Published June 25, 2017 © GPL3+

What's My I2C Address?

The story of how to make a clock through using a LCD 1602 or LCD 2004 over I2C.

BeginnerShowcase (no instructions)1 hour11,895

Things used in this project

Hardware components

Particle Photon

LCD Display 1602 - 5V

LCD Display 2004 - 5V

optional

I2C Adapter

Jumper wires (generic)

4 pices

Resistor 4.75k ohm

in case you will better sleep to save your LCD - my project works without resistors on top

Breadboard (generic)

Story

The Project

You will find out how to get to the I2C address of your display. If the standard 0x27 does not work, you can optionally connect a 20x4 LCD. Your time formats according to your choice.

After I was informed about the advantages of the I2C (= IIC) port and managed more than 120 objects, I have reordered an I2C adapter. It will upgrade my displays with I2C, and save the wiring of the 16 PINs. The adapter advantageously carries a potentiometer on board, which can adjust brightness. The photo shows a screwdriver that fixes the adapter header after insertion into the LCD. This ensures good contact (the soldering will be done later).

If you want to know more about I2C in conjunction with BME280 and OLE displays, you can follow this other project.

So what do I do if the Particle WebIDE (provided by Jim Brower - thanks! >Link to his GitHub<) and I2C Libary LiquidCrystal_I2C_Spark do not work right away?

First Part

I have tried to run the example of the libary, and I only got bricks on the display.

not that what i want

backside - I2C Adapter

After all, I had GND, VCC and D0 (SDA) and D1 (SCL) as a source of errors. I can exclude some, even if I have not built the resistors from the Particle Doc. The research brought me to change the hex address and so it worked out right away.

   // The address is typically 0x27. I2C Address: 0x3F 
   // https://www.sainsmart.com/new-sainsmart-iic-i2c-twi-1602-serial-lcd-module-display-for-arduino-uno-mega-r3.html 
   lcd = new LiquidCrystal_I2C(0x3F /*address*/, 16 /*columns*/, 2/*rows*/);

This manual approach was trial and error, and could have gone wrong. I am today on this thread from 2014, which an I2C scanner pushed the correct addresses over the serial port. So I feel responsible to document this project over the succession of 3 years.

The I2C scanner has also confirmed the manual search, and thus both the LCD 16x2 and the LCD 20x0 are controlled via the hex address 0x3F.

Second Part

The second part now wants to replace the example code for the clock from the library, and present ways to format its own output.

 lcd->setCursor(0 /*columns*/,0 /*rows*/); 
// lcd->print(Time.timeStr()); 
 lcd->print(Time.format(Time.now(), "%d.%m. %A")); 
// Serial.println(Time.format(Time.now(), "%H:%M:%S")); 
 lcd->setCursor(4,1); 
 lcd->print(Time.format(Time.now(), "%H:%M:%S"));

In addition to determining the position of the output, specifying the column and the row, the formatting of the time.function can also be influenced. There are the small letters that influence the formatting. I have oriented myself to a PHP formatting. The Photon already has the time function on its own; an extension is not necessary on its part.

from brixes on a LCD 20x4 (2004) to

a clock

I haven't change the code:

lcd = new LiquidCrystal_I2C(0x3F /*address*/, 16 /*columns*/, 2/*rows*/);

Better in case you want to use an LCD 2004:

lcd = new LiquidCrystal_I2C(0x3F /*address*/, 20 /*columns*/, 4/*rows*/);

Conclusions

Like my description? You will find more under my account.

Follow me to be notified when I publish new projects!

Here is my Paypal link. You can also send me sensors, which I like to look at sometimes.

Code

#include <LiquidCrystal_I2C_Spark.h>

LiquidCrystal_I2C *lcd;

void setup()
{
    Serial.begin(9600);
    
    // The address is typically 0x27. I2C Address: 0x3F
    // https://www.sainsmart.com/new-sainsmart-iic-i2c-twi-1602-serial-lcd-module-display-for-arduino-uno-mega-r3.html
    lcd = new LiquidCrystal_I2C(0x3F /*address*/, 16 /*columns*/, 2/*rows*/);
    lcd->init();
    lcd->backlight();
    lcd->clear();
    Time.zone(+2.00); // setup a time zone, which is part of the ISO6801 format 
}
    

 
void loop()
{
 // sonst friert die Änderung des Wochentages im Display ein und überlappt sich mit dem Neuen
 if (Time.now(), "%H:%M:%S" == "00:00:00") 
 {
    lcd->clear();
 }  
  
  lcd->setCursor(0 /*columns*/,0 /*rows*/);
 // lcd->print(Time.timeStr());
  lcd->print(Time.format(Time.now(), "%d.%m. %A"));
  
  
 // Serial.println(Time.format(Time.now(), "%H:%M:%S"));
  lcd->setCursor(4,1);
  lcd->print(Time.format(Time.now(), "%H:%M:%S"));

}

    // --------------------------------------
    // i2c_scanner
    //
    // Version 1
    //    This program (or code that looks like it)
    //    can be found in many places.
    //    For example on the Arduino.cc forum.
    //    The original author is not know.
    // Version 2, Juni 2012, Using Arduino 1.0.1
    //     Adapted to be as simple as possible by Arduino.cc user Krodal
    // Version 3, Feb 26  2013
    //    V3 by louarnold
    // Version 4, March 3, 2013, Using Arduino 1.0.3
    //    by Arduino.cc user Krodal.
    //    Changes by louarnold removed.
    //    Scanning addresses changed from 0...127 to 1...119,
    //    according to the i2c scanner by Nick Gammon
    //    http://www.gammon.com.au/forum/?id=10896
    // Version 5, March 28, 2013
    //    As version 4, but address scans now to 127.
    //    A sensor seems to use address 120.
    // Version 6, November 27, 2015.
    //    Added waiting for the Leonardo serial communication.
    //
    //
    // This sketch tests the standard 7-bit addresses
    // Devices with higher bit address might not be seen properly.
    //
    // Source: http://playground.arduino.cc/Main/I2cScanner
    // 2 Changes for Particle user
     
    //#include <Wire.h> = Change 1/2
    #include "application.h"
     
     
    void setup()
    {
      Wire.begin();
     
      Serial.begin(9600);
      //while (!Serial);                    // Leonardo: wait for serial monitor = Change 2/2
      while (!Serial) Particle.process();    // <-- to keep Particle cloud connection alive
      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
    }

Credits

Ingo Lohs

182 projects • 194 followers

I am well over 50 years and come from the middle of Germany.

Thanks to clyde, Hitchhikers, spydrop, peekay123, ScruffR.

What's My I2C Address?

Things used in this project

Hardware components

Story

The Project

First Part

Second Part

Conclusions

Schematics

I2C Scanner

Code

The clock

I2C Scanner

Credits

Ingo Lohs

Comments

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What's My I2C Address?

What's My I2C Address?

Things used in this project

Hardware components

Story

The Project

First Part

Second Part

Conclusions

Schematics

I2C Scanner

Code

The clock

I2C Scanner

Credits

Ingo Lohs

Comments

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