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[on:]

Hello,

I am trying to port print commands for a serial LCD to an I2C LCD.  Here is the code I am using that has the serial LCD print commands.  I need to know how to print the results using an I2C LCD using the LiquidCrystal_I2C library.  I know how to #include the libraries for the I2C, I just do not know how to convert the LCD printing related commands such as "sprintf(databuff,"CV:%3d Cnm:%3d",sensorValueTest,i);" to print to my I2C LCD.  Replacing the sprintf with lcd.print obviously does not work.

Code:

#include <EEPROM.h>
#include <SoftwareSerial.h>

//Set up the Liquid Crystal Display  
#define LCDIn 3
#define LCDOut 2
SoftwareSerial mySerialPort(LCDIn, LCDOut);

//LCD Display buffers
char databuff[16];
char dispbuff[16];

// Variables needed for RGB calculations
float Gamma = 1.00;
int MaxIntensity = 255;
float fBlue;
float fGreen;
float fRed;
float Factor;

int iR;
int iG;
int iB;

//Our eyes can generally see light wavelengths between 350 and 700 nanometers.
//Here, we start the RGB Led with 350
int i = 350;

//RGB is plugged into these arduino digital pins
const int redOutPin = 8;
const int greenOutPin = 6;
const int blueOutPin = 4;

// LED to be tested is plugged into A0
int testPin = A0;    

// variables to store the value coming from the sensor
int sensorValueTest =0;  
int oldTest =0;
int peaknm =0;

//EEPROM start data
int addr=0;

//Music
int notelen = 90;
int dlx = 130;

void setup()
{
  pinMode(LCDOut, OUTPUT);
  pinMode(LCDIn, INPUT);

//Set the RGB LED pins to output

  pinMode(redOutPin, OUTPUT);
  pinMode(greenOutPin, OUTPUT);
  pinMode(blueOutPin, OUTPUT);


// Initialize the LCD display
  mySerialPort.begin(9600);
  mySerialPort.write(0xFE);
  mySerialPort.write(0x01);

  // test to see if the RGB LED works
  makeColor(i);
  analogWrite(redOutPin,255-iR);
  analogWrite(greenOutPin, 255-iG);
  analogWrite(blueOutPin, 255-iB);
  delay(5000);
}

void loop()
{

// set the RGB LED to a specific color
  makeColor(i);
  analogWrite(redOutPin, 255-iR);
  analogWrite(greenOutPin, 255-iG);
  analogWrite(blueOutPin, 255-iB);
  delay(500);
  
// read the sensitivity of the Test LED
  sensorValueTest= analogRead(testPin);

  if (sensorValueTest > oldTest)
  {
    oldTest = sensorValueTest;
    peaknm = i;
  }

// Display the values on the LCD
  sprintf(databuff,"CV:%3d Cnm:%3d",sensorValueTest,i);  
  sprintf(dispbuff,"%-16s",databuff);
  mySerialPort.print(dispbuff);

  sprintf(databuff,"XV:%3d Xnm:%3d",oldTest, peaknm);
  sprintf(dispbuff,"%-16s",databuff);
  mySerialPort.print(dispbuff);



  writeData();
  i++;

  // If we've reached the upper limit of 700 nm, play a little melody  
  if (i>700)
  {
    for (int f = 0; f<=100; f++)
    {
      tone(7,196,notelen);
      delay(dlx);

      tone(7,131,notelen);
      delay(dlx);

      tone(7,261,notelen);
      delay(dlx);

      tone(7,330,notelen);
      delay(dlx);

      tone(7,294,notelen);
    }
    delay(10000);
  }
}



void writeData()
{
  int quotient = i/256;
  int mod = i % 256;

  EEPROM.write(addr++,quotient);
  EEPROM.write(addr++,mod);

  quotient = sensorValueTest/256;
  mod = sensorValueTest % 256;
  EEPROM.write(addr++,quotient);
  EEPROM.write(addr++,mod);
}



void makeColor(int lambda)
{
  if (lambda >= 350 && lambda <= 439)
  {
    fRed    = -(lambda - (float)440.0) / ((float)440.0 - (float)350.0);
    fGreen = (float)0.0;
    fBlue = (float)1.0;
  }
  else if (lambda >= (float)440.0 && lambda <= (float)489.0)
  {
    fRed = 0.0;
    fGreen = (lambda - (float)440.0) / ((float)490.0 - (float)440.0);
    fBlue = 1.0;
  }
  else if (lambda >= (float)490.0 && lambda <= (float)509.0)
  {
    fRed = 0.0;
    fGreen = 1.0;
    fBlue = -(lambda - (float)510.0) / ((float)510.0 - (float)490.0);

  }
  else if (lambda >= (float)510.0 && lambda <= (float)579.0)
  {
    fRed = (lambda - (float)510.0) / ((float)580.0 - (float)510.0);
    fGreen = 1.0;
    fBlue = 0.0;
  }
  else if (lambda >= (float)580.0 && lambda <= (float)644.0)
  {
    fRed = 1.0;
    fGreen = -(lambda - (float)645.0) / ((float)645.0 - (float)580.0);
    fBlue = 0.0;
  }
  else if (lambda >= 645.0 && lambda <= 780.0)
  {
    fRed = 1.0;
    fGreen = 0.0;
    fBlue = 0.0;
  }
  else
  {
    fRed = 0.0;
    fGreen = 0.0;
    fBlue = 0.0;
  }

  if (lambda >= 350 && lambda <= 419)
  {
    Factor = 0.3 + 0.7*(lambda - (float)350.0) / ((float)420.0 - (float)350.0);
  }
  else if (lambda >= 420 && lambda <= 700)
  {
    Factor = 1.0;
  }
  else if (lambda >= 701 && lambda <= 780)
  {
    Factor = 0.3 + 0.7*((float)780.0 - lambda) / ((float)780.0 - (float)700.0);
  }
  else
  {
    Factor = 0.0;
  }
  iR = factorAdjust(fRed, Factor, MaxIntensity, Gamma);
  iG = factorAdjust(fGreen, Factor, MaxIntensity, Gamma);
  iB = factorAdjust(fBlue, Factor, MaxIntensity, Gamma);
}

int factorAdjust(float C, float Factor, int MaxIntensity, float Gamma)
{
  if(C == 0.0)
  {
    return 0;
  }
  else
  {
    return (int) round(MaxIntensity * pow(C * Factor, Gamma));
  }
}

[Reply #1 on:]

The sprintf commands are not actually doing the printing, they are putting data into a buffer ready to be printed.

Can you print text to your LCD with command such as

Code:

  lcd.print("Hello, world!");

If so, then all you need to do in the sketch is to initialise the LCD for use with I2C and replace the

Code:

  mySerialPort.print(dispbuff);

command with

Code:

lcd.print(dispbuff);

Sample code for use with an I2C LCD

Code:

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

LiquidCrystal_I2C lcd(0x20,16,2);  // set the LCD address to 0x20 for a 16 chars and 2 line display

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

void loop()
{
}

[Reply #2 on:]

Yes, lcd.print("Hello, world!"); works just fine.  I will make the changes that you recommend and let you know how it goes.  Thank you.

[Reply #3 on:]

That worked perfectly, thank you!  Always a good day when I get help making something work and learn why in the process.