2),                   \ */
/*                                  rs,    (portb,0),                   \ */
/*                                  rw,    (portb,1),                   \ */
/*                                  data,  (port1,4,4) ) */
 
#define PCF             HW_PCF8574( interface, TWI, address, 0x27 )
 
#define LCD_LED         (PCF, 1, 3)
 
HW_DECLARE( TWI );
HW_DECLARE( PCF );
HW_DECLARE( LCD );

main.c

 
/*  This file is part of the HWA project.
 *  Copyright (c) 2018 Christophe Duparquet.
 *  All rights reserved. Read LICENSE.TXT for details.
 */
 
#include "config.h"
#include "xprintf.h"
 
 
HW_IMPLEMENT(TWI);
HW_IMPLEMENT(PCF);
HW_IMPLEMENT(LCD);
 
 
int main(void)
{
  hw( configure, TWI, bps, TWI_BPS );
  hw( configure, PCF );
 
  hw( clear, LCD_LED );
 
  hw( configure, LCD,
      init,      yes,
      display,   on ,
      cursor,    off,
      blink,     off,
      shift,     cursor,
      direction, right );
 
  hw( write, LCD_LED, 1 );
 
  while(1) {
    int i = 0;
    int line = 0;
    for(i=0; i<1000 ; i++) {
 
      if ( line == 0 ) {
        hw( gotoxy, LCD, 0, line );
        xprintf( HW(LCD,putchar), " g=%3d", i);
      }
      else {
        hw( gotoxy, LCD, 8, line );
        xprintf( HW(LCD,putchar), " g=%03d", i);
      }
 
      line++;
      line %= 2;
      hw_waste_cycles( 0.25 * HW_SYSHZ );
    }
  }
}