174 lines
4.1 KiB
C
174 lines
4.1 KiB
C
/*
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* Serial LPT driver module for Hitachi HD44780 based LCD displays by
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* Andrew McMeikan. The LCD is operated in it's 4 bit-mode through a
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* 4094 shift register and supports a keypad.
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*
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* Copyright (c) 1999 Andrew McMeikan <andrewm@engineer.com>
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* modular driver 1999 Benjamin Tse <blt@Comports.com>
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*
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* Full connection details at http://members.xoom.com/andrewmuck/LCD.htm
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*
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* printer port 4094/LCD
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* D2 (4) EN (6 - LCD)
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* D3 (5) D (2 - 4094)
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* D4 (6) CLK (3 - 4094)
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* +Vcc OE, STR (15, 1 - 4094)
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* D7 (9) EN2 (6 - LCD2) (optional)
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*
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* 4094 LCD
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* Q1 (4) D4 (11)
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* Q2 (5) D5 (12)
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* Q3 (6) D6 (13)
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* Q4 (7) D7 (14)
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* Q6 (13) RS (4)
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* Gnd nRW (5)
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*
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* This file is released under the GNU General Public License. Refer to the
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* COPYING file distributed with this package.
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*/
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#include "hd44780-serialLpt.h"
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#include "port.h"
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// Hardware specific functions
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void lcdserLpt_HD44780_senddata(unsigned char displayID,
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unsigned char flags,
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unsigned char ch);
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static char lcdserLpt_HD44780_getkey(void);
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void rawshift(unsigned char r);
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void shiftreg(unsigned char displayID, unsigned char r);
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#define RS 16
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#define LCDDATA 8
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#define LCDCLOCK 16
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#define EN1 4
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#define EN2 32
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static unsigned int lp;
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static char lastkey=0;
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// Initialisation
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int hd_init_serialLpt(HD44780_functions *hd44780_functions,
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lcd_logical_driver *driver,
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char *args,
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unsigned int port)
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{
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int displayID = EN1 | EN2;
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lp = port;
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hd44780_functions->senddata = lcdserLpt_HD44780_senddata;
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// TODO: enable keypad only if specified on command line
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driver->getkey = lcdserLpt_HD44780_getkey;
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// setup the lcd in 4 bit mode
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shiftreg(displayID,3);
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hd44780_functions->uPause(4100);
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shiftreg(displayID,3);
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hd44780_functions->uPause(100);
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shiftreg(displayID,3);
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hd44780_functions->uPause(40);
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shiftreg(displayID,2);
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hd44780_functions->uPause(40);
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// set display type functions
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lcdserLpt_HD44780_senddata(0,
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RS_INSTR,
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FUNCSET | IF_4BIT | TWOLINE | SMALLCHAR);
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// clear
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lcdserLpt_HD44780_senddata(0, RS_INSTR, CLEAR);
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hd44780_functions->uPause(1600);
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// Now turn on the display
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lcdserLpt_HD44780_senddata(displayID,
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RS_INSTR,
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ONOFFCTRL | DISPON | CURSOROFF | CURSORNOBLINK);
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hd44780_functions->uPause(1600);
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return 0;
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}
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void lcdserLpt_HD44780_senddata(unsigned char displayID,
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unsigned char flags,
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unsigned char ch)
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{
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unsigned char dispID = 0,
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portControl = 0,
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h = ch >> 4,
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l = ch & 15;
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if (displayID == 1)
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dispID |= EN1;
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else if (displayID == 2)
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dispID |= EN2;
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else
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dispID |= EN1 | EN2;
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if (flags == RS_DATA)
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portControl = RS;
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else
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portControl = 0;
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shiftreg(displayID,flags | portControl | h);
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shiftreg(displayID,flags | portControl | l);
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/* TODO: instead of delay read keys here */
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}
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char lcdserLpt_HD44780_getkey()
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{
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// TODO: a keypad scan that does not use shift register
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// define a key table
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char keytr[]="ABCDEFGH";
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int n;
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rawshift(0); //send all line on shift register low
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hd44780_functions->uPause(1);
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if ((port_in(lp+1)&32)==0) //test if line back is low - if not return(0)
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{ //else
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//start walking a single zero across the eight lines
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for(n=7;n>=0;n--)
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{
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rawshift(255 - (1<<n));
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hd44780_functions->uPause(1);
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if ((port_in(lp+1)&32)==0) // check if line back is low if yes debounce
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{
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if (lastkey==keytr[n])
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return(0);
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// printf("key is %c %d\n",keytr[n],n);
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lastkey=keytr[n];
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return(keytr[n]); //return correct key code.
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}
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}
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} //else fall out and return(0) [too transient a keypress]
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lastkey=0;
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return(0);
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}
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/* this function sends r out onto the shift register */
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void rawshift (unsigned char r)
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{
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int i;
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for (i=7;i>=0;i--) /* MSB first */
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{
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port_out(lp,((r>>i)&1)*LCDDATA); /*set up data */
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port_out(lp,(((r>>i)&1)*LCDDATA)|LCDCLOCK);/*rising edge of clock */
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}
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}
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// displayID = value on parallel port to toggle the correct display
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void shiftreg (unsigned char displayID, unsigned char r)
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{
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rawshift(r);
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port_out(lp,displayID); //latch it, to correct display
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port_out(lp,0);
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}
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