How to Use Graphic LCD Display (GLCD 128x64): Examples, Pinouts, and Specs

The Graphic LCD Display (GLCD 128x64) is a versatile graphical liquid crystal display with a resolution of 128x64 pixels. It is widely used in embedded systems and applications to display images, graphics, and text. Unlike character LCDs, the GLCD allows for more complex visual outputs, making it ideal for projects requiring detailed graphical interfaces.

• Embedded systems with graphical user interfaces (GUIs)
• Industrial control panels
• Medical devices
• DIY electronics projects
• Robotics and automation systems
• Educational tools for learning about graphical displays

Below are the key technical details and pin configuration for the GLCD 128x64:

The GLCD 128x64 typically has a 20-pin interface. Below is the pinout and description:

1. Power Supply: Connect the VSS pin to ground and the VDD pin to a 5V power source.
2. Contrast Adjustment: Use a 10kΩ potentiometer connected to the VO pin to adjust the display contrast.
3. Data and Control Lines: Connect the RS, R/W, and E pins to the microcontroller for control signals. Use the DB0-DB7 pins for data transfer.
4. Chip Select: Use the CS1 and CS2 pins to activate the left and right halves of the display, respectively.
5. Backlight: Connect the A and K pins to power the backlight. Use a current-limiting resistor if necessary.

• Ensure the power supply voltage is stable and within the specified range to avoid damage.
• Use decoupling capacitors (e.g., 0.1µF) near the power pins to reduce noise.
• Avoid leaving unused data pins floating; connect them to ground if not in use.
• For optimal contrast, adjust the potentiometer connected to the VO pin carefully.
• Use a compatible library (e.g., U8glib or GLCD) for easier interfacing with microcontrollers.

Below is an example of how to connect and program the GLCD 128x64 with an Arduino UNO using the U8glib library:

#include <U8glib.h>

// Initialize the GLCD with the KS0108 controller
U8GLIB_KS0108 glcd(U8G_PIN_NONE, 10, 11, 12, 9, 8, 7, 6, 5, 4, 3, 2);

void setup() {
  // Begin communication with the GLCD
  glcd.begin();
}

void loop() {
  // Clear the display
  glcd.firstPage();
  do {
    // Draw a simple message
    glcd.setFont(u8g_font_6x10); // Set font size
    glcd.drawStr(10, 20, "Hello, GLCD!"); // Display text
  } while (glcd.nextPage());
  
  delay(1000); // Wait for 1 second
}

• Install the U8glib library in the Arduino IDE before uploading the code.
• Adjust the pin numbers in the code to match your wiring if necessary.

1. No Display Output:

   • Check the power connections (VSS and VDD).
   • Ensure the contrast is properly adjusted using the potentiometer.
   • Verify the CS1 and CS2 pins are correctly configured.

2. Flickering or Unstable Display:

   • Add decoupling capacitors near the power pins.
   • Ensure the backlight current is within the recommended range.

3. Incorrect or Garbled Graphics:

   • Verify the data and control pin connections.
   • Ensure the correct library and controller type (e.g., KS0108) are used in the code.

4. Backlight Not Working:

   • Check the A and K pin connections.
   • Use a suitable resistor to limit the current to the backlight.

Q: Can I use the GLCD 128x64 with a 3.3V microcontroller?
A: Yes, but you will need a level shifter to convert the 3.3V logic to 5V for proper operation.

Q: What is the maximum cable length for connecting the GLCD?
A: Keep the cable length as short as possible (preferably under 30cm) to avoid signal degradation.

Q: Can I display images on the GLCD?
A: Yes, you can display bitmap images by converting them into a compatible format using tools like LCD Assistant.

Q: Is the GLCD compatible with SPI or I2C?
A: No, the GLCD 128x64 uses a parallel interface. However, you can use an external adapter to convert it to SPI or I2C.