Diff: TextLCD.cpp
- Revision:
- 0:8e3468376286
diff -r 000000000000 -r 8e3468376286 TextLCD.cpp
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/TextLCD.cpp Sat May 07 12:37:10 2011 +0000
@@ -0,0 +1,180 @@
+/* draft mbed TextLCD
+ * (c) 2007/8, sford
+ */
+
+#include "TextLCD.h"
+
+#include "mbed.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) : _rw(rw), _rs(rs),
+ _e(e), _d(d0, d1, d2, d3){
+
+ _rows = 4;
+ _columns = 20;
+
+ _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=0;
+ // row 0 : 0x0->0x13
+ // row 1 : 0x40->0x53
+ // row 2 : 0x14->0x27
+ // row 3 : 0x54->0x67
+
+ switch (_row) {
+ case (0) : address = 0x00 + _column;
+ break;
+ case (1) : address = 0x40 + _column;
+ break;
+ case (2) : address = 0x14 + _column;
+ break;
+ case (3) : address = 0x54 + _column;
+ break;
+ }
+
+ address += 0x80;
+
+// }
+// else {
+ // memory starts at 0x80, and is 40 chars long per row
+// address = 0x80 + (_row * 40) + _column;
+// }
+
+ writeCommand(address);
+}
+
+
+void TextLCD::rows(int rows) {
+ _rows = rows;
+}
+
+
+void TextLCD::columns(int columns) {
+ _columns = columns;
+}
+
+
+
+
+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();
+ }
+}