hd44780.c

嵌入式linux下液晶编程院代码, 可以在LINUX2.4内核下运行

/* $Id: HD44780.c,v 1.41 2003/09/13 06:20:39 reinelt Exp $
 *
 * driver for display modules based on the HD44780 chip
 *
 * Copyright 1999, 2000 by Michael Reinelt ([e-mail])
 *
 * Modification for 4-Bit mode
 * 2003 Martin Hejl ([e-mail])
 *
 * Modification for 2nd controller support
 * 2003 Jesse Brook Kovach <[e-mail]>
 *
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2, or (at your option)
 * any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 *
 *
 * $Log: HD44780.c,v $
 * Revision 1.41  2003/09/13 06:20:39  reinelt
 * HD44780 timings changed; deactivated libtool
 *
 * Revision 1.40  2003/09/11 04:09:52  reinelt
 * minor cleanups
 *
 * Revision 1.39  2003/09/10 03:48:22  reinelt
 * Icons for M50530, new processing scheme (Ticks.Text...)
 *
 * Revision 1.38  2003/09/09 11:47:47  reinelt
 * basic icon support for HD44780
 *
 * Revision 1.37  2003/09/09 06:54:43  reinelt
 * new function 'cfg_number()'
 *
 * Revision 1.36  2003/08/24 05:17:58  reinelt
 * liblcd4linux patch from Patrick Schemitz
 *
 * Revision 1.35  2003/08/22 03:45:08  reinelt
 * bug in parallel port code fixed, more icons stuff
 *
 * Revision 1.34  2003/08/19 05:23:55  reinelt
 * HD44780 dual-controller patch from Jesse Brook Kovach
 *
 * Revision 1.33  2003/08/19 04:28:41  reinelt
 * more Icon stuff, minor glitches fixed
 *
 * Revision 1.32  2003/08/16 07:31:35  reinelt
 * double buffering in all drivers
 *
 * Revision 1.31  2003/08/15 07:54:07  reinelt
 * HD44780 4 bit mode implemented
 *
 * Revision 1.30  2003/08/12 05:10:31  reinelt
 * first version of HD44780 4Bit-Mode patch
 *
 * Revision 1.29  2003/07/24 04:48:09  reinelt
 * 'soft clear' needed for virtual rows
 *
 * Revision 1.28  2003/04/07 06:02:58  reinelt
 * further parallel port abstraction
 *
 * Revision 1.27  2003/04/04 06:01:59  reinelt
 * new parallel port abstraction scheme
 *
 * Revision 1.26  2003/02/22 07:53:09  reinelt
 * cfg_get(key,defval)
 *
 * Revision 1.25  2002/08/19 09:11:34  reinelt
 * changed HD44780 to use generic bar functions
 *
 * Revision 1.24  2002/08/19 07:36:29  reinelt
 *
 * finished bar.c, USBLCD is the first driver that uses the generic bar functions
 *
 * Revision 1.23  2002/08/19 04:41:20  reinelt
 * introduced bar.c, moved bar stuff from display.h to bar.h
 *
 * Revision 1.22  2002/08/17 14:14:21  reinelt
 *
 * USBLCD fixes
 *
 * Revision 1.21  2002/04/30 07:20:15  reinelt
 *
 * implemented the new ndelay(nanoseconds) in all parallel port drivers
 *
 * Revision 1.20  2001/09/09 12:26:03  reinelt
 * GPO bug: INIT is _not_ inverted
 *
 * Revision 1.19  2001/03/15 15:49:22  ltoetsch
 * fixed compile HD44780.c, cosmetics
 *
 * Revision 1.18  2001/03/15 09:47:13  reinelt
 *
 * some fixes to ppdef
 * off-by-one bug in processor.c fixed
 *
 * Revision 1.17  2001/03/14 16:47:41  reinelt
 * minor cleanups
 *
 * Revision 1.16  2001/03/14 15:30:53  reinelt
 *
 * make ppdev compatible to earlier kernels
 *
 * Revision 1.15  2001/03/14 15:14:59  reinelt
 * added ppdev parallel port access
 *
 * Revision 1.14  2001/03/12 13:44:58  reinelt
 *
 * new udelay() using Time Stamp Counters
 *
 * Revision 1.13  2001/03/12 12:39:36  reinelt
 *
 * reworked autoconf a lot: drivers may be excluded, #define's went to config.h
 *
 * Revision 1.12  2001/02/14 07:40:16  reinelt
 *
 * first (incomplete) GPO implementation
 *
 * Revision 1.11  2001/02/13 12:43:24  reinelt
 *
 * HD_gpo() was missing
 *
 * Revision 1.10  2001/02/13 09:00:13  reinelt
 *
 * prepared framework for GPO's (general purpose outputs)
 *
 * Revision 1.9  2000/10/20 07:17:07  reinelt
 *
 *
 * corrected a bug in HD_goto()
 * Thanks to Gregor Szaktilla <[e-mail]>
 *
 * Revision 1.8  2000/08/10 09:44:09  reinelt
 *
 * new debugging scheme: error(), info(), debug()
 * uses syslog if in daemon mode
 *
 * Revision 1.7  2000/08/09 09:50:29  reinelt
 *
 * opened 0.98 development
 * removed driver-specific signal-handlers
 * added 'quit'-function to driver structure
 * added global signal-handler
 *
 * Revision 1.6  2000/07/31 10:43:44  reinelt
 *
 * some changes to support kernel-2.4 (different layout of various files in /proc)
 *
 * Revision 1.5  2000/07/31 06:46:35  reinelt
 *
 * eliminated some compiler warnings with glibc
 *
 * Revision 1.4  2000/04/15 16:56:52  reinelt
 *
 * moved delay loops to udelay.c
 * renamed -d (debugging) switch to -v (verbose)
 * new switch -d to calibrate delay loop
 * 'Delay' entry for HD44780 back again
 * delay loops will not calibrate automatically, because this will fail with hich CPU load
 *
 * Revision 1.3  2000/04/15 11:13:54  reinelt
 *
 * added '-d' (debugging) switch
 * added several debugging messages
 * removed config entry 'Delay' for HD44780 driver
 * delay loop for HD44780 will be calibrated automatically
 *
 * Revision 1.2  2000/04/13 06:09:52  reinelt
 *
 * added BogoMips() to system.c (not used by now, maybe sometimes we can
 * calibrate our delay loop with this value)
 *
 * added delay loop to HD44780 driver. It seems to be quite fast now. Hopefully
 * no compiler will optimize away the delay loop!
 *
 * Revision 1.1  2000/04/12 08:05:45  reinelt
 *
 * first version of the HD44780 driver
 *
 */

/* 
 *
 * exported fuctions:
 *
 * struct LCD HD44780[]
 *
 */

#include "config.h"

#include <stdlib.h>
#include <stdio.h>
#include <string.h>

#include "debug.h"
#include "cfg.h"
#include "display.h"
#include "bar.h"
#include "icon.h"
#include "parport.h"
#include "udelay.h"

#define XRES 5
#define YRES 8
#define CHARS 8



/* low level communication timings [nanoseconds]
 * as these values differ from spec to spec,
 * we use the worst-case values.
 */

#define T_CYCLE 1000 // Enable cycle time
#define T_PW     450 // Enable pulse width
#define T_AS      60 // Address setup time
#define T_H       40 // Data hold time


/* HD44780 execution timings [microseconds]
 * as these values differ from spec to spec,
 * we use the worst-case values.
 */

#define T_INIT1 4100 // first init sequence:  4.1 msec
#define T_INIT2  100 // second init sequence: 100 usec
#define T_EXEC    80 // normal execution time
#define T_WRCG   120 // CG RAM Write
#define T_CLEAR 1640 // Clear Display


static LCD Lcd;
static int Icons;
static int Bits=0;
static int GPO=0;
static int Controllers = 0;
static int Controller  = 0;

static char *FrameBuffer1=NULL;
static char *FrameBuffer2=NULL;

static unsigned char SIGNAL_RW;
static unsigned char SIGNAL_RS;
static unsigned char SIGNAL_ENABLE;
static unsigned char SIGNAL_ENABLE2;
static unsigned char SIGNAL_GPO;

static void HD_nibble(unsigned char controller, unsigned char nibble)
{
  unsigned char enable;

  // enable signal: 'controller' is a bitmask
  // bit 0 .. send to controller #0
  // bit 1 .. send to controller #1
  // so we can send a byte to both controllers at the same time!
  enable=0;
  if (controller&0x01) enable|=SIGNAL_ENABLE;
  if (controller&0x02) enable|=SIGNAL_ENABLE2;
  
  // clear ENABLE
  // put data on DB1..DB4
  // nibble already contains RS bit!
  parport_data(nibble);

  // Address set-up time
  ndelay(T_AS);
  
  // rise ENABLE
  parport_data(nibble | enable);
  
  // Enable pulse width
  ndelay(T_PW);

  // lower ENABLE
  parport_data(nibble);
}


static void HD_byte (unsigned char controller, unsigned char data, unsigned char RS)
{
  // send high nibble of the data
  HD_nibble (controller, ((data>>4)&0x0f)|RS);

  // Make sure we honour T_CYCLE
  ndelay(T_CYCLE-T_AS-T_PW);

  // send low nibble of the data
  HD_nibble(controller, (data&0x0f)|RS);
}


static void HD_command (unsigned char controller, unsigned char cmd, int delay)
{
  unsigned char enable;
   
  if (Bits==8) {
    
    // enable signal: 'controller' is a bitmask
    // bit 0 .. send to controller #0
    // bit 1 .. send to controller #1
    // so we can send a byte to both controllers at the same time!
    enable=0;
    if (controller&0x01) enable|=SIGNAL_ENABLE;
    if (controller&0x02) enable|=SIGNAL_ENABLE2;
    
    // put data on DB1..DB8
    parport_data (cmd);
  
    // clear RW and RS
    parport_control (SIGNAL_RW | SIGNAL_RS, 0);
    
    // Address set-up time
    ndelay(T_AS);

    // send command
    parport_toggle (enable, 1, T_PW);
    
  } else {

    HD_byte (controller, cmd, 0);

  }
  
  // wait for command completion
  udelay(delay);