Sterowanie wyświetlaczem 4x20 I2C

#include<Wire.h> 
#include<LiquidCrystal_I2C.h>

LiquidCrystal_I2C lcd(0x27,2,1,0,4,5,6,7,3,POSITIVE);

void setup()
{
  lcd.begin(20,4);
  lcd.print("Hello World!!!");  
}

void loop()
{
}

Data logger

Schemat data loggera:

Progam testujący zapis na karcie SD i zegar czasu rzeczywistego:

#include<Wire.h> 
#include<LiquidCrystal_I2C.h>

LiquidCrystal_I2C lcd(0x27,2,1,0,4,5,6,7,3,POSITIVE);

#include<SPI.h>
#include<SD.h>
File outputFile;

#include"RTClib.h"

RTC_DS1307 RTC;

void stop()
{
  for(;;){}
}


void setup()
{
  char filename[13]="TEST.TXT";

  lcd.begin(16,2);

  if(!SD.begin(10))
  {
    lcd.print("SD card failed.");
    stop();
  }
  else
    lcd.print("SD card ok.");
  delay(1000);

  outputFile=SD.open(filename,FILE_WRITE);

  lcd.clear();

  if(!outputFile)
  {
    lcd.print("Can not open file!");
    stop();
  }
  else
  {
    lcd.print("Output file:");
    lcd.setCursor(0,1);
    lcd.print(filename);
    delay(1000);
  }

  outputFile.println("TEST");

  outputFile.close();

  lcd.clear();

  Wire.begin();

  RTC.begin();

  if(!RTC.isrunning())
  {
    lcd.print("RTC failed.");
    RTC.adjust(DateTime(__DATE__, __TIME__));
  }

  delay(1000);

  lcd.clear();

  if(!RTC.isrunning())
  {
    lcd.print("RTC failed.");
    RTC.adjust(DateTime(__DATE__, __TIME__));
  }
  else
  {
    lcd.print("RTC set.");
  }

  delay(1000);

  lcd.clear();
}

void loop()
{
  lcd.setCursor(0,0);
  DateTime now = RTC.now();
  lcd.print(now.year(), DEC);
  lcd.print('/');
  lcd.print(now.month(), DEC);
  lcd.print('/');
  lcd.print(now.day(), DEC);
  lcd.print(' ');
  lcd.setCursor(0,1);
  lcd.print(now.hour(), DEC);
  lcd.print(':');
  lcd.print(now.minute(), DEC);
  lcd.print(':');
  lcd.print(now.second(), DEC);
  lcd.print(' ');

  delay(500);

}

Mega2560:
Połączyć: A4 - D20(SDA), A5 - D21(SCL)
W plikach /usr/share/arduino/libraries/SD/src/utility/Sd2Card.h i /usr/share/arduino/libraries/SD/src/utility/Sd2Card.cpp umieścić definicje:

#define SOFTWARE_SPI
#undef USE_SPI_LIB 1

Problemy z RS232
killall avrdude_bin

Linux: uprawnienia użytkownika
W pliku:
/dev/udev/rules.d/50-udev.rules
umieścić zapis:
KERNEL=="ttyACM[0-9]*", OWNER="username", MODE="0666"

Błędy
"Whenever i have string in my sketch which has threee marksigns in a string (eg: "!!!"), my sketch will make the Mega2560 timeout when uploading [...]: stk500v2_ReceiveMessage(): timeout.", deajan, http://forum.arduino.cc/index.php?topic=83079.15

Arduino DUE LCD
"Edit LiquidCrystal.cpp and add these lines after the inttypes.h include:

#undef digitalPinToTimer
#define digitalPinToTimer(_p) NOT_ON_TIMER