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hd44780-ext8bit.c

/*
 * 8-bit driver module for Hitachi HD44780 based LCD displays.
 * The LCD is operated in it's 8 bit-mode to be connected to a single
 * PC parallel port.
 *
 * Copyright (c)  1999, 1995 Benjamin Tse <blt@Comports.com>
 *                2001 Joris Robijn <joris@robijn.net>
 *
 * The connections are:
 * printer port   LCD
 * D0 (2)     D0 (7)
 * D1 (3)     D1 (8)
 * D2 (4)     D2 (9)
 * D3 (5)     D3 (10)
 * D4 (6)     D4 (11)
 * D5 (7)     D5 (12)
 * D6 (8)     D6 (13)
 * D7 (9)     D7 (14)
 * nSTRB (1)      RS (4)
 * nLF   (14)     RW (5) (LCD2 - 6) (optional - pull all LCD RW low)
 * INIT  (16)     EN (6)
 *
 * Backlight
 * SEL  (17)        backlight (optional, see documentation)
 *
 * Keypad connection (optional):
 * Some diodes and resistors are needed, see further documentation.
 * printer port   keypad
 * D0 (2)     Y0
 * D1 (3)     Y1
 * D2 (4)     Y2
 * D3 (5)     Y3
 * D4 (6)     Y4
 * D5 (7)     Y5
 * D6 (7)     Y6
 * D7 (7)     Y7
 * nSTRB  (1)     Y8
 * nSEL   (17)    Y9
 * nACK   (10)    X0
 * BUSY   (11)    X1
 * PAPEREND (12)  X2
 * SELIN  (13)    X3
 * nFAULT (15)    X4
 *
 * Created modular driver Dec 1999, Benjamin Tse <blt@Comports.com>
 *
 * Based on the code in the lcdtime package which uses the LCD
 * controller in its 8-bit mode.
 *
 * This file is released under the GNU General Public License. Refer to the
 * COPYING file distributed with this package.
 */

#include "hd44780-ext8bit.h"
#include "hd44780.h"
#include "lpt-port.h"

#include "port.h"
#include "lcd_sem.h"
#include <stdio.h>
#include <string.h>
#include <errno.h>

// Generally, any function that accesses the LCD control lines needs to be
// implemented separately for each HW design. This is typically (but not
// restricted to):
// HD44780_senddata
// HD44780_readkeypad

void lcdtime_HD44780_senddata (unsigned char displayID, unsigned char flags, unsigned char ch);
void lcdtime_HD44780_backlight (unsigned char state);
unsigned char lcdtime_HD44780_readkeypad (unsigned int YData);

#define RS  STRB
#define RW  LF
#define EN1 INIT
#define BL  SEL

static unsigned int lptPort;
static char stuckinputs = 0;  // if an input line is stuck, it will be ignored
static char backlight_bit = 0;

static int semid;

// initialise the driver
int
hd_init_ext8bit (HD44780_functions * hd44780_functions, lcd_logical_driver * driver, char *args, unsigned int port)
{
      semid = sem_get ();

      // Reserve the port registers
      lptPort = port;
      port_access(lptPort);
      port_access(lptPort+1);
      port_access(lptPort+2);

      hd44780_functions->senddata = lcdtime_HD44780_senddata;
      hd44780_functions->backlight = lcdtime_HD44780_backlight;
      hd44780_functions->readkeypad = lcdtime_HD44780_readkeypad;

      // setup the lcd in 8 bit mode
      hd44780_functions->senddata (0, RS_INSTR, FUNCSET | IF_8BIT);
      hd44780_functions->uPause (4100);
      hd44780_functions->senddata (0, RS_INSTR, FUNCSET | IF_8BIT);
      hd44780_functions->uPause (100);
      hd44780_functions->senddata (0, RS_INSTR, FUNCSET | IF_8BIT | TWOLINE | SMALLCHAR);
      hd44780_functions->uPause (40);

      common_init ();

      if (have_keypad) {
            // Remember which input lines are stuck
            stuckinputs = lcdtime_HD44780_readkeypad (0);
      }
      return 0;
}

// lcdtime_HD44780_senddata
void
lcdtime_HD44780_senddata (unsigned char displayID, unsigned char flags, unsigned char ch)
{
      unsigned char enableLines = 0, portControl;

      // Only one controller is supported
      enableLines = EN1;

      if (flags == RS_INSTR)
            portControl = 0;
      else //if (iflags == RS_DATA)
            portControl = RS;

      portControl |= backlight_bit;

      sem_wait (semid);
      port_out (lptPort + 2, portControl ^ OUTMASK);
      port_out (lptPort, ch);
      if( delayBus ) hd44780_functions->uPause (1);
      port_out (lptPort + 2, (enableLines|portControl) ^ OUTMASK);
      if( delayBus ) hd44780_functions->uPause (1);
      port_out (lptPort + 2, portControl ^ OUTMASK);
      sem_signal (semid);
}

void lcdtime_HD44780_backlight (unsigned char state)
{
      backlight_bit = (state?0:SEL);

      // Semaphores not needed because backlight will not go together with
      // the bacrgraph anyway...
      port_out (lptPort + 2, backlight_bit ^ OUTMASK);
}

unsigned char lcdtime_HD44780_readkeypad (unsigned int YData)
{
      unsigned char readval;

      sem_wait (semid);

      // 10 bits output or 8 bits if >=3 displays
      // Convert the positive logic to the negative logic on the LPT port
      port_out (lptPort, ~YData & 0x00FF );
      if (!extIF) {
            port_out (lptPort + 2, ( ((~YData & 0x0100) >> 8) | ((~YData & 0x0200) >> 6)) ^ OUTMASK);
      }
      if( delayBus ) hd44780_functions->uPause (1);

      // Read inputs
      readval = ~ port_in (lptPort + 1) ^ INMASK;

      // Put port back into idle state for backlight
      port_out (lptPort, backlight_bit ^ OUTMASK);
      sem_signal (semid);

      // And convert value back (MSB first).
      return (((readval & FAULT) / FAULT <<4) |       /* pin 15 */
            ((readval & SELIN) / SELIN <<3) |         /* pin 13 */
            ((readval & PAPEREND) / PAPEREND <<2) |         /* pin 12 */
            ((readval & BUSY) / BUSY <<1) |                 /* pin 11 */
            ((readval & ACK) / ACK )) & ~stuckinputs; /* pin 10 */
}

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