Diff: TextLCD.cpp

Revision:

0:6beb6f498640

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/TextLCD.cpp	Mon Aug 09 14:17:02 2010 +0000
@@ -0,0 +1,193 @@
+/* mbed I2CTextLCD Library, for a 4-bit LCD driven by I2C and a PCF8574
+ * Copyright (c) 2007-2010, sford, rcocking
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+/* This is a hack of Simon Ford's direct-driven TextLCD code.
+* It should be refactored to extract a common superclass
+* but my C++ isn't yet good enough :) 
+*
+* The code assumes the following connections between the PCF8574
+* and the LCD
+* 
+* nc  - D0
+* nc  - D1
+* nc  - D2
+* nc  - D3
+* P0  - D4
+* P1  - D5
+* P2  - D6
+* P3  - D7
+* P4  - E
+* P5  - nc
+* P6  - nc
+* P7  - RS
+* gnd - R/W
+*
+* D0-3 of the LCD are not connected because we work in 4-bit mode
+* R/W is hardwired to gound, as we only ever write to the LCD
+* A0-2 on the PCF8574 can be set in any combination; you will need to modify
+* the I2C address in the I2CTextLCD constructor.
+* Remember that the mbed uses 8-bit addresses, which should be
+* in the range 0x40-0x4E for the PCF8574
+*/
+#include "TextLCD.h"
+#include "mbed.h"
+
+TextLCD::TextLCD(PinName sda, PinName scl, int i2cAddress, LCDType type) : _i2c(sda, scl),
+        _type(type) {
+    _i2cAddress = i2cAddress;
+    wait(0.015);        // Wait 15ms to ensure powered up
+
+    // send "Display Settings" 3 times (Only top nibble of 0x30 as we've got 4-bit bus)
+    for (int i=0; i<3; i++) {
+        writeByte(0x3, false);
+        wait(0.00164);  // this command takes 1.64ms, so wait for it
+    }
+    writeByte(0x2, false);     // 4-bit mode
+    wait(0.000040f);    // most instructions take 40us
+
+    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();
+}
+
+void TextLCD::character(int column, int row, int c) {
+    int a = address(column, row);
+    writeCommand(a);
+    writeData(c);
+}
+
+void TextLCD::cls() {
+    writeCommand(0x01); // cls, and set cursor to 0
+    wait(0.00164f);     // This command takes 1.64 ms
+    locate(0, 0);
+}
+
+void TextLCD::locate(int column, int row) {
+    _column = column;
+    _row = row;
+}
+
+int TextLCD::_putc(int value) {
+    if (value == '\n') {
+        _column = 0;
+        _row++;
+        if (_row >= rows()) {
+            _row = 0;
+        }
+    } else {
+        character(_column, _row, value);
+        _column++;
+        if (_column >= columns()) {
+            _column = 0;
+            _row++;
+            if (_row >= rows()) {
+                _row = 0;
+            }
+        }
+    }
+    return value;
+}
+
+int TextLCD::_getc() {
+    return -1;
+}
+
+void TextLCD::writeI2CByte(int data) {
+    // equivalent to writeI2CByte
+    char * cmd = new char[1];
+    cmd[0] = data;
+    _i2c.write(_i2cAddress, cmd, 1);
+}
+
+void TextLCD::writeNibble(int data, bool rs) {
+    if (rs) {
+        data = data | RS_ON; // set rs bit
+    }
+    data |= E_ON; // E on
+    writeI2CByte(data);
+    data ^= E_ON; // E off
+    wait_us(1);
+    writeI2CByte(data);
+    wait_us(1000);
+}
+
+void TextLCD::writeByte(int data, bool rs) {
+    writeNibble(data >> 4, rs);
+    writeNibble(data & 0x0F, rs);
+}
+
+void TextLCD::writeCommand(int command) {
+    // equivalent to ard commandWrite
+    writeByte(command, false);
+}
+
+void TextLCD::writeData(int data) {
+
+    writeByte(data, true);
+}
+
+int TextLCD::address(int column, int row) {
+    switch (_type) {
+        case LCD20x4:
+            switch (row) {
+                case 0:
+                    return 0x80 + column;
+                case 1:
+                    return 0xc0 + column;
+                case 2:
+                    return 0x94 + column;
+                case 3:
+                    return 0xd4 + column;
+            }
+        case LCD16x2B:
+            return 0x80 + (row * 40) + column;
+        case LCD16x2:
+        case LCD20x2:
+        default:
+            return 0x80 + (row * 0x40) + column;
+    }
+}
+
+int TextLCD::columns() {
+    switch (_type) {
+        case LCD20x4:
+        case LCD20x2:
+            return 20;
+        case LCD16x2:
+        case LCD16x2B:
+        default:
+            return 16;
+    }
+}
+
+int TextLCD::rows() {
+    switch (_type) {
+        case LCD20x4:
+            return 4;
+        case LCD16x2:
+        case LCD16x2B:
+        case LCD20x2:
+        default:
+            return 2;
+    }
+}