July 17, 2020

Our header file lcd.h makes interfacing 16×2 character LCD with using Keil C simpler and user friendly. Just include the header file and enjoy. LCD Interfacing with 89C51 – microcontroller – Circuit & C program. Learn how to interface 16 x 2 LCD and microcontroller using C code and circuit. This is a circuit diagram of Interfacing 16X2 LCD with AT89C51 which is a microcontroller family. We use LCD displays for displaying the error messages, etc.

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The module were are talking about here is type number JHDA which is a very popular one. VEE pin is meant for adjusting the contrast of the LCD display and the contrast can be adjusted by varying the voltage at this pin.

See the circuit diagram for better understanding. The JHDA has two built in registers namely data register and command register. Data register is for placing the data to be displayedand the command register is to place the commands. We will discuss in detail about the commands later. If we make RS pin low and put a data on the data line, the module will recognize it as a command. High level at this pin enables read mode and low level at this pin enables write mode. DB0 to DB7 are the data pins.

Each command will make the module to do a particular task. The steps that has to be done for initializing the LCD display is given below and these steps are common for almost all applications.


The steps for sending data to the LCD module is given below. Capacitor C3, resistor R3 and push button switch S1 forms the reset circuitry.

Ceramic capacitors C1,C2 and crystal X1 is related to the clock circuitry which produces the system clock frequency. Resistor R1 limits the current through the back light LED and so do the back light intensity. POT R2 is used for adjusting the contrast of the display. Program for interfacing LCD to microcontroller is shown below.

An LCD module can be interfaced with a microcontroller either in 8 bit mode as seen above or in 4 bit mode. However 4 bit mode uses only 4 data lines along with the control pins. This will saves the number of GPIO pins needed for other purpose.


As shown in the circuit diagram, port 0 of the controller is used for interfacing it with LCD module. This will save us 4 pins of our controller which we might employ it for other purpose. Here we only need to write to the LCD module.

In this way the total number of pins can be reduced to 6. The reset circuit, oscillator circuit and power supply need to be provided for the proper working of the circuit.

LCD interfacing with Microcontroller (AT89C51) – Circuit & C Program

The programming part is done in assembly language instead of embedded C. As mentioned earlier the 8 bit data is break into two 4 bit data and send to LCD.

The necessary commands for the LCD initialization are defined at the end part of the program.


Please check — http: Lcx the 7th bit of the accumulator is 1,then it jumps to DELY. Else it executes the next instruction. Hi I constructed the circuit exactly as it is on my simulator and just copied the program and nothing is appearing on the LCD.

I think that you have use array in c programming. Your email address will not be published. E pin is for enabling the microcontroler. A high to low transition at this pin will enable the module. Send 06H for incrementing cursor position. Send 01H for clearing the display and return the cursor. Sending data to the LCD. Place data byte on the data register. Pulse E from high to low. Repeat above steps for sending another data. Previous post Next post. You may also like: El retardo es demasiado corto.

There is nothing appearing on lcd. Thankyou for taking the efforts! Could you explain me how DELY subroutine produces the delay?

how to interface 16×2 LCD with microcontroller (AT89C51) – CONSBEDDED

Sorry for the question. Anybody can send me the programing for lcd interfacing with microcontroller and xbee s2. Comment if you come across any doubts. Pls provide alp programs for LCD interfacing. Leave a Reply Cancel reply Your email address will not be published.

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