commit 3f7c7d9bf3d67c44d4c703323ee57dbb2e1dd587
Author: Gitea <me@unbewohnte.xyz>
Date:   Mon Jul 18 21:25:44 2022 +0300

    Initial commit

diff --git a/LICENSE b/LICENSE
new file mode 100644
index 0000000..073bd06
--- /dev/null
+++ b/LICENSE
@@ -0,0 +1,9 @@
+ The MIT License (MIT)
+
+Copyright © 2022 Kasyanov Nikolay Alexeyevich (Unbewohnte)
+
+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. 
diff --git a/a_really_bad_rangefinder.ino b/a_really_bad_rangefinder.ino
new file mode 100644
index 0000000..dcf3e03
--- /dev/null
+++ b/a_really_bad_rangefinder.ino
@@ -0,0 +1,80 @@
+#include <LiquidCrystal_I2C.h>
+
+/*
+ The MIT License (MIT)
+
+Copyright © 2022 Kasyanov Nikolay Alexeyevich (Unbewohnte)
+
+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.
+*/
+
+bool active = false;
+
+unsigned int trigger_pin = 5;
+unsigned int echo_pin = 6;
+unsigned int button_pin = 13; 
+
+LiquidCrystal_I2C lcd(0x27, 16, 4);
+
+void setup() {
+   Serial.begin(9600);
+   // turn on/off button
+   pinMode(button_pin, INPUT_PULLUP);
+   
+   // ultrasonic sensor
+   pinMode(trigger_pin, OUTPUT);
+   pinMode(echo_pin, INPUT);
+
+   // display is initialized during a mainloop
+}
+
+void loop() {
+  int button_state = digitalRead(button_pin);
+  if (button_state == LOW && !active) {
+    active = true;
+    lcd.init();
+    lcd.backlight();
+    lcd.clear();
+    delay(250);
+  } else if (button_state == LOW && active) {
+    active = false;
+    lcd.noBacklight();
+    lcd.clear();
+    delay(250);
+  }
+
+  if (active) {
+    unsigned int duration, distance_cm;
+    float distance_m;
+    
+    digitalWrite(trigger_pin, LOW);
+    delayMicroseconds(2);
+  
+    // initialize the sensor
+    digitalWrite(trigger_pin, HIGH);
+    delayMicroseconds(10);
+    digitalWrite(trigger_pin, LOW);
+  
+    // get sensor's measurements and calculate distance
+    duration = pulseIn(echo_pin, HIGH);
+    distance_cm = duration / 58;
+    distance_m = (float) distance_cm / 100;
+  
+    // print distance to the screen
+    lcd.clear();
+    lcd.setCursor(0, 0);
+    lcd.print(distance_cm);
+    lcd.print(" cm");
+  
+    lcd.setCursor(8, 0);
+    lcd.print("(");
+    lcd.print(distance_m);
+    lcd.print(" m)");
+    
+    delay(150); 
+  }
+}
diff --git a/lib/LCD_I2C/LICENSE b/lib/LCD_I2C/LICENSE
new file mode 100644
index 0000000..471e45d
--- /dev/null
+++ b/lib/LCD_I2C/LICENSE
@@ -0,0 +1,21 @@
+MIT License
+
+Copyright (c) 2020 Tandembyte
+
+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.
diff --git a/lib/LCD_I2C/LiquidCrystal_I2C.cpp b/lib/LCD_I2C/LiquidCrystal_I2C.cpp
new file mode 100644
index 0000000..9dea08c
--- /dev/null
+++ b/lib/LCD_I2C/LiquidCrystal_I2C.cpp
@@ -0,0 +1,332 @@
+// Based on the work by DFRobot
+
+#include "LiquidCrystal_I2C.h"
+#include <inttypes.h>
+#if defined(ARDUINO) && ARDUINO >= 100
+
+#include "Arduino.h"
+
+#define printIIC(args)	Wire.write(args)
+inline size_t LiquidCrystal_I2C::write(uint8_t value) {
+	send(value, Rs);
+	return 1;
+}
+
+#else
+#include "WProgram.h"
+
+#define printIIC(args)	Wire.send(args)
+inline void LiquidCrystal_I2C::write(uint8_t value) {
+	send(value, Rs);
+}
+
+#endif
+#include "Wire.h"
+
+
+
+// When the display powers up, it is configured as follows:
+//
+// 1. Display clear
+// 2. Function set: 
+//    DL = 1; 8-bit interface data 
+//    N = 0; 1-line display 
+//    F = 0; 5x8 dot character font 
+// 3. Display on/off control: 
+//    D = 0; Display off 
+//    C = 0; Cursor off 
+//    B = 0; Blinking off 
+// 4. Entry mode set: 
+//    I/D = 1; Increment by 1
+//    S = 0; No shift 
+//
+// Note, however, that resetting the Arduino doesn't reset the LCD, so we
+// can't assume that its in that state when a sketch starts (and the
+// LiquidCrystal constructor is called).
+
+LiquidCrystal_I2C::LiquidCrystal_I2C(uint8_t lcd_Addr,uint8_t lcd_cols,uint8_t lcd_rows)
+{
+  _Addr = lcd_Addr;
+  _cols = lcd_cols;
+  _rows = lcd_rows;
+  _backlightval = LCD_NOBACKLIGHT;
+}
+
+void LiquidCrystal_I2C::oled_init(){
+  _oled = true;
+	init_priv();
+}
+
+void LiquidCrystal_I2C::init(){
+	init_priv();
+}
+
+void LiquidCrystal_I2C::init_priv()
+{
+	Wire.begin();
+	_displayfunction = LCD_4BITMODE | LCD_1LINE | LCD_5x8DOTS;
+	begin(_cols, _rows);  
+}
+
+void LiquidCrystal_I2C::begin(uint8_t cols, uint8_t lines, uint8_t dotsize) {
+	if (lines > 1) {
+		_displayfunction |= LCD_2LINE;
+	}
+	_numlines = lines;
+
+	// for some 1 line displays you can select a 10 pixel high font
+	if ((dotsize != 0) && (lines == 1)) {
+		_displayfunction |= LCD_5x10DOTS;
+	}
+
+	// SEE PAGE 45/46 FOR INITIALIZATION SPECIFICATION!
+	// according to datasheet, we need at least 40ms after power rises above 2.7V
+	// before sending commands. Arduino can turn on way befer 4.5V so we'll wait 50
+	delay(50); 
+  
+	// Now we pull both RS and R/W low to begin commands
+	expanderWrite(_backlightval);	// reset expanderand turn backlight off (Bit 8 =1)
+	delay(1000);
+
+  	//put the LCD into 4 bit mode
+	// this is according to the hitachi HD44780 datasheet
+	// figure 24, pg 46
+	
+	  // we start in 8bit mode, try to set 4 bit mode
+   write4bits(0x03 << 4);
+   delayMicroseconds(4500); // wait min 4.1ms
+   
+   // second try
+   write4bits(0x03 << 4);
+   delayMicroseconds(4500); // wait min 4.1ms
+   
+   // third go!
+   write4bits(0x03 << 4); 
+   delayMicroseconds(150);
+   
+   // finally, set to 4-bit interface
+   write4bits(0x02 << 4); 
+
+
+	// set # lines, font size, etc.
+	command(LCD_FUNCTIONSET | _displayfunction);  
+	
+	// turn the display on with no cursor or blinking default
+	_displaycontrol = LCD_DISPLAYON | LCD_CURSOROFF | LCD_BLINKOFF;
+	display();
+	
+	// clear it off
+	clear();
+	
+	// Initialize to default text direction (for roman languages)
+	_displaymode = LCD_ENTRYLEFT | LCD_ENTRYSHIFTDECREMENT;
+	
+	// set the entry mode
+	command(LCD_ENTRYMODESET | _displaymode);
+	
+	home();
+  
+}
+
+/********** high level commands, for the user! */
+void LiquidCrystal_I2C::clear(){
+	command(LCD_CLEARDISPLAY);// clear display, set cursor position to zero
+	delayMicroseconds(2000);  // this command takes a long time!
+  if (_oled) setCursor(0,0);
+}
+
+void LiquidCrystal_I2C::home(){
+	command(LCD_RETURNHOME);  // set cursor position to zero
+	delayMicroseconds(2000);  // this command takes a long time!
+}
+
+void LiquidCrystal_I2C::setCursor(uint8_t col, uint8_t row){
+	int row_offsets[] = { 0x00, 0x40, 0x14, 0x54 };
+	if ( row > _numlines ) {
+		row = _numlines-1;    // we count rows starting w/0
+	}
+	command(LCD_SETDDRAMADDR | (col + row_offsets[row]));
+}
+
+// Turn the display on/off (quickly)
+void LiquidCrystal_I2C::noDisplay() {
+	_displaycontrol &= ~LCD_DISPLAYON;
+	command(LCD_DISPLAYCONTROL | _displaycontrol);
+}
+void LiquidCrystal_I2C::display() {
+	_displaycontrol |= LCD_DISPLAYON;
+	command(LCD_DISPLAYCONTROL | _displaycontrol);
+}
+
+// Turns the underline cursor on/off
+void LiquidCrystal_I2C::noCursor() {
+	_displaycontrol &= ~LCD_CURSORON;
+	command(LCD_DISPLAYCONTROL | _displaycontrol);
+}
+void LiquidCrystal_I2C::cursor() {
+	_displaycontrol |= LCD_CURSORON;
+	command(LCD_DISPLAYCONTROL | _displaycontrol);
+}
+
+// Turn on and off the blinking cursor
+void LiquidCrystal_I2C::noBlink() {
+	_displaycontrol &= ~LCD_BLINKON;
+	command(LCD_DISPLAYCONTROL | _displaycontrol);
+}
+void LiquidCrystal_I2C::blink() {
+	_displaycontrol |= LCD_BLINKON;
+	command(LCD_DISPLAYCONTROL | _displaycontrol);
+}
+
+// These commands scroll the display without changing the RAM
+void LiquidCrystal_I2C::scrollDisplayLeft(void) {
+	command(LCD_CURSORSHIFT | LCD_DISPLAYMOVE | LCD_MOVELEFT);
+}
+void LiquidCrystal_I2C::scrollDisplayRight(void) {
+	command(LCD_CURSORSHIFT | LCD_DISPLAYMOVE | LCD_MOVERIGHT);
+}
+
+// This is for text that flows Left to Right
+void LiquidCrystal_I2C::leftToRight(void) {
+	_displaymode |= LCD_ENTRYLEFT;
+	command(LCD_ENTRYMODESET | _displaymode);
+}
+
+// This is for text that flows Right to Left
+void LiquidCrystal_I2C::rightToLeft(void) {
+	_displaymode &= ~LCD_ENTRYLEFT;
+	command(LCD_ENTRYMODESET | _displaymode);
+}
+
+// This will 'right justify' text from the cursor
+void LiquidCrystal_I2C::autoscroll(void) {
+	_displaymode |= LCD_ENTRYSHIFTINCREMENT;
+	command(LCD_ENTRYMODESET | _displaymode);
+}
+
+// This will 'left justify' text from the cursor
+void LiquidCrystal_I2C::noAutoscroll(void) {
+	_displaymode &= ~LCD_ENTRYSHIFTINCREMENT;
+	command(LCD_ENTRYMODESET | _displaymode);
+}
+
+// Allows us to fill the first 8 CGRAM locations
+// with custom characters
+void LiquidCrystal_I2C::createChar(uint8_t location, uint8_t charmap[]) {
+	location &= 0x7; // we only have 8 locations 0-7
+	command(LCD_SETCGRAMADDR | (location << 3));
+	for (int i=0; i<8; i++) {
+		write(charmap[i]);
+	}
+}
+
+//createChar with PROGMEM input
+void LiquidCrystal_I2C::createChar(uint8_t location, const char *charmap) {
+	location &= 0x7; // we only have 8 locations 0-7
+	command(LCD_SETCGRAMADDR | (location << 3));
+	for (int i=0; i<8; i++) {
+	    	write(pgm_read_byte_near(charmap++));
+	}
+}
+
+// Turn the (optional) backlight off/on
+void LiquidCrystal_I2C::noBacklight(void) {
+	_backlightval=LCD_NOBACKLIGHT;
+	expanderWrite(0);
+}
+
+void LiquidCrystal_I2C::backlight(void) {
+	_backlightval=LCD_BACKLIGHT;
+	expanderWrite(0);
+}
+
+
+
+/*********** mid level commands, for sending data/cmds */
+
+inline void LiquidCrystal_I2C::command(uint8_t value) {
+	send(value, 0);
+}
+
+
+/************ low level data pushing commands **********/
+
+// write either command or data
+void LiquidCrystal_I2C::send(uint8_t value, uint8_t mode) {
+	uint8_t highnib=value&0xf0;
+	uint8_t lownib=(value<<4)&0xf0;
+       write4bits((highnib)|mode);
+	write4bits((lownib)|mode); 
+}
+
+void LiquidCrystal_I2C::write4bits(uint8_t value) {
+	expanderWrite(value);
+	pulseEnable(value);
+}
+
+void LiquidCrystal_I2C::expanderWrite(uint8_t _data){                                        
+	Wire.beginTransmission(_Addr);
+	printIIC((int)(_data) | _backlightval);
+	Wire.endTransmission();   
+}
+
+void LiquidCrystal_I2C::pulseEnable(uint8_t _data){
+	expanderWrite(_data | En);	// En high
+	delayMicroseconds(1);		// enable pulse must be >450ns
+	
+	expanderWrite(_data & ~En);	// En low
+	delayMicroseconds(50);		// commands need > 37us to settle
+} 
+
+
+// Alias functions
+
+void LiquidCrystal_I2C::cursor_on(){
+	cursor();
+}
+
+void LiquidCrystal_I2C::cursor_off(){
+	noCursor();
+}
+
+void LiquidCrystal_I2C::blink_on(){
+	blink();
+}
+
+void LiquidCrystal_I2C::blink_off(){
+	noBlink();
+}
+
+void LiquidCrystal_I2C::load_custom_character(uint8_t char_num, uint8_t *rows){
+		createChar(char_num, rows);
+}
+
+void LiquidCrystal_I2C::setBacklight(uint8_t new_val){
+	if(new_val){
+		backlight();		// turn backlight on
+	}else{
+		noBacklight();		// turn backlight off
+	}
+}
+
+void LiquidCrystal_I2C::printstr(const char c[]){
+	//This function is not identical to the function used for "real" I2C displays
+	//it's here so the user sketch doesn't have to be changed 
+	print(c);
+}
+
+
+// unsupported API functions
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wunused-parameter"
+void LiquidCrystal_I2C::off(){}
+void LiquidCrystal_I2C::on(){}
+void LiquidCrystal_I2C::setDelay (int cmdDelay,int charDelay) {}
+uint8_t LiquidCrystal_I2C::status(){return 0;}
+uint8_t LiquidCrystal_I2C::keypad (){return 0;}
+uint8_t LiquidCrystal_I2C::init_bargraph(uint8_t graphtype){return 0;}
+void LiquidCrystal_I2C::draw_horizontal_graph(uint8_t row, uint8_t column, uint8_t len,  uint8_t pixel_col_end){}
+void LiquidCrystal_I2C::draw_vertical_graph(uint8_t row, uint8_t column, uint8_t len,  uint8_t pixel_row_end){}
+void LiquidCrystal_I2C::setContrast(uint8_t new_val){}
+#pragma GCC diagnostic pop
+	
diff --git a/lib/LCD_I2C/LiquidCrystal_I2C.h b/lib/LCD_I2C/LiquidCrystal_I2C.h
new file mode 100644
index 0000000..f7c7d13
--- /dev/null
+++ b/lib/LCD_I2C/LiquidCrystal_I2C.h
@@ -0,0 +1,131 @@
+//YWROBOT
+#ifndef LiquidCrystal_I2C_h
+#define LiquidCrystal_I2C_h
+
+#include <inttypes.h>
+#include "Print.h" 
+#include <Wire.h>
+
+// commands
+#define LCD_CLEARDISPLAY 0x01
+#define LCD_RETURNHOME 0x02
+#define LCD_ENTRYMODESET 0x04
+#define LCD_DISPLAYCONTROL 0x08
+#define LCD_CURSORSHIFT 0x10
+#define LCD_FUNCTIONSET 0x20
+#define LCD_SETCGRAMADDR 0x40
+#define LCD_SETDDRAMADDR 0x80
+
+// flags for display entry mode
+#define LCD_ENTRYRIGHT 0x00
+#define LCD_ENTRYLEFT 0x02
+#define LCD_ENTRYSHIFTINCREMENT 0x01
+#define LCD_ENTRYSHIFTDECREMENT 0x00
+
+// flags for display on/off control
+#define LCD_DISPLAYON 0x04
+#define LCD_DISPLAYOFF 0x00
+#define LCD_CURSORON 0x02
+#define LCD_CURSOROFF 0x00
+#define LCD_BLINKON 0x01
+#define LCD_BLINKOFF 0x00
+
+// flags for display/cursor shift
+#define LCD_DISPLAYMOVE 0x08
+#define LCD_CURSORMOVE 0x00
+#define LCD_MOVERIGHT 0x04
+#define LCD_MOVELEFT 0x00
+
+// flags for function set
+#define LCD_8BITMODE 0x10
+#define LCD_4BITMODE 0x00
+#define LCD_2LINE 0x08
+#define LCD_1LINE 0x00
+#define LCD_5x10DOTS 0x04
+#define LCD_5x8DOTS 0x00
+
+// flags for backlight control
+#define LCD_BACKLIGHT 0x08
+#define LCD_NOBACKLIGHT 0x00
+
+#define En B00000100  // Enable bit
+#define Rw B00000010  // Read/Write bit
+#define Rs B00000001  // Register select bit
+
+class LiquidCrystal_I2C : public Print {
+public:
+  LiquidCrystal_I2C(uint8_t lcd_Addr,uint8_t lcd_cols,uint8_t lcd_rows);
+  void begin(uint8_t cols, uint8_t rows, uint8_t charsize = LCD_5x8DOTS );
+  void clear();
+  void home();
+  void noDisplay();
+  void display();
+  void noBlink();
+  void blink();
+  void noCursor();
+  void cursor();
+  void scrollDisplayLeft();
+  void scrollDisplayRight();
+  void printLeft();
+  void printRight();
+  void leftToRight();
+  void rightToLeft();
+  void shiftIncrement();
+  void shiftDecrement();
+  void noBacklight();
+  void backlight();
+  void autoscroll();
+  void noAutoscroll(); 
+  void createChar(uint8_t, uint8_t[]);
+  void createChar(uint8_t location, const char *charmap);
+  // Example: 	const char bell[8] PROGMEM = {B00100,B01110,B01110,B01110,B11111,B00000,B00100,B00000};
+  
+  void setCursor(uint8_t, uint8_t); 
+#if defined(ARDUINO) && ARDUINO >= 100
+  virtual size_t write(uint8_t);
+#else
+  virtual void write(uint8_t);
+#endif
+  void command(uint8_t);
+  void init();
+  void oled_init();
+
+////compatibility API function aliases
+void blink_on();						// alias for blink()
+void blink_off();       					// alias for noBlink()
+void cursor_on();      	 					// alias for cursor()
+void cursor_off();      					// alias for noCursor()
+void setBacklight(uint8_t new_val);				// alias for backlight() and nobacklight()
+void load_custom_character(uint8_t char_num, uint8_t *rows);	// alias for createChar()
+void printstr(const char[]);
+
+////Unsupported API functions (not implemented in this library)
+uint8_t status();
+void setContrast(uint8_t new_val);
+uint8_t keypad();
+void setDelay(int,int);
+void on();
+void off();
+uint8_t init_bargraph(uint8_t graphtype);
+void draw_horizontal_graph(uint8_t row, uint8_t column, uint8_t len,  uint8_t pixel_col_end);
+void draw_vertical_graph(uint8_t row, uint8_t column, uint8_t len,  uint8_t pixel_col_end);
+	 
+
+private:
+  void init_priv();
+  void send(uint8_t, uint8_t);
+  void write4bits(uint8_t);
+  void expanderWrite(uint8_t);
+  void pulseEnable(uint8_t);
+  uint8_t _Addr;
+  uint8_t _displayfunction;
+  uint8_t _displaycontrol;
+  uint8_t _displaymode;
+  uint8_t _numlines;
+  bool _oled = false;
+  uint8_t _cols;
+  uint8_t _rows;
+  uint8_t _backlightval;
+};
+
+#endif
diff --git a/lib/LCD_I2C/README.md b/lib/LCD_I2C/README.md
new file mode 100644
index 0000000..77b8927
--- /dev/null
+++ b/lib/LCD_I2C/README.md
@@ -0,0 +1,4 @@
+# LCD_I2C
+
+LiquidCrystal Arduino library for I2C LCD displays
+
diff --git a/lib/LCD_I2C/examples/CustomChars/CustomChars.pde b/lib/LCD_I2C/examples/CustomChars/CustomChars.pde
new file mode 100644
index 0000000..e341000
--- /dev/null
+++ b/lib/LCD_I2C/examples/CustomChars/CustomChars.pde
@@ -0,0 +1,70 @@
+//YWROBOT
+//Compatible with the Arduino IDE 1.0
+//Library version:1.1
+#include <Wire.h>
+#include <LiquidCrystal_I2C.h>
+
+#if defined(ARDUINO) && ARDUINO >= 100
+#define printByte(args)  write(args);
+#else
+#define printByte(args)  print(args,BYTE);
+#endif
+
+uint8_t bell[8]  = {0x4,0xe,0xe,0xe,0x1f,0x0,0x4};
+uint8_t note[8]  = {0x2,0x3,0x2,0xe,0x1e,0xc,0x0};
+uint8_t clock[8] = {0x0,0xe,0x15,0x17,0x11,0xe,0x0};
+uint8_t heart[8] = {0x0,0xa,0x1f,0x1f,0xe,0x4,0x0};
+uint8_t duck[8]  = {0x0,0xc,0x1d,0xf,0xf,0x6,0x0};
+uint8_t check[8] = {0x0,0x1,0x3,0x16,0x1c,0x8,0x0};
+uint8_t cross[8] = {0x0,0x1b,0xe,0x4,0xe,0x1b,0x0};
+uint8_t retarrow[8] = {	0x1,0x1,0x5,0x9,0x1f,0x8,0x4};
+  
+LiquidCrystal_I2C lcd(0x27,20,4);  // set the LCD address to 0x27 for a 16 chars and 2 line display
+
+void setup()
+{
+  lcd.init();                      // initialize the lcd 
+  lcd.backlight();
+  
+  lcd.createChar(0, bell);
+  lcd.createChar(1, note);
+  lcd.createChar(2, clock);
+  lcd.createChar(3, heart);
+  lcd.createChar(4, duck);
+  lcd.createChar(5, check);
+  lcd.createChar(6, cross);
+  lcd.createChar(7, retarrow);
+  lcd.home();
+  
+  lcd.print("Hello world...");
+  lcd.setCursor(0, 1);
+  lcd.print(" i ");
+  lcd.printByte(3);
+  lcd.print(" arduinos!");
+  delay(5000);
+  displayKeyCodes();
+  
+}
+
+// display all keycodes
+void displayKeyCodes(void) {
+  uint8_t i = 0;
+  while (1) {
+    lcd.clear();
+    lcd.print("Codes 0x"); lcd.print(i, HEX);
+    lcd.print("-0x"); lcd.print(i+15, HEX);
+    lcd.setCursor(0, 1);
+    for (int j=0; j<16; j++) {
+      lcd.printByte(i+j);
+    }
+    i+=16;
+    
+    delay(4000);
+  }
+}
+
+void loop()
+{
+
+}
+
diff --git a/lib/LCD_I2C/examples/HelloWorld/HelloWorld.pde b/lib/LCD_I2C/examples/HelloWorld/HelloWorld.pde
new file mode 100644
index 0000000..234d115
--- /dev/null
+++ b/lib/LCD_I2C/examples/HelloWorld/HelloWorld.pde
@@ -0,0 +1,26 @@
+//YWROBOT
+//Compatible with the Arduino IDE 1.0
+//Library version:1.1
+#include <LiquidCrystal_I2C.h>
+
+LiquidCrystal_I2C lcd(0x27,20,4);  // set the LCD address to 0x27 for a 16 chars and 2 line display
+
+void setup()
+{
+  lcd.init();                      // initialize the lcd 
+  // Print a message to the LCD.
+  lcd.backlight();
+  lcd.setCursor(3,0);
+  lcd.print("Hello, world!");
+  lcd.setCursor(2,1);
+  lcd.print("Ywrobot Arduino!");
+   lcd.setCursor(0,2);
+  lcd.print("Arduino LCM IIC 2004");
+   lcd.setCursor(2,3);
+  lcd.print("Power By Ec-yuan!");
+}
+
+
+void loop()
+{
+}
diff --git a/lib/LCD_I2C/examples/SerialDisplay/SerialDisplay.pde b/lib/LCD_I2C/examples/SerialDisplay/SerialDisplay.pde
new file mode 100644
index 0000000..1fca4e1
--- /dev/null
+++ b/lib/LCD_I2C/examples/SerialDisplay/SerialDisplay.pde
@@ -0,0 +1,34 @@
+/*
+ * Displays text sent over the serial port (e.g. from the Serial Monitor) on
+ * an attached LCD.
+ * YWROBOT
+ *Compatible with the Arduino IDE 1.0
+ *Library version:1.1
+ */
+#include <Wire.h> 
+#include <LiquidCrystal_I2C.h>
+
+LiquidCrystal_I2C lcd(0x27,20,4);  // set the LCD address to 0x27 for a 16 chars and 2 line display
+
+void setup()
+{
+  lcd.init();                      // initialize the lcd 
+  lcd.backlight();
+  Serial.begin(9600);
+}
+
+void loop()
+{
+  // when characters arrive over the serial port...
+  if (Serial.available()) {
+    // wait a bit for the entire message to arrive
+    delay(100);
+    // clear the screen
+    lcd.clear();
+    // read all the available characters
+    while (Serial.available() > 0) {
+      // display each character to the LCD
+      lcd.write(Serial.read());
+    }
+  }
+}
diff --git a/lib/LCD_I2C/keywords.txt b/lib/LCD_I2C/keywords.txt
new file mode 100644
index 0000000..8c450a9
--- /dev/null
+++ b/lib/LCD_I2C/keywords.txt
@@ -0,0 +1,46 @@
+###########################################
+# Syntax Coloring Map For LiquidCrystal_I2C
+###########################################
+
+###########################################
+# Datatypes (KEYWORD1)
+###########################################
+
+LiquidCrystal_I2C	KEYWORD1
+
+###########################################
+# Methods and Functions (KEYWORD2)
+###########################################
+init	KEYWORD2
+begin	KEYWORD2
+clear	KEYWORD2
+home	KEYWORD2
+noDisplay	KEYWORD2
+display	KEYWORD2
+noBlink	KEYWORD2
+blink	KEYWORD2
+noCursor	KEYWORD2
+cursor	KEYWORD2
+scrollDisplayLeft	KEYWORD2
+scrollDisplayRight	KEYWORD2
+leftToRight	KEYWORD2
+rightToLeft	KEYWORD2
+shiftIncrement	KEYWORD2
+shiftDecrement	KEYWORD2
+noBacklight	KEYWORD2
+backlight	KEYWORD2
+autoscroll	KEYWORD2
+noAutoscroll	KEYWORD2
+createChar	KEYWORD2
+setCursor	KEYWORD2
+print	KEYWORD2
+blink_on	KEYWORD2
+blink_off	KEYWORD2
+cursor_on	KEYWORD2
+cursor_off	KEYWORD2
+setBacklight	KEYWORD2
+load_custom_character	KEYWORD2
+printstr	KEYWORD2
+###########################################
+# Constants (LITERAL1)
+###########################################
diff --git a/lib/LCD_I2C/library.json b/lib/LCD_I2C/library.json
new file mode 100644
index 0000000..4710920
--- /dev/null
+++ b/lib/LCD_I2C/library.json
@@ -0,0 +1,16 @@
+{
+  "name": "LiquidCrystal_I2C",
+  "keywords": "LCD, liquidcrystal, I2C",
+  "description": "A library for DFRobot I2C LCD displays",
+  "repository":
+  {
+    "type": "git",
+    "url": "https://github.com/marcoschwartz/LiquidCrystal_I2C.git"
+  },
+  "frameworks": "arduino",
+  "platforms":
+  [
+    "atmelavr",
+    "espressif8266"
+  ]
+}
diff --git a/lib/LCD_I2C/library.properties b/lib/LCD_I2C/library.properties
new file mode 100644
index 0000000..9764810
--- /dev/null
+++ b/lib/LCD_I2C/library.properties
@@ -0,0 +1,9 @@
+name=LiquidCrystal_I2C
+version=1.1.4
+author=Frank de Brabander
+maintainer=Marco Schwartz <marcolivier.schwartz@gmail.com>
+sentence=A library for I2C LCD displays.
+paragraph= The library allows to control I2C displays with functions extremely similar to LiquidCrystal library. THIS LIBRARY MIGHT NOT BE COMPATIBLE WITH EXISTING SKETCHES.
+category=Display
+url=https://github.com/marcoschwartz/LiquidCrystal_I2C
+architectures=avr
diff --git a/schematics.png b/schematics.png
new file mode 100644
index 0000000..c19bad9
Binary files /dev/null and b/schematics.png differ