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hd44780-winamp.c

/*
 * "Winamp" 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 Andrew McMeikan <andrewm@engineer.com>
 *            modular driver 1999-2000 Benjamin Tse <blt@Comports.com>
 *
 *            Modified July 2000 by Charles Steinkuehler for enhanced
 *            performance and reduced CPU usage
 *              - provided required setup time for RS valid to E high
 *              - 1 uS call to uPause removed as it is unnecessary
 *
 *                2001 Joris Robijn <joris@robijn.net>
 *                  - Keypad support
 *
 * 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)      EN (6)
 * nLF   (14)     nRW (5) (EN3 6 - LCD 3) (optional)
 * INIT  (16)     RS (4)
 * nSEL  (17)     EN2 (6 - LCD 2) (optional)
 *
 * 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
 * nLF    (14)    Y8
 * INIT   (16)    Y9
 * nSEL   (17)    Y10
 * 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>
 *
 * This file is released under the GNU General Public License. Refer to the
 * COPYING file distributed with this package.
 */

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

#include "port.h"
#include "shared/str.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 lcdwinamp_HD44780_senddata (unsigned char displayID, unsigned char flags, unsigned char ch);
void lcdwinamp_HD44780_backlight (unsigned char state);
unsigned char lcdwinamp_HD44780_readkeypad (unsigned int YData);

#define EN1 STRB
#define EN2 SEL
#define EN3 LF
#define RW  LF
#define RS  INIT
#define BL  SEL

static unsigned char EnMask[] = { EN1, EN2, EN3 };

static unsigned int lptPort;
static char stuckinputs = 0;  // if an input line is stuck, it will be ignored
static char backlight_bit = 0;      // default to low to enable two displays

// initialise the driver
int
hd_init_winamp (HD44780_functions * hd44780_functions, lcd_logical_driver * driver, char *args, unsigned int port)
{
      // Reserve the port registers
      lptPort = port;
      port_access(lptPort);
      port_access(lptPort+1);
      port_access(lptPort+2);

      hd44780_functions->senddata = lcdwinamp_HD44780_senddata;
      hd44780_functions->backlight = lcdwinamp_HD44780_backlight;
      hd44780_functions->readkeypad = lcdwinamp_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 ();
      return 0;
}

// lcdwinamp_HD44780_senddata
void
lcdwinamp_HD44780_senddata (unsigned char displayID, unsigned char flags, unsigned char ch)
{
      unsigned char enableLines = 0, portControl;

      if (flags == RS_DATA)
            portControl = RS;
      else
            portControl = 0;

      portControl |= backlight_bit;

      if (displayID == 0)
            enableLines = EnMask[0] | EnMask[1] | ((extIF) ? EnMask[2] : 0);
      else
            enableLines = EnMask[displayID - 1];

      // 40 nS setup time for RS valid to EN high, so set RS
      port_out (lptPort + 2, portControl ^ OUTMASK);

      // Output the actual data
      port_out (lptPort, ch);

      if( delayBus ) hd44780_functions->uPause (1);

      // then set EN high
      port_out (lptPort + 2, (enableLines|portControl) ^ OUTMASK);

      if( delayBus ) hd44780_functions->uPause (1);

      // 80 nS setup from valid data to EN low will be met without any delay
      // unless you are running a REALLY FAST ISA bus (like 75 MHZ!)
      // 230 nS minimum E high time provided by ISA bus delays as well...

      // ABOVE TEXT ignored now, using delays if delayBus is specified

      // Set EN low and we're done...
      port_out (lptPort + 2, portControl ^ OUTMASK);

      // 10 nS data hold time provided by the length of ISA write for EN
}

void lcdwinamp_HD44780_backlight (unsigned char state)
{
      backlight_bit = (state?0:nSEL);

      port_out (lptPort + 2, backlight_bit ^ OUTMASK);
}

unsigned char lcdwinamp_HD44780_readkeypad (unsigned int YData)
{
      unsigned char readval;

      // 8 bits output
      // Convert the positive logic to the negative logic on the LPT port
      port_out (lptPort, ~YData & 0x00FF );

      if( delayBus ) hd44780_functions->uPause (1);

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

      // Set output back to idle state for backlight
      port_out (lptPort + 2, backlight_bit ^ OUTMASK );

      // 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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