Diff: WattBob_TextLCD.cpp

Revision:

0:e5b7c70254ac

Child:

7:020722c18a8b

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/WattBob_TextLCD.cpp	Sun Nov 28 22:47:51 2010 +0000
@@ -0,0 +1,167 @@
+/* draft mbed TextLCD 
+ * (c) 2007/8, sford
+ * Modified jherd
+ */
+ 
+#include "WattBob_TextLCD.h"
+#include "MCP23017.h"
+
+#include "mbed.h"
+
+/*
+ * 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 uses it differently
+ * _rs is set by the data/command writes
+ * 
+ * RS = 7
+ * RW = 6
+ * E  = 5
+ * Back light = 4
+ * D4 = 0
+ * D5 = 1  
+ * D6 = 2
+ * D7 = 3  
+ */
+
+WattBob_TextLCD::WattBob_TextLCD(MCP23017 *port) {
+//
+// Initialise pointer to MCP23017 object
+//
+    par_port = port;
+    par_port->config(0x0F00, 0x0F00, 0x0F00);
+    
+    _rows = 2;
+    _columns = 16;
+
+    _rw(0);
+    _e(0);
+    _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 WattBob_TextLCD::_putc(int value) {
+    if(value == '\n') {
+        newline();
+    } else {
+        writeData(value);
+    }
+    return value;
+}
+
+int WattBob_TextLCD::_getc() {
+    return 0;
+}
+
+void WattBob_TextLCD::newline() {
+    _column = 0;
+    _row++;
+    if(_row >= _rows) {
+        _row = 0;
+    }
+    locate(_column, _row); 
+}
+
+void WattBob_TextLCD::locate(int row, int column) {
+    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 WattBob_TextLCD::cls() {
+    writeCommand(0x01);          // Clear Display
+    wait(0.00164f);              // This command takes 1.64 ms
+      locate(0, 0);
+}
+
+void WattBob_TextLCD::reset() {
+    cls();
+}
+
+void WattBob_TextLCD::clock() {
+    wait(0.000040f);
+    _e(1);
+    wait(0.000040f);  // most instructions take 40us
+    _e(0);    
+}
+
+void WattBob_TextLCD::writeNibble(int value) {
+    _d(value);
+    clock();
+}
+
+void WattBob_TextLCD::writeByte(int value) {
+    writeNibble((value >> 4) & 0x000F);
+    writeNibble((value >> 0) & 0x000F);
+}
+
+void WattBob_TextLCD::writeCommand(int command) {
+    _rs(0);
+    writeByte(command);
+}
+
+void WattBob_TextLCD::writeData(int data) {
+    _rs(1);
+    writeByte(data);
+    _column++;
+    if(_column >= _columns) {
+        newline();
+    } 
+}
+
+void WattBob_TextLCD::_rs(int data) {
+    par_port->write_bit(data, RS_BIT);
+}
+
+void WattBob_TextLCD::_rw(int data) {
+    par_port->write_bit(data, RW_BIT);
+}
+
+void WattBob_TextLCD::_e(int data) {
+    par_port->write_bit(data, E_BIT);
+}
+
+void WattBob_TextLCD::_d(int data) {
+    par_port->write_mask((unsigned short)data, (unsigned short)0x000F);
+}