How to interface a Black On White Graphic LCD with a microcontroller?

Interfacing a Black On White Graphic LCD with a microcontroller is a fundamental skill in the realm of embedded systems and electronics. As a supplier of Black On White Graphic LCDs, I've witnessed firsthand the transformative impact these displays can have on a wide range of applications, from consumer electronics to industrial control systems. In this blog post, I'll guide you through the process of interfacing a Black On White Graphic LCD with a microcontroller, sharing insights and best practices along the way.

Understanding Black On White Graphic LCDs

Before delving into the interfacing process, it's essential to understand the basics of Black On White Graphic LCDs. These displays use liquid crystal technology to create visual representations of data. Unlike character LCDs, which are designed to display text, graphic LCDs can display complex images, charts, and graphics. The "black on white" designation refers to the color scheme, where the text and graphics appear in black against a white background.

Black On White Graphic LCDs offer several advantages over other types of displays. They are energy-efficient, have a long lifespan, and provide excellent visibility in various lighting conditions. Additionally, they are relatively inexpensive and easy to integrate into electronic systems.

Choosing the Right Microcontroller

The first step in interfacing a Black On White Graphic LCD with a microcontroller is selecting the right microcontroller for your project. The choice of microcontroller depends on several factors, including the complexity of the application, the required processing power, and the available resources.

Some popular microcontrollers for interfacing with LCDs include the Arduino, Raspberry Pi, and PIC microcontrollers. These microcontrollers are widely available, easy to use, and have extensive community support. When choosing a microcontroller, consider the following:

• Processing Power: Ensure that the microcontroller has enough processing power to handle the graphics and data processing requirements of your application.
• I/O Pins: The microcontroller should have sufficient input/output (I/O) pins to connect to the LCD. The number of required pins depends on the interface type of the LCD.
• Communication Protocols: Check if the microcontroller supports the communication protocols used by the LCD, such as Serial Peripheral Interface (SPI), Inter-Integrated Circuit (I2C), or Parallel Interface.

Interfacing Methods

There are several methods for interfacing a Black On White Graphic LCD with a microcontroller, each with its own advantages and disadvantages. The most common interfacing methods are:

Parallel Interface

The parallel interface is the simplest and most straightforward method for interfacing an LCD with a microcontroller. In a parallel interface, the microcontroller sends data to the LCD using multiple data lines simultaneously. This method allows for high-speed data transfer but requires a large number of I/O pins on the microcontroller.

To interface an LCD using a parallel interface, connect the data lines, control lines (such as RS, RW, and E), and power lines of the LCD to the corresponding pins on the microcontroller. The microcontroller then sends commands and data to the LCD by setting the appropriate pins high or low.

Serial Peripheral Interface (SPI)

The SPI interface is a synchronous serial communication protocol that allows for high-speed data transfer between the microcontroller and the LCD. In an SPI interface, the microcontroller sends data to the LCD using a single data line (MOSI) and receives data from the LCD using another data line (MISO). The clock signal (SCK) is used to synchronize the data transfer.

To interface an LCD using an SPI interface, connect the MOSI, MISO, SCK, and chip select (CS) lines of the LCD to the corresponding pins on the microcontroller. The microcontroller then sends commands and data to the LCD by setting the CS line low and sending the appropriate data on the MOSI line.

Inter-Integrated Circuit (I2C)

The I2C interface is a multi-master, multi-slave serial communication protocol that allows for communication between multiple devices using a single data line (SDA) and a single clock line (SCL). In an I2C interface, the microcontroller acts as the master device, and the LCD acts as the slave device.

To interface an LCD using an I2C interface, connect the SDA and SCL lines of the LCD to the corresponding pins on the microcontroller. The microcontroller then sends commands and data to the LCD by sending the appropriate address and data on the SDA line.

Connecting the LCD to the Microcontroller

Once you've chosen the interfacing method, it's time to connect the LCD to the microcontroller. The following steps outline the general process for connecting an LCD to a microcontroller:

1. Power the LCD: Connect the power lines (VSS, VDD, and V0) of the LCD to the appropriate power supply pins on the microcontroller. Make sure to provide the correct voltage and ground connections.
2. Connect the Data Lines: Depending on the interfacing method, connect the data lines of the LCD to the corresponding data pins on the microcontroller. For a parallel interface, connect all the data lines. For an SPI or I2C interface, connect the appropriate data lines (MOSI, MISO, SDA, etc.).
3. Connect the Control Lines: Connect the control lines (such as RS, RW, E, CS, etc.) of the LCD to the corresponding control pins on the microcontroller. These lines are used to control the operation of the LCD, such as selecting the command or data register and enabling the data transfer.
4. Connect the Backlight (Optional): If the LCD has a backlight, connect the backlight pins to the appropriate power supply pins on the microcontroller. You can use a transistor or a MOSFET to control the brightness of the backlight.

Programming the Microcontroller

After connecting the LCD to the microcontroller, you need to program the microcontroller to communicate with the LCD. The programming language and development environment you use depend on the microcontroller you've chosen.

Here's a simple example of how to program an Arduino to display text on a Black On White Graphic LCD using the parallel interface:

#include <LiquidCrystal.h>

// initialize the library with the numbers of the interface pins
LiquidCrystal lcd(12, 11, 5, 4, 3, 2);

void setup() {
  // set up the LCD's number of columns and rows:
  lcd.begin(16, 2);
  // Print a message to the LCD.
  lcd.print("Hello, World!");
}

void loop() {
  // set the cursor to column 0, line 1
  // (note: line 1 is the second row, since counting begins with 0):
  lcd.setCursor(0, 1);
  // print the number of seconds since reset:
  lcd.print(millis() / 1000);
}

In this example, we use the LiquidCrystal library to communicate with the LCD. The begin() function initializes the LCD with the specified number of columns and rows, and the print() function is used to display text on the LCD.

Applications of Black On White Graphic LCDs

Black On White Graphic LCDs are used in a wide range of applications, including:

• Consumer Electronics: LCDs are commonly used in consumer electronics such as calculators, watches, and digital cameras. For example, the LCD Home Electronic Scale uses a Black On White Graphic LCD to display the weight measurement.
• Industrial Control Systems: In industrial control systems, LCDs are used to display process data, control parameters, and status information. The LCD Screen Module for Electronic Instrument is designed for use in industrial applications, providing a reliable and easy-to-read display.
• Medical Devices: LCDs are also used in medical devices such as blood pressure monitors, glucose meters, and patient monitors. The Weight Scale Of Character LCD Display is an example of a medical device that uses an LCD to display weight measurements.

Conclusion

Interfacing a Black On White Graphic LCD with a microcontroller is a rewarding and challenging task that requires a basic understanding of electronics and programming. By following the steps outlined in this blog post, you can successfully interface an LCD with a microcontroller and create your own custom displays for a variety of applications.

If you're interested in purchasing Black On White Graphic LCDs for your projects, we invite you to contact us for more information. Our team of experts is ready to assist you in selecting the right LCD for your needs and providing technical support throughout the integration process.

References

• Arduino Documentation: https://www.arduino.cc/reference/en/
• Raspberry Pi Documentation: https://www.raspberrypi.org/documentation/
• PIC Microcontroller Documentation: https://www.microchip.com/wwwproducts/en/PICmicroMCUs