LCD1602 and keyboard scan job

1. Design task

Under the control of AT89C51, use LCD1602 and two buttons to complete the switching display of two screens: the first screen is the pinyin of your name, the second is your student number; the second screen displays: the first line is your hometown, The second line is his birthday. The display uses LCd commands 1-8 for setting, requiring at least 4 commands.

Two, design ideas

Choose port P0 as the data port; first store the name, student number, hometown and other data in the program memory of the single-chip microcomputer. Then it is connected to LCD1206 through a single-chip computer in the form of a data bus through R/W, E control signals, D0~D7 data or command signals, plus independent keyboard scanning to control whether to display the first screen or the second screen;

Three, hardware circuit

1. LCD1206 display module

Use P0 as the data and command port, P2^0~P2^2 as the control signal port
Insert picture description here

The command word characteristics of LCD1206:

Numbering	command	Rs	$\overline{W}$	D7	D6	D5	D4	D3	D2	D1	D0
1	Clear screen	0	0	0	0	0	0	0	0	0	1
2	Cursor back	0	0	0	0	0	0	0	0	1	$\times$
3	Display mode	0	0	0	0	0	0	0	1	I/D	S
4	Display switch, cursor setting	0	0	0	0	0	0	1	D	C	B
5	Cursor and character shift	0	0	0	0	0	1	S/C	R/L	$\times$	$\times$
6	Function setting	0	0	0	0	1	DL	N	F	$\times$	$\times$
7	CGRAM address	0	0	0	1	word	symbol	Library	Ground	site
8	DDRAm address	0	0	1	number	according to	R	A	M	First	site
9	Read busy flag or address	0	1	BF
10	Write data	1	0
11	Read data	1	1

Command 1: The cursor returns to 00H (upper left corner position)
Command 2: Cursor return
Command 3: Display settings

I/D: (1) Address pointer plus one; (0) Address pointer minus one

S: (1) Write characters, move the whole screen to the left or right; (0) Display the whole screen without moving
Command 4: D——screen display: 1 display on; 0 off display
C——cursor presence or absence: 1 yes; 0 no cursor
B——cursor blinking: 1 blinking; 0 no blinking
Command 5: SC =0 move the cursor SC =1 move the displayed character
RL = 0 move left RL =1 move right
Command 6: DL :1 Eight-bit data 0 Four-bit data interface
N: 1 Two-line display 0 Single-line display
F: (1)5 $× 1 0 \times10$ array (0) 5 $\times7$ dots
Command 7: GGRAM address setting, set user-defined characters
Command 8: Set display address: 80H + display position
Command 9: Read busy: BF =1 busy;
Command 10: Write data
Command 10: Read data
control operation:

operating	The control signal sent by the MCU to the LCD	LCD output
Read status	RS=0, R/ $\overline W$ =1,E= 1	D0~D7 status
Write command	RS=0,R/ $\overline W$ =0, D0~D7 command, E positive pulse	no
Read data	RS =1,R/ $\overline W$ =1,E =1	D0~D7 data
Write data	RS =1,R/ $\overline W$ =0, D0~D7 data, E positive pulse	no

2. Independent keyboard scanning module

Insert picture description here

Four, software design

#include<reg51.h>
#include<intrins.h>
#define out P0  //数据和命令端口
#define uchar unsigned char//预定义
#define uint unsigned int
sbit S1 =P1^0;  // 按键1
sbit S2 =P1^1;//按键2
uchar keyvalue; // 键值
uchar code name[] ="Tang jie";//预存显示数据
uchar code stu_num[] ="180844072";
uchar code birthplace[] ="Tong Ling";
uchar code birthday[] = "2000/01/27";
sbit RS  = P2^0;   //  数据或指令控制线
sbit RW  = P2^1;   // 读写控制线
sbit E   = P2^2;   //使能控制线 
void key_scan(void); //键盘扫描声明
/*********************
延时函数
*********************/
void delay(uint j)
  {
    
    
  uchar i = 250;
  for(;j>0;j--)
  {
    
    
   while (--i);
   i= 249;
   while(--i);
   i=250;
  }
}
/*********************
检查忙函数，检查LCD是否处于忙状态
如果处于忙则持续检查
*********************/
void check_busy(void)
{
    
    
    uchar temp;
    do{
    
    
        temp =0xff;  //
        E = 0;
        RS= 0;   //
        RW = 1;
        E =1;
        temp = out; // 
			}while(temp&0x80);  // 如果 BF =0 则持续检查 
        E = 0; 
}
/*********************
写命令函数
*********************/
void write_command(uchar com)
{
    
    
    check_busy();//  首先检查忙
   E= 0;//预置0
   RS =0;
   RW =0; //按LCD写命令控制信号设置
   out = com;
   E =1; //  正脉冲
   _nop_();// 
   E = 0; // 还原E
    delay(1);
}

void write_data(uchar com) //写数据函数
{
    
    
  check_busy();
  E=0;    //预置0
  RS= 1;
  RW =0;//按LCD写数据控制信号设置
  out = com;
  E=1;// 正脉冲
  _nop_();
  E =0;
delay(1);
  } 
  
void lcd_initial(void) //LCD初始化函数
 {
    
    
  write_command(0x38); // 八位数据，双列显示，5X7阵
	_nop_();
  write_command(0x0c); //开显示屏，关光标，光标不显示
	_nop_();
  write_command(0x06); //字符不移动，每次字符地址加1
	_nop_();
  write_command(0x01); //清屏
	_nop_();
	delay(100);
  }

void string(uchar add, uchar *s)//字符串显函数
{
    
     
	 write_command(add);//显示地址
	 while(*s != '\0')
	{
    
    
	  write_data(*s++);
	}
}

void key_1(void) // 第一屏显示函数
{
    
    
lcd_initial();
string(0x80,stu_num); //第一行第一个开始显示学号
string(0xc0,name);//第二行第一个开始显示姓名
 do{
    
    
	key_scan();
	} while(S2!=0);// 持续进行键盘扫描，如果按键2没按下，则一直显示第一屏
}
void key_2(void) 
{
    
    
lcd_initial();
string(0x80,birthplace);//第一行第一个开始显示籍贯
 string(0xc0,birthday);//第二行第一个开始显示生日
do{
    
    
key_scan();
  } while(S1!=0); //持续进行键盘扫描，如果按键1没按下，则一直显示第一屏
}
	
void key_scan(void)  //独立键盘扫描函数
{
    
    
 P1 =0xff;
 if((P1&0x0f)!=0x0f)
	{
    
    
	  delay(10);
	  if(S1==0)
	   {
    
      
	    keyvalue =1;
		delay(100);
		}
		if(S2 == 0)
	    {
    
    
        keyvalue =2;
		delay(100);
		}
	}
}

void main(void) //主函数
{
    
    
	keyvalue =0;
	while(1)
	{
    
    
	 key_scan();  //按键扫描
	 switch(keyvalue)  //按键值选择显示第几屏数据
	 {
    
    
	 case 1 : key_1();delay(10);break;
	 case 2 : key_2();delay(10);break;
 	 
	 }
	}
}

Five, simulation debugging

Press button 1, the first screen data is displayed, the display is good
Press button 2, the second screen data is displayed, the display is good
Insert picture description here

Simple operation of LCD1602 and independent keyboard