Wim Huiskamp / TextLCD

Updated for more display types. Fixed memoryaddress confusion in address() method. Added new getAddress() method. Added support for UDCs, Backlight control and other features such as control through I2C and SPI port expanders and controllers with native I2C and SPI interfaces. Refactored to fix issue with pins that are default declared as NC.

Dependents:   GPSDevice TestTextLCD SD to Flash Data Transfer DrumMachine ... more

Fork of TextLCD by Simon Ford

Example

Hello World! for the TextLCD

#include "mbed.h"
#include "TextLCD.h"
 
// Host PC Communication channels
Serial pc(USBTX, USBRX); // tx, rx
 
// I2C Communication
I2C i2c_lcd(p28,p27); // SDA, SCL
 
// SPI Communication
SPI spi_lcd(p5, NC, p7); // MOSI, MISO, SCLK

//TextLCD lcd(p15, p16, p17, p18, p19, p20);                // RS, E, D4-D7, LCDType=LCD16x2, BL=NC, E2=NC, LCDTCtrl=HD44780
//TextLCD_SPI lcd(&spi_lcd, p8, TextLCD::LCD40x4);   // SPI bus, 74595 expander, CS pin, LCD Type  
TextLCD_I2C lcd(&i2c_lcd, 0x42, TextLCD::LCD20x4);  // I2C bus, PCF8574 Slaveaddress, LCD Type
//TextLCD_I2C lcd(&i2c_lcd, 0x42, TextLCD::LCD16x2, TextLCD::WS0010); // I2C bus, PCF8574 Slaveaddress, LCD Type, Device Type
//TextLCD_SPI_N lcd(&spi_lcd, p8, p9);               // SPI bus, CS pin, RS pin, LCDType=LCD16x2, BL=NC, LCDTCtrl=ST7032_3V3   
//TextLCD_I2C_N lcd(&i2c_lcd, ST7032_SA, TextLCD::LCD16x2, NC, TextLCD::ST7032_3V3); // I2C bus, Slaveaddress, LCD Type, BL=NC, LCDTCtrl=ST7032_3V3  

int main() {
    pc.printf("LCD Test. Columns=%d, Rows=%d\n\r", lcd.columns(), lcd.rows());
    
    for (int row=0; row<lcd.rows(); row++) {
      int col=0;
      
      pc.printf("MemAddr(Col=%d, Row=%d)=0x%02X\n\r", col, row, lcd.getAddress(col, row));      
//      lcd.putc('-');
      lcd.putc('0' + row);      
      
      for (col=1; col<lcd.columns()-1; col++) {    
        lcd.putc('*');
      }
 
      pc.printf("MemAddr(Col=%d, Row=%d)=0x%02X\n\r", col, row, lcd.getAddress(col, row));      
      lcd.putc('+');
        
    }    
    
// Show cursor as blinking character
    lcd.setCursor(TextLCD::CurOff_BlkOn);
 
// Set and show user defined characters. A maximum of 8 UDCs are supported by the HD44780.
// They are defined by a 5x7 bitpattern. 
    lcd.setUDC(0, (char *) udc_0);  // Show |>
    lcd.putc(0);    
    lcd.setUDC(1, (char *) udc_1);  // Show <|
    lcd.putc(1);    

}

Handbook page

More info is here

Diff: TextLCD.cpp

Revision:
8:03116f75b66e
Parent:
7:44f34c09bd37
Child:
9:0893d986e717
--- a/TextLCD.cpp	Sat Dec 04 11:29:57 2010 +0000
+++ b/TextLCD.cpp	Tue Jan 29 20:49:33 2013 +0000
@@ -1,5 +1,6 @@
 /* mbed TextLCD Library, for a 4-bit LCD based on HD44780
  * Copyright (c) 2007-2010, sford, http://mbed.org
+ *               2013, WH, Updated LCD types and fixed lcd address issues
  *
  * Permission is hereby granted, free of charge, to any person obtaining a copy
  * of this software and associated documentation files (the "Software"), to deal
@@ -43,16 +44,19 @@
 
     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
+    writeCommand(0x06); // 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);
+    int addr = getAddress(column, row);
+    
+    writeCommand(0x80 | addr);
     writeData(c);
 }
 
+
 void TextLCD::cls() {
     writeCommand(0x01); // cls, and set cursor to 0
     wait(0.00164f);     // This command takes 1.64 ms
@@ -112,6 +116,12 @@
     writeByte(data);
 }
 
+
+#if (0)
+// This is the original method.
+// It is confusing since it returns the memoryaddress or-ed with the set memorycommand 0x80.
+// Left it in here for compatibility with older code. New applications should use getAddress() instead.
+// 
 int TextLCD::address(int column, int row) {
     switch (_type) {
         case LCD20x4:
@@ -133,27 +143,116 @@
             return 0x80 + (row * 0x40) + column;
     }
 }
+#endif
+
+
+// This replaces the original method.
+// Left it in here for compatibility with older code. New applications should use getAddress() instead.
+int TextLCD::address(int column, int row) {
+  return 0x80 | getAddress(column, row);
+}
+
+// This is new method to return the memory address based on row, column and displaytype.
+//
+int TextLCD::getAddress(int column, int row) {
+
+    switch (_type) {
+        case LCD8x1:
+            return 0x00 + column;                        
+    
+        case LCD16x4:
+            switch (row) {
+                case 0:
+                    return 0x00 + column;
+                case 1:
+                    return 0x40 + column;
+                case 2:
+                    return 0x10 + column;
+                case 3:
+                    return 0x50 + column;
+            }
+
+        case LCD20x4:
+            switch (row) {
+                case 0:
+                    return 0x00 + column;
+                case 1:
+                    return 0x40 + column;
+                case 2:
+                    return 0x14 + column;
+                case 3:
+                    return 0x54 + column;
+            }
+
+// Not sure about this one, seems wrong.
+        case LCD16x2B:      
+            return 0x00 + (row * 40) + column;
+      
+        case LCD8x2:        
+        case LCD16x2:
+        case LCD20x2:
+        case LCD24x2:        
+            return 0x00 + (row * 0x40) + column;
+            
+// Should never get here.
+        default:            
+            return 0x00;        
+    }
+}
+
+
+// Added for consistency. Set row, colum and update memoryaddress.
+//
+void TextLCD::setAddress(int column, int row) {
+
+    locate(column, row);
+    
+    int addr = getAddress(column, row);
+    
+    writeCommand(0x80 | addr);
+}
 
 int TextLCD::columns() {
     switch (_type) {
-        case LCD20x4:
-        case LCD20x2:
-            return 20;
+        case LCD8x1:
+        case LCD8x2:
+            return 8;
+
         case LCD16x2:
         case LCD16x2B:
+        case LCD16x4:        
+            return 16;
+            
+        case LCD20x2:
+        case LCD20x4:
+            return 20;
+
+        case LCD24x2:
+            return 24;        
+        
+// Should never get here.
         default:
-            return 16;
+            return 0;
     }
 }
 
 int TextLCD::rows() {
     switch (_type) {
-        case LCD20x4:
-            return 4;
+        case LCD8x1: 
+            return 1;           
+
+        case LCD8x2:        
         case LCD16x2:
         case LCD16x2B:
         case LCD20x2:
+        case LCD24x2:        
+            return 2;
+                    
+        case LCD16x4:
+        case LCD20x4:
+            return 4;
+      
         default:
-            return 2;
+            return 0;        
     }
 }