Saturday, January 16, 2016

Interfacing LCD display with serial port (COM port)

Interface LCD display with PC serial port (for HD44780 compliant controllers)

After interfacing the LCD display with parallel port, now let's see how to interface the LCD with serial port (USB to serial port supported). Interfacing LCD display with PC parallel port 

Many types of LCDs are supported such as 20x1, 16x2, 20x4.
With the help of shift register this interfacing uses only two lines DTR and RTS of the serial port as shown in the circuit schematics below. The circuit is very simple and easy to build, the two circuits below can do the job, the first circuit is based on transistors and the second uses MAX232 integrated circuit.
The software used for this interfacing named "Serial Port LCD Display" it is very small and simple.
Note that Microsoft .NET Framework 4 or higher must be installed. It works with all Microsoft Windows versions.
Circuit schematics:
You can choose one from the following two circuit schematics.

lcd display hd44780 with serial port com port rs232

 lcd display hd44780 with serial port com port rs232

The interfacing software has the following main window:
serial port lcd display 

 After connecting to a serial port, the LCD must be initialized before writing texts or sending commands to the LCD.
The interfacing software can be downloaded from the following link:

serial port lcd display video:
The following video is an example shows how to write to the LCD.