MCU LCD Operation

LCD operation:

1602 LCD can only display ASCI. Today, I will drive 1602 LCD. LCD operation is simpler than digital tube.

 Basic operation sequence of LCD:
1.1 Read state: Input: RS = L, RW = H, E = H Output D0~D7

1.2 Write instruction: Input: RS = L, RW = L, D0~D7 instruction code, E = high pulse, output: none;

RS is the data command selection terminal (H/L);

1.3 Read data: input RS= H, RW=H, E=H

1.4 Write instruction: output, RS = L, RW = L, D0~D7 = data, E = high pulse

Note: Before each read and write operation on the controller, a read and write test must be performed to ensure that STA7 is 0. A simple delay can be used instead.

Initial Setup

Display Mode Settings

Instruction code: 00111000 Function 16*2 display, 5*7 dot matrix, 8 is the instruction of data interface 0x38

Display on/off cursor setting

So left and right are set by N and S

Data pointer instruction code

80H+address code (0-27H, 40H to 67H)

other settings

The function of instruction code 01H is to clear the screen: 1 data pointer cleared, 2 all displays cleared

　　　　02H displays carriage return: 1 data pointer cleared

The circuit diagram is shown in the figure:

 Sample code: Dynamic display

#include

#include

#define uchar unsigned char

#define uint unsigned int

sbit lcden = P2^6; //These ports need to be connected to the hardware circuit first  

sbit lcdrw = P2^5;

sbit lcdrs = P2^4;

sbit dula = P3^1;

sbit wela = P3^2;

uchar num;

uchar code table[]="I LIke MCU!";

uchar code table1[]="I LIke HULeiHao";

void delay(uint z)

{

    uint x,y;

    for(x= z;x>0;x--)

        for(y =110;y>0;y--);

}

void write_com(uchar com) // write command function

{

    lcdrs = 0; // Enable the terminal to 0. Low pulse writes the instruction, high pulse writes the data   

    _nop_(); // postpone one machine cycle  

    lcdrw = 0; //Low level to write data

    P0=com;

    delay(5);

    lcden = 1; // Enable the terminal to give a high level to read data

    delay(5);

    lcden = 0; // Enable the terminal to return to a low level  

}

void write_date(uchar date) // write data function

{

    lcdrs = 1; // Enable the terminal to 0. Low pulse writes the instruction, high pulse writes the data

    _nop_(); // postpone one machine cycle

    lcdrw = 0;

    P0= date;

    delay(5);

    lcden = 1;

    delay(5);

    lcden = 0;

}

void init()

{

    dula = 0;

    wela = 0; // turn off the digital tube

    lcden = 0;

    write_com(0x38); //Display mode setting

    write_com(0x0e); //Display switch and cursor setting

    write_com(0x06);

    write_com(0x80+0x10);

}

void main()

{

    init();

    for(num=0;num<11; num++)

    {

        write_date(table[num]);

        delay(20);

    }

// write_com = 1; // clear screen operation

    write_com(0x80+0x53); //Set data pointer

    for(num=0;num<15; num++)

    {

        write_date(table1[num]);

        delay(20);

    }

    for(num = 0 ;num<16;num++)

    {

        write_com(0x18); //The entire screen moves left

        delay(20);

    }        

    while(1);

}