Add support for Arduino LiquidCrystal LED displays (Hitachi HD44780)

Display_Implementation.h

@@ -30,6 +30,7 @@
 #include "DisplayInterface.h"
 #include "SSD1306Ascii.h"
 #include "LiquidCrystal_I2C.h"
+#include "LiquidCrystal_Parallel.h"
 
 
 // Implement the Display shim class as a singleton.
@@ -38,6 +39,7 @@
 // Then Display class talks to the specific device type classes:
 //    SSD1306AsciiWire for I2C OLED driver with SSD1306 or SH1106 controllers;
 //    LiquidCrystal_I2C for I2C LCD driver for HD44780 with PCF8574 'backpack'.
+//    LiquidCrystal_Parallel for HD44780 in parallel mode.
 
 #if defined(OLED_DRIVER)
   #define DISPLAY_START(xxx) { \
@@ -53,6 +55,14 @@
     t->begin(); \
     xxx;  \
     t->refresh();}
+
+#elif defined(PARALLEL_LCD_DRIVER)
+  #define DISPLAY_START(xxx) { \
+    DisplayInterface *t = new Display( \
+      new LiquidCrystal_Parallel(PARALLEL_LCD_DRIVER)); \
+    t->begin(); \
+    xxx;  \
+    t->refresh();}
 #else
   #define DISPLAY_START(xxx) { \
   xxx; \

LiquidCrystal_Parallel.cpp

@@ -0,0 +1,61 @@
+/*
+ *  © 2024, Oskar Senft. All rights reserved.
+ *
+ *  This file is part of CommandStation-EX
+ *
+ *  This is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  It is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with CommandStation-EX.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include <Arduino.h>
+#include "LiquidCrystal_Parallel.h"
+#include "DIAG.h"
+
+LiquidCrystal_Parallel::LiquidCrystal_Parallel(
+    uint16_t cols, uint16_t rows,
+    uint8_t rs, uint8_t rw, uint8_t enable,
+    uint8_t d4, uint8_t d5, uint8_t d6, uint8_t d7)
+    : _cols(cols), _rows(rows), lcd(rs, rw, enable, d4, d5, d6, d7)
+{
+}
+
+bool LiquidCrystal_Parallel::begin()
+{
+    lcd.begin(getNumCols(), getNumRows());
+    lcd.noCursor();
+    return true;
+}
+
+void LiquidCrystal_Parallel::clearNative()
+{
+    lcd.clear();
+}
+
+void LiquidCrystal_Parallel::setRowNative(byte row)
+{
+    if (row >= getNumRows())
+    {
+        row = getNumRows() - 1; // we count rows starting w/0
+    }
+    lcd.setCursor(0, row);
+}
+
+size_t LiquidCrystal_Parallel::writeNative(uint8_t value)
+{
+    return lcd.write(value);
+}
+
+bool LiquidCrystal_Parallel::isBusy()
+{
+    return false;
+}

LiquidCrystal_Parallel.h

@@ -0,0 +1,69 @@
+/*
+ *  © 2024, Oskar Senft. All rights reserved.
+ *
+ *  This file is part of CommandStation-EX
+ *
+ *  This is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  It is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with CommandStation.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef LiquidCrystal_Parallel_h
+#define LiquidCrystal_Parallel_h
+
+#include <Arduino.h>
+#include "Display.h"
+
+#ifdef PARALLEL_LCD_DRIVER
+// Only use the Arduino library if the driver is actually enabled.
+#include <LiquidCrystal.h>
+#else
+// If the driver is not enabled, use a dummy version instead.
+class LiquidCrystal
+{
+public:
+    LiquidCrystal(uint8_t rs, uint8_t rw, uint8_t enable,
+                  uint8_t d4, uint8_t d5, uint8_t d6, uint8_t d7) {};
+    void begin(uint16_t cols, uint16_t rows) {};
+    void noCursor() {};
+    void setCursor(uint16_t col, uint16_t row) {};
+    void clear() {};
+    size_t write(uint8_t val) { return 0; };
+};
+#endif
+
+// Support for an LCD based on the Hitachi HD44780 (or a compatible) chipset
+// as supported by Arduino's LiquidCrystal library.
+class LiquidCrystal_Parallel : public DisplayDevice
+{
+public:
+    // Specify the display's number of columns and rows as well
+    // as Arduino pins numbers for the display's pins (4-bit mode)
+    LiquidCrystal_Parallel(uint16_t cols, uint16_t rows,
+                           uint8_t rs, uint8_t rw, uint8_t enable,
+                           uint8_t d4, uint8_t d5, uint8_t d6, uint8_t d7);
+    bool begin() override;
+    void clearNative() override;
+    void setRowNative(byte line) override;
+    size_t writeNative(uint8_t c) override;
+    bool isBusy() override;
+
+    uint16_t getNumCols() override { return _cols; }
+    uint16_t getNumRows() override { return _rows; }
+
+private:
+    LiquidCrystal lcd;
+    const uint16_t _cols;
+    const uint16_t _rows;
+};
+
+#endif

config.example.h

@@ -161,6 +161,10 @@ The configuration file for DCC-EX Command Station
 // Use 132,64 for a SH1106-based I2C device with a 128x64 display.
 // #define OLED_DRIVER 0x3c,128,32
 
+//OR define PARALLEL_LCD_DRIVER COLS,ROWS,RS,RW,ENABLE,D4,D5,D6,D7
+// using Arduino pin numbers for RS,RW,ENABLE,D4,D5,D6,D7
+// #define PARALLEL_LCD_DRIVER 20, 4, 26, 27, 28, 22, 23, 24, 25
+
 // Define scroll mode as 0, 1 or 2
 //  *  #define SCROLLMODE 0 is scroll continuous (fill screen if poss),
 //  *  #define SCROLLMODE 1 is by page (alternate between pages),