Текстовый дисплей 20х4 с I2C входом. Собираем монитор системной информации

#include <Wire.h>

void setup() {
 Wire.begin();
 
  Serial.begin(9600);
  while (!Serial);             // Leonardo: wait for serial monitor
  Serial.println("\nI2C Scanner");
}

void loop() {
  {
  byte error, address;
  int nDevices;
 
  Serial.println("Scanning...");
 
  nDevices = 0;
  for(address = 1; address < 127; address++ )
  {
    // The i2c_scanner uses the return value of
    // the Write.endTransmisstion to see if
    // a device did acknowledge to the address.
    Wire.beginTransmission(address);
    error = Wire.endTransmission();
 
    if (error == 0)
    {
      Serial.print("I2C device found at address 0x");
      if (address<16)
        Serial.print("0");
      Serial.print(address,HEX);
      Serial.println("  !");
 
      nDevices++;
    }
    else if (error==4)
    {
      Serial.print("Unknown error at address 0x");
      if (address<16)
        Serial.print("0");
      Serial.println(address,HEX);
    }    
  }
  if (nDevices == 0)
    Serial.println("No I2C devices found\n");
  else
    Serial.println("done\n");
 
  delay(5000);           // wait 5 seconds for next scan
}
}

LiquidCrystal_I2C lcd(0x27, 20, 4);  // set the LCD address to 0x27 for a  20 chars and 4 line display

void setup()
{
  lcd.init();                      // initialize the lcd 
  lcd.init();
  // Print a message to the LCD.
  lcd.backlight();
  lcd.setCursor(0,1);
  lcd.print("Hello, world!");


}


void loop()
{
}

#include <Wire.h> 
#include "LiquidCrystal_PCF8574.h"

LiquidCrystal_I2C lcd(0x27,20,4);  // set the LCD address to 0x27 for a 20 chars and 4 line display

void setup()
{
  lcd.init();                      // initialize the lcd 
  lcd.backlight();
  Serial.begin(115200);  
}

void loop()
{
  int row, col;
  byte rxbyte;
  byte rxByte1;
  // when characters arrive over the serial port...
  if (Serial.available()) {
    // read all the available characters
    while (Serial.available() > 0) {
      rxbyte = Serial.read();
      if (rxbyte == 254) // Matrix Orbital uses 254 prefix for commands
      {
        while(Serial.available() == 0);
        rxByte1 = Serial.read();
        switch (rxByte1)
        {
        case 66: //backlight on (at previously set brightness)
            while(Serial.available() == 0);
            Serial.read();				
            lcd.backlight();
          break;
        case 70: //backlight off
            lcd.noBacklight();				
          break;
        case 71:  //set cursor position
                  while(Serial.available() == 0);
          col = Serial.read();  //get column byte
                  while(Serial.available() == 0);
          row = Serial.read();
          lcd.setCursor(col-1, row-1);
          break;
        case 72:  //cursor home (reset display position)
          lcd.setCursor(0, 0);
          break;
        case 74:  //show underline cursor
          lcd.cursor();
          break;
        case 75:  //underline cursor off
        case 84:  //block cursor off
          lcd.noCursor();
          lcd.blink_off();
          break;
        case 76:  //move cursor left
    //      lcd.command(16);
          break;
        case 77:  //move cursor right
    //      lcd.command(20);
          break;
        case 78:  //define custom char
          uint8_t charMap[8];
          uint8_t temp;
          uint8_t charPos;
                  while(Serial.available() == 0);
          charPos = Serial.read();
          
          for (temp = 0; temp < 8; temp++)
          {
                    while(Serial.available() == 0);
            charMap[temp] = Serial.read();
          }
          lcd.createChar(charPos, charMap);
          break;
        case 83:  //show blinking block cursor
          lcd.blink_on();
          break;
        case 86:  //GPO OFF
          //implement later
          break;
        case 87:  //GPO ON
          /*temp = serial_getch();
           				if (temp == 1)
           				{
           					GPO1 = GPO_ON;
           				}*/
          break;
        case 88:  //clear display, cursor home
          lcd.clear();
          break;
        case 152: //set and remember (doesn't save value, though)
        case 153: //set backlight brightness
          //not implemented
          break;
    
          //these commands ignored (no parameters)
        case 35: //read serial number
        case 36: //read version number
        case 55: //read module type
        case 59: //exit flow-control mode
        case 65: //auto transmit keypresses
        case 96: //auto-repeat mode off (keypad)
        case 67: //auto line-wrap on
        case 68: //auto line-wrap off
        case 81: //auto scroll on
        case 82: //auto scroll off
        case 104: //init horiz bar graph
        case 109: //init med size digits
        case 115: //init narrow vert bar graph
        case 118: //init wide vert bar graph
          break;
        default:
          //all other commands ignored and parameter byte discarded
                  while(Serial.available() == 0);
          Serial.read();  //dump the command code
          break;
        }
        return;
      } //END OF COMMAND HANDLER  
      
      
      lcd.write(rxbyte);
      return;
    }
  }
}