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libraries/hd44780/examples/ioClass/hd44780_I2Cexp/HelloWorld/HelloWorld.ino

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+// vi:ts=4
+// ----------------------------------------------------------------------------
+// HelloWorld - simple demonstration of lcd
+// Created by Bill Perry 2016-07-02
+// bperrybap@opensource.billsworld.billandterrie.com
+//
+// This example code is unlicensed and is released into the public domain
+// ----------------------------------------------------------------------------
+//
+// This sketch is for LCDs with PCF8574 or MCP23008 chip based backpacks
+// WARNING:
+//	Use caution when using 3v only processors like arm and ESP8266 processors
+//	when interfacing with 5v modules as not doing proper level shifting or
+//	incorrectly hooking things up can damage the processor.
+// 
+// Sketch prints "Hello, World!" on the lcd
+//
+// If initialization of the LCD fails and the arduino supports a built in LED,
+// the sketch will simply blink the built in LED.
+//
+// NOTE:
+//	If the sketch fails to produce the expected results, or blinks the LED,
+//	run the included I2CexpDiag sketch to test the i2c signals and the LCD.
+//
+// ----------------------------------------------------------------------------
+// LiquidCrystal compability:
+// Since hd44780 is LiquidCrystal API compatible, most existing LiquidCrystal
+// sketches should work with hd44780 hd44780_I2Cexp i/o class once the
+// includes are changed to use hd44780 and the lcd object constructor is
+// changed to use the hd44780_I2Cexp i/o class.
+
+#include <Wire.h>
+#include <hd44780.h>                       // main hd44780 header
+#include <hd44780ioClass/hd44780_I2Cexp.h> // i2c expander i/o class header
+
+hd44780_I2Cexp lcd; // declare lcd object: auto locate & auto config expander chip
+
+// If you wish to use an i/o expander at a specific address, you can specify the
+// i2c address and let the library auto configure it. If you don't specify
+// the address, or use an address of zero, the library will search for the
+// i2c address of the device.
+// hd44780_I2Cexp lcd(i2c_address); // specify a specific i2c address
+//
+// It is also possible to create multiple/seperate lcd objects
+// and the library can still automatically locate them.
+// Example:
+// hd4480_I2Cexp lcd1;
+// hd4480_I2Cexp lcd2;
+// The individual lcds would be referenced as lcd1 and lcd2
+// i.e. lcd1.home() or lcd2.clear()
+//
+// It is also possible to specify the i2c address
+// when declaring the lcd object.
+// Example:
+// hd44780_I2Cexp lcd1(0x20);
+// hd44780_I2Cexp lcd2(0x27);
+// This ensures that each each lcd object is assigned to a specific
+// lcd device rather than letting the library automatically asign it.
+
+// LCD geometry
+const int LCD_COLS = 16;
+const int LCD_ROWS = 2;
+
+void setup()
+{
+int status;
+
+	// initialize LCD with number of columns and rows: 
+	// hd44780 returns a status from begin() that can be used
+	// to determine if initalization failed.
+	// the actual status codes are defined in <hd44780.h>
+	// See the values RV_XXXX
+	//
+	// looking at the return status from begin() is optional
+	// it is being done here to provide feedback should there be an issue
+	//
+	// note:
+	//	begin() will automatically turn on the backlight
+	//
+	status = lcd.begin(LCD_COLS, LCD_ROWS);
+	if(status) // non zero status means it was unsuccesful
+	{
+		// hd44780 has a fatalError() routine that blinks an led if possible
+		// begin() failed so blink error code using the onboard LED if possible
+		hd44780::fatalError(status); // does not return
+	}
+
+	// initalization was successful, the backlight should be on now
+
+	// Print a message to the LCD
+	lcd.print("Hello, World!");
+}
+
+void loop() {}