I2C LCD2004
Contents
Introduction
As we all know, though LCD and some other displays greatly enrich the man-machine interaction, they share a common weakness. When they are connected to a controller, multiple IOs will be occupied of the controller which has no so many outer ports. Also it restricts other functions of the controller. Therefore, LCD2004 with an I2C bus is developed to solve the problem.
I2C bus is a type of serial bus invented by PHLIPS. It is a high performance serial bus which has bus ruling and high or low speed device synchronization function required by multiple host system. I2C bus has only two bidirectional signal lines, Serial Data Line (SDA) and Serial Clock Line (SCL). The blue potentiometer on the I2C LCD2004 is used to adjust backlight to make it easier to display on the I2C LCD2004.
- GND: Ground
- VCC: Voltage supply, 5V.
- SDA: Serial data line. Connect to VCC through a pullup resistor.
- SCL: Serial clock line. Connect to VCC through a pullup resistor.
I2C Address
The default address is basically 0x27, in a few cases it may be 0x3F.
Taking the default address of 0x27 as an example, the device address can be modified by shorting the A0/A1/A2 pads; in the default state, A0/A1/A2 is 1, and if the pad is shorted, A0/A1/A2 is 0.
Backlight/Contrast
Backlight can be enabled by jumper cap, unplug the jumper cap to disable the backlight. The blue potentiometer on the back is used to adjust the contrast (the ratio of brightness between the brightest white and the darkest black).
- Shorting Cap: Backlight can be enabled by this cap，unplug this cap to disable the backlight.
- Potentiometer: It is used to adjust the contrast (the clarity of the displayed text), which is increased in the clockwise direction and decreased in the counterclockwise direction.
For Arduino User
Components
- 1 *SunFounder Mars board
- 1 * I2C LCD2004 module
- 1 * USB cable
- Several jump wires
Connect the circuit
See the following table for connection between the I2C LCD2004 and the SunFounder Uno board:
| I2C LCD2004 | Arduino Board |
|---|---|
| GND | GND |
| VCC | 5V |
| SDA | A4 /pin 20 mega2560 |
| SCL | A5 /pin 21 mega2560 |
Add library
Before you upload the code to the control board,you neeed to add the LiquidCrystal_I2C library.
1) Download the LiquidCrystal_I2C library
2) Open the Arduino IDE,Select Sketch -> Include Library -> Add ZIP Library
3) Find the file LiquidCrystal_I2C which you just download. Click it open and then you'll be prompted by "Library added to your libraries. Check 'Import libraries'”. You also can see the libraries just imported have appeared on the list by Sketch->Include Library->LiquidCrystal_I2C.
Copy the code
Copy the follwing code to the Arduino IDE
/*****************************************
* name: I2C LCD2004
* function: You should now see your I2C LCD2004 display "Hello,world!","IIC/I2C LCD2004"
* "20 cols, 4 rows","www.sunfounder.com"
********************************/
//Email:service@sunfounder.com
//Website:www.sunfounder.com
/********************************/
// include the library code
#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(); //open the backlight
lcd.setCursor ( 0, 0 ); // go to the top left corner
lcd.print(" Hello,world! "); // write this string on the top row
lcd.setCursor ( 0, 1 ); // go to the 2nd row
lcd.print(" IIC/I2C LCD2004 "); // pad string with spaces for centering
lcd.setCursor ( 0, 2 ); // go to the third row
lcd.print(" 20 cols, 4 rows "); // pad with spaces for centering
lcd.setCursor ( 0, 3 ); // go to the fourth row
lcd.print(" www.sunfounder.com ");
}
/*********************************************************/
void loop()
{
}
/************************************************************/
Upload the code
Before upload the code ,you need to select correct Board and Port,please follow the steps:
1) Click Tools ->Board and select Arduino/Genuino Uno.
2) Then select Tools ->Port.
3) Click to the upload icon to upload the code to the control board
If "Done uploading" appears at the bottom of the window, it means the sketch has been successfully uploaded.
Read I2C Address
If everything is correct, but the display just shows 16 black rectangles on Line 1.it may be the address of i2c is not 0x27,therfore you need to run the following code to read the address,then modify the 0x27 to which you read.
LiquidCrystal_I2C lcd(0x27,16,2);
/*****************************************************
* name:I2C_Address
* function:read the address of the I2C lcd1602
* Connection:
* I2C UNO
* GND GND
* VCC 5V
* SDA A4(pin20 in mega2560)
* SCL A5(pin21 in mega2560)
********************************************************/
#include <Wire.h>
void setup()
{
Wire.begin();
Serial.begin(9600);
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("Unknow 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
}
For Raspberry Pi User
Build the circuit
Setup I2C
Enable the I2C port of your Raspberry Pi (If you have
enabled it, skip this; if you do not know whether you have done that or
not, please continue).
Step 1: Run the following command.
sudo raspi-config
Step 2: 3 Interfacing options.
Step 3: P5 I2C.
Step 4: <Yes>, then <Ok> -> <Finish>.
Step 5: Check whether the i2c modules are loaded and active.
lsmod | grep i2c
Step 6: Then the following codes will appear (the number may be different).
i2c_dev 6276 0 i2c_bcm2708 4121 0
Step 7: Install i2c-tools.
sudo apt-get install i2c-tools
Step 8: Check the address of the I2C device.
i2cdetect -y 1 # For Raspberry Pi 2 and higher version
i2cdetect -y 0 # For Raspberry Pi 1
pi@raspberrypi ~ $ i2cdetect -y 1
0 1 2 3 4 5 6 7 8 9 a b c d e f
00: -- -- -- -- -- -- -- -- -- -- -- -- --
10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
20: -- -- -- -- -- -- -- 27 -- -- -- -- -- -- -- --
30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
70: -- -- -- -- -- -- -- --
If there is an I2C device connected, the address of the device will be displayed.
Step 9: Install libi2c-dev or smbus.
For C language users
sudo apt-get install libi2c-dev
For Python users
sudo pip3 install smbus2
Download and run the code
Step 1: Download the code package.
wget http://wiki.sunfounder.cc/images/3/36/I2c_lcd2004_for_raspberry_pi.zip
Step 2: Extract the package
unzip I2c_lcd2004_for_raspberry_pi.zip
(For C Language Users)
Step 3: If you have not installed wiringPi, then you will need to install it first.
sudo apt-get update git clone https://github.com/WiringPi/WiringPi cd WiringPi ./build
Step 4: You can test whether the wiringPi library is installed successfully or not by the following instruction.
gpio -v
Step 5: Get into the folder of code.
cd ~/I2c_lcd2004_for_raspberry_pi/c
Step 6: Compile.
gcc lcd2004.c –o lcd2004 –lwiringPiDev –lwiringPi
Step 7: Run.
sudo ./lcd2004
(For Python Users)
Step 3: Get into the folder of code.
cd ~/I2c_lcd2004_for_raspberry_pi/python
Step 4: Run.
sudo python lcd2004_show.py
Resources
Arduino I2C LCD2004 Code 
LiquidCrystal_I2C library
Raspberry Pi I2C LCD2004 Code
PCF8574T_datasheet 
