How to Use DUOWEISI 12864-889: Examples, Pinouts, and Specs

The DUOWEISI 12864-889 is a graphic LCD module manufactured by LCD, featuring a resolution of 128x64 pixels. This module is widely used in embedded systems for displaying text, graphics, and custom images. Its compact size and versatile functionality make it ideal for applications such as industrial control panels, DIY electronics projects, and user interface displays in consumer electronics.

• Embedded systems and microcontroller projects
• Industrial control panels and instrumentation
• DIY electronics and hobbyist projects
• Consumer electronics with graphical user interfaces
• Data loggers and monitoring systems

The DUOWEISI 12864-889 module 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 3.3V or 5V power source.
2. Contrast Adjustment: Use a 10kΩ potentiometer connected to the VO pin to adjust the display contrast.
3. Data Communication: Choose between 8-bit or 4-bit parallel communication by connecting the DB0-DB7 pins to your microcontroller. Alternatively, use SPI if supported by your module.
4. Backlight: Connect the A (anode) pin to +5V through a current-limiting resistor (e.g., 220Ω) and the K (cathode) pin to ground.
5. Control Signals: Use the RS, R/W, and E pins to send commands and data to the display. The CS1 and CS2 pins control which half of the display is active.

• Ensure the power supply voltage matches the module's requirements (3.3V or 5V).
• Use decoupling capacitors (e.g., 0.1µF) near the power pins to reduce noise.
• Avoid leaving unused data pins floating; tie them to ground if not in use.
• For SPI communication, consult the module's datasheet for specific wiring instructions.
• Handle the module carefully to avoid damaging the LCD screen or backlight.

Below is an example of how to interface the DUOWEISI 12864-889 with an Arduino UNO using the U8g2 library:

#include <U8g2lib.h>

// Initialize the display in 8-bit parallel mode
// Adjust the pin numbers to match your wiring
U8G2_ST7920_128X64_F_HW_SPI u8g2(U8G2_R0, /* CS=*/ 10, /* R/W=*/ 9, /* RS=*/ 8);

void setup() {
  u8g2.begin(); // Initialize the display
  u8g2.setContrast(100); // Adjust contrast (0-255)
}

void loop() {
  u8g2.clearBuffer(); // Clear the display buffer
  u8g2.setFont(u8g2_font_ncenB08_tr); // Set font
  u8g2.drawStr(0, 10, "Hello, World!"); // Display text
  u8g2.sendBuffer(); // Send buffer to the display
  delay(1000); // Wait for 1 second
}

Note: Install the U8g2 library in the Arduino IDE before using this code. You can do this via the Library Manager.

1. No Display Output:

   • Verify the power supply connections (VSS and VDD).
   • Check the contrast adjustment (VO pin) using a potentiometer.
   • Ensure the backlight (A and K pins) is properly connected.

2. Flickering or Unstable Display:

   • Add decoupling capacitors (e.g., 0.1µF) near the power pins.
   • Check for loose or poor connections in the circuit.

3. Incorrect or Garbled Text/Graphics:

   • Verify the data communication mode (8-bit or 4-bit) and wiring.
   • Ensure the microcontroller's code matches the display's configuration.

4. Backlight Not Working:

   • Check the current-limiting resistor value for the backlight.
   • Ensure the A and K pins are correctly connected to power and ground.

Q: Can I use this module with a 3.3V microcontroller?
A: Yes, the DUOWEISI 12864-889 supports both 3.3V and 5V logic levels. Ensure the power supply matches your microcontroller's voltage.

Q: How do I display custom graphics?
A: Use graphic design software to create a 128x64 monochrome bitmap, then convert it to a byte array using tools like LCD Assistant. Load the array into your microcontroller's code.

Q: Is SPI faster than parallel communication?
A: Yes, SPI is generally faster and requires fewer pins, but it depends on your specific application and microcontroller.

Q: Can I daisy-chain multiple displays?
A: No, the DUOWEISI 12864-889 does not support daisy-chaining. Each display requires separate control signals.