Portable and maintable HD44780 driver files.

2000-02-21 11:24:09 +00:00
parent 6cefefd52c
commit e481f1311e
12 changed files with 978 additions and 0 deletions
@@ -0,0 +1,173 @@
+/*
+ * Serial LPT driver module for Hitachi HD44780 based LCD displays by
+ * Andrew McMeikan. The LCD is operated in it's 4 bit-mode through a
+ * 4094 shift register and supports a keypad.
+ *
+ * Copyright (c)  1999 Andrew McMeikan <andrewm@engineer.com>
+ *		  modular driver 1999 Benjamin Tse <blt@Comports.com> 
+ *
+ * Full connection details at http://members.xoom.com/andrewmuck/LCD.htm
+ *
+ * printer port	  4094/LCD
+ * D2 (4)	  EN  (6 - LCD)
+ * D3 (5)	  D   (2 - 4094)
+ * D4 (6)	  CLK (3 - 4094)
+ * +Vcc		  OE, STR (15, 1 - 4094)
+ * D7 (9)	  EN2 (6 - LCD2) (optional)
+ *
+ * 4094		  LCD
+ * Q1 (4)	  D4 (11)
+ * Q2 (5)	  D5 (12)
+ * Q3 (6)	  D6 (13)
+ * Q4 (7)	  D7 (14)
+ * Q6 (13)	  RS (4)
+ * Gnd		  nRW (5)
+ *
+ * This file is released under the GNU General Public License. Refer to the
+ * COPYING file distributed with this package.
+ */
+
+#include "hd44780-serialLpt.h"
+#include "port.h"
+
+// Hardware specific functions
+void lcdserLpt_HD44780_senddata(unsigned char displayID, 
+				unsigned char flags, 
+				unsigned char ch);
+
+static char lcdserLpt_HD44780_getkey(void);
+void rawshift(unsigned char r);
+void shiftreg(unsigned char displayID, unsigned char r);
+
+#define RS	16
+#define LCDDATA 8
+#define LCDCLOCK 16
+#define EN1	4
+#define EN2	32
+
+
+static unsigned int lp;
+static char lastkey=0;
+
+
+// Initialisation
+int hd_init_serialLpt(HD44780_functions *hd44780_functions, 
+		      lcd_logical_driver *driver, 
+		      char *args, 
+		      unsigned int port)
+{
+  int displayID = EN1 | EN2;
+
+  lp = port;
+
+  hd44780_functions->senddata   = lcdserLpt_HD44780_senddata;
+
+  // TODO: enable keypad only if specified on command line
+  driver->getkey = lcdserLpt_HD44780_getkey;
+
+  // setup the lcd in 4 bit mode
+  shiftreg(displayID,3);
+  hd44780_functions->uPause(4100);
+
+  shiftreg(displayID,3);
+  hd44780_functions->uPause(100);
+
+  shiftreg(displayID,3);
+  hd44780_functions->uPause(40);
+
+  shiftreg(displayID,2);
+  hd44780_functions->uPause(40);
+
+  // set display type functions
+  lcdserLpt_HD44780_senddata(0, 
+			     RS_INSTR, 
+			     FUNCSET | IF_4BIT | TWOLINE | SMALLCHAR);
+  // clear
+  lcdserLpt_HD44780_senddata(0, RS_INSTR, CLEAR);
+  hd44780_functions->uPause(1600);
+    // Now turn on the display
+  lcdserLpt_HD44780_senddata(displayID, 
+			     RS_INSTR, 
+			     ONOFFCTRL | DISPON | CURSOROFF | CURSORNOBLINK);
+  hd44780_functions->uPause(1600);
+
+  return 0;
+}
+
+
+void lcdserLpt_HD44780_senddata(unsigned char displayID, 
+				unsigned char flags, 
+				unsigned char ch)
+{
+  unsigned char dispID = 0, 
+    portControl = 0,
+    h = ch >> 4,
+    l = ch & 15;
+
+  if (displayID == 1)
+    dispID |= EN1;
+  else if (displayID == 2)
+    dispID |= EN2;
+  else
+    dispID |= EN1 | EN2;
+
+  if (flags == RS_DATA)
+    portControl = RS;
+  else
+    portControl = 0;
+
+  shiftreg(displayID,flags | portControl | h); 
+  shiftreg(displayID,flags | portControl | l); 
+
+  /* TODO: instead of delay read keys here */
+}
+
+char lcdserLpt_HD44780_getkey()
+{
+  // TODO: a keypad scan that does not use shift register
+  // define a key table 
+  char keytr[]="ABCDEFGH";
+  int n;
+
+  rawshift(0);			//send all line on shift register low
+  hd44780_functions->uPause(1);
+  if ((port_in(lp+1)&32)==0)	//test if line back is low - if not return(0)
+  {	//else 
+    //start walking a single zero across the eight lines 
+    for(n=7;n>=0;n--)
+    {
+      rawshift(255 - (1<<n));
+      hd44780_functions->uPause(1);
+		
+      if ((port_in(lp+1)&32)==0)	// check if line back is low if yes debounce 
+      {
+	if (lastkey==keytr[n])
+	  return(0);
+	//	printf("key is %c %d\n",keytr[n],n);
+	lastkey=keytr[n];
+	return(keytr[n]);	//return correct key code.
+      }
+    }
+  }	//else fall out and return(0) [too transient a keypress]
+  lastkey=0;
+  return(0);
+}
+
+/* this function sends r out onto the shift register */
+void rawshift (unsigned char r)
+{
+  int i;			
+  for (i=7;i>=0;i--)		/* MSB first	*/
+  {
+    port_out(lp,((r>>i)&1)*LCDDATA);		/*set up data	*/
+    port_out(lp,(((r>>i)&1)*LCDDATA)|LCDCLOCK);/*rising edge of clock	*/
+  }
+}
+
+// displayID = value on parallel port to toggle the correct display
+void shiftreg (unsigned char displayID, unsigned char r)
+{				
+  rawshift(r);
+  port_out(lp,displayID);	//latch it, to correct display
+  port_out(lp,0);
+}