Diff: TextLCD.cpp

Revision:

0:ec079a141883

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/TextLCD.cpp	Fri Jul 27 15:06:59 2012 +0000
@@ -0,0 +1,151 @@
+/* mbed TextLCD Library
+ * Copyright (c) 2007-2009 sford
+ * Released under the MIT License: http://mbed.org/license/mit
+ */
+ 
+#include "TextLCD.h"
+
+#include "mbed.h"
+#include "error.h"
+
+using namespace mbed;
+
+/*
+ * useful info found at http://www.a-netz.de/lcd.en.php
+ *
+ *
+ * Initialisation
+ * ==============
+ *
+ * After attaching the supply voltage/after a reset, the display needs to be brought in to a defined state
+ *
+ * - wait approximately 15 ms so the display is ready to execute commands
+ * - Execute the command 0x30 ("Display Settings") three times (wait 1,64ms after each command, the busy flag cannot be queried now). 
+ * - The display is in 8 bit mode, so if you have only connected 4 data pins you should only transmit the higher nibble of each command.
+ * - If you want to use the 4 bit mode, now you can execute the command to switch over to this mode now.
+ * - Execute the "clear display" command
+ *
+ * Timing
+ * ======
+ *
+ * Nearly all commands transmitted to the display need 40us for execution. 
+ * Exceptions are the commands "Clear Display and Reset" and "Set Cursor to Start Position" 
+ * These commands need 1.64ms for execution. These timings are valid for all displays working with an 
+ * internal clock of 250kHz. But I do not know any displays that use other frequencies. Any time you 
+ * can use the busy flag to test if the display is ready to accept the next command.
+ * 
+ * _e is kept high apart from calling clock
+ * _rw is kept 0 (write) apart from actions that uyse it differently
+ * _rs is set by the data/command writes
+ */
+
+TextLCD::TextLCD(PinName rs, PinName rw, PinName e, PinName d0, PinName d1, 
+	PinName d2, PinName d3, int columns, int rows) : _rw(rw), _rs(rs), 
+	_e(e), _d(d0, d1, d2, d3), _columns(columns), _rows(rows) {
+
+//	_rows = 2;
+//	_columns = 16;
+	// Mon, 27 Apr 2009 23:32:34 +0200
+	// Kevin Konradt:
+	// When using a LCD with 1 row x 16 characters
+	// instead of 2x16, try changing _columns to 8.
+	// (display seems to split the 16 characters into 
+	// 2 virtual rows with 8 characters each.)
+
+	_rw = 0;
+	_e  = 1;
+	_rs = 0; // command mode
+
+	// Should theoretically wait 15ms, but most things will be powered up pre-reset
+	// so i'll disable that for the minute. If implemented, could wait 15ms post reset
+	// instead
+	// wait(0.015); 
+		
+	// send "Display Settings" 3 times (Only top nibble of 0x30 as we've got 4-bit bus)
+	for(int i=0; i<3; i++) {
+		writeNibble(0x3);
+		wait(0.00164);      // this command takes 1.64ms, so wait for it
+	}
+	writeNibble(0x2); // 4-bit mode
+			
+	writeCommand(0x28);    // Function set 001 BW N F - -  
+	writeCommand(0x0C);
+	writeCommand(0x6);  //  Cursor Direction and Display Shift : 0000 01 CD S (CD 0-left, 1-right S(hift) 0-no, 1-yes
+	
+	cls();
+}
+
+int TextLCD::_putc(int value) {
+	if(value == '\n') {
+		newline();
+	} else {
+		writeData(value);
+	}
+	return value;
+}
+
+int TextLCD::_getc() {
+	return 0;
+}
+
+void TextLCD::newline() {
+	_column = 0;
+	_row++;
+	if(_row >= _rows) {
+		_row = 0;
+	}
+	locate(_column, _row); 
+}
+
+void TextLCD::locate(int column, int row) {
+	if(column < 0 || column >= _columns || row < 0 || row >= _rows) {
+		error("locate(%d,%d) out of range on %dx%d display", column, row, _columns, _rows);
+		return;
+	}
+	
+	_row = row;
+  	_column = column;
+  	int address = 0x80 + (_row * 40) + _column; // memory starts at 0x80, and is 40 chars long per row
+  	writeCommand(address);            
+}
+
+void TextLCD::cls() {
+	writeCommand(0x01); // Clear Display
+	wait(0.00164f);		// This command takes 1.64 ms
+  	locate(0, 0);
+}
+
+void TextLCD::reset() {
+	cls();
+}
+
+void TextLCD::clock() {
+	wait(0.000040f);
+	_e = 0;
+	wait(0.000040f);  // most instructions take 40us
+	_e = 1;	
+}
+
+void TextLCD::writeNibble(int value) {
+	_d = value;
+	clock();
+}
+
+void TextLCD::writeByte(int value) {
+	writeNibble(value >> 4);
+	writeNibble(value >> 0);
+}
+
+void TextLCD::writeCommand(int command) {
+	_rs = 0;
+	writeByte(command);
+}
+
+void TextLCD::writeData(int data) {
+	_rs = 1;
+	writeByte(data);
+	_column++;
+	if(_column >= _columns) {
+		newline();
+	} 
+}