20x4字符液晶的函数

#include

#define lcd_data_port PORTA
#define lcd_data_ddr DDRA
#define lcd_busy_pin PINA
#define lcd_busy_ddr DDRA
#define lcd_control_port PORTC
#define lcd_control_ddr DDRC

#define lcd_RS 0x01 
//PORTC0
#define lcd_RW 0x02 
//PORTC1
#define lcd_EN 0x04 
//PORTC2
#define busy 0x80   
//LCD_DB7

/*----------------------------------函数声明----------------------------------*/
//IO口相关
void io_init(void);

//LCD相关
void lcd_init(void);
void lcd_write_command(unsigned char command,unsigned char wait_en);
void lcd_write_data(unsigned char char_data);
void wait_enable(void);
void display_a_char(unsigned char position,unsigned char char_data);
void display_a_string(unsigned char position,unsigned char *ptr);
void display_a_number(unsigned char position,int i);
int ntentimes(unsigned char n);

//全局变量
unsigned char str0[]="Hello,word!";

void main(void)
{

 unsigned int i=518;
 io_init();
 lcd_init();
 display_a_char(0,'a');
 display_a_string(20,str0);
 display_a_number(40,i);

 }

//液晶初始化
void lcd_init(void)
 {  
    delay_nms(30);
    lcd_data_port=0xff;
    lcd_data_ddr=0xff;
    lcd_control_port=0x00;
    lcd_control_ddr=0x07;
    lcd_write_command(0x38,0);//显示模式设置三次(此时不管lcd空闲与否)
    delay_nms(1);
    lcd_write_command(0x38,0);
    delay_nms(1);
    lcd_write_command(0x38,0);
    delay_nms(1);
    
    lcd_write_command(0x38,1);//显示模式设置(从此之后均需lcd空闲)
    lcd_write_command(0x08,1);//显示关闭
    lcd_write_command(0x01,1);//显示清屏
    lcd_write_command(0x06,1);//显示光标移动设置
    lcd_write_command(0x0c,1);//显示开及光标设置
    delay_nus(30);
    lcd_write_command(0x01,1);//显示清屏
 }

//写指令函数: E=高脉冲 RS=0 RW=0//command为指令，wait_en指定是否要检测LCD忙信号
void lcd_write_command(unsigned char command,unsigned char wait_en)
 {
    if(wait_en)wait_enable();//若wait_en为1，则要检测LCD忙信号，等待其空闲
    lcd_control_port&=~lcd_RS;//RS=0
    lcd_control_port&=~lcd_RW;//RW=0
    lcd_control_port&=~lcd_EN;//E=0,下面给LCD一个高脉冲
    lcd_data_ddr=0xff;
    lcd_data_port=command;
    lcd_control_port|=lcd_EN;//E=1
    lcd_data_port=command;
    lcd_control_port&=~lcd_EN;//重设E=0
 }

//写数据函数: E =高脉冲 RS=1 RW=0
void lcd_write_data(unsigned char char_data)
 {
    wait_enable();//等待LCD空闲
    lcd_control_port|=lcd_RS;//RS=1数据
    lcd_control_port&=~lcd_RW;//RW=0写
    lcd_control_port&=~lcd_EN;//E=0,下面给LCD一个高脉冲
    lcd_data_ddr=0xff;
    lcd_data_port=char_data;
    lcd_control_port|=lcd_EN;//E=1
    lcd_data_port=char_data;
    lcd_control_port&=~lcd_EN;//重设E=0
 }

//正常读写操作之前必须检测LCD控制器状态:E=1 RS=0 RW=1;DB7: 0 空闲，1 忙。
//检测忙信号,等待LCD空闲函数
void wait_enable(void)
 {
    lcd_busy_ddr&=~busy;//设置busy口为输入
    lcd_control_port&=~lcd_RS;//RS=0
    lcd_control_port|=lcd_RW;//RW=1
    lcd_control_port&=~lcd_EN;//E=0,下面给LCD一个高脉冲
    NOP();
    lcd_control_port|=lcd_EN;//E=1
    while(lcd_busy_pin&busy);//等待LCD_DB7为0
    lcd_control_port&=~lcd_EN;//重设E=0
    lcd_busy_ddr|=busy;//设置busy口为输出
 }

void display_a_char(unsigned char position,unsigned char char_data)//参数position指定位置0~79,char_data为要显示的字符
 {
    unsigned char position_tem;
    if(position<20) //第一行时，地址为0x80到0x93，输入的数值加上0x80, 就是当前的地址值；
     position_tem=position+0x80;
    else if(position<40)//第二行的地址为0xc0到0xd3，当为第二行时position>20,此时地址值应为position+0xc0-0x20即position+0xac；
     position_tem=position+0xac; 
    else if(position<60)//第三行的地址为0x94到0xa7，当为第三行时position>40,此时地址值应为position+0x94-0x40即position+0x6c；
     position_tem=position+0x6c;
    else//第四行的地址为0xd4到0xe7，当为第三行时position>60,此时地址值应为position+0xd4-0x60即position+0x98；
     position_tem=position+0x98; 
    lcd_write_command(position_tem,1);
    lcd_write_data(char_data);
 }

//指定位置显示任意大小字符串
void display_a_string(unsigned char position,unsigned char *ptr)
 {
    unsigned char position_tem,i=0,i_tem=0;
    lcd_data_port=0xff;
    lcd_data_ddr=0xff;
    lcd_control_port=0x07;
    lcd_control_ddr=0x07;
    for(i=0;*(ptr+i)!=0;i++)
    i_tem++;
    position_tem=position;
    for(i=0;i     display_a_char(position_tem++,*(ptr+i));
 }
//指定位置显示一个整数
void display_a_number(unsigned char position,int num)
 {
  int j;
  unsigned char i,x;
  if(num>=10000)i=5;
  else if(num<10000&&num>=1000)i=4;
  else if(num<1000&&num>=100)i=3;
  else if(num<100&&num>=10)i=2;
  else if(num<10&&num>=0)i=1;
  else if(num<=-10000)i=15;
  else if(num>-10000&&num<=-1000)i=14;
  else if(num>-1000&&num<=-100)i=13;
  else if(num>-100&&num<=-10)i=12;
  else i=11;
  if(i<10)
   {for(;i>0;i--)
     {
      j=ntentimes(i-1);
      x=num/j;
      display_a_char(position,x+0x30);
      num=num%j;
      position++;
     }
   }
  else
   {
    i-=10;
    display_a_char(position,'-');
    position++;
    for(;i>0;i--)
     {
      j=ntentimes(i);
      x=num/j;
      display_a_char(position,x+0x30);
      num=num%j;
      position++;
     }
   }
 }
//n的10次方转换
int ntentimes(unsigned char n)
 {int m=1;
  for(;n>0;n--)
   {m*=10;}
  return(m);
 }
/*------------------------------------延时函数--------------------------------*/
void delay_ns(unsigned int n)
{
    unsigned int i,j;
    for(i=0;i      {for(j=1000;j>0;j--)
      delay_1ms();
      }
}
//n ms延时函数
void delay_nms(unsigned int n)
{
    unsigned int i;
    n-=n/1000;
    for(;n!=0;n--){for(i=1328;i!=0;i--) ; }
}
//1ms延时函数
void delay_1ms(void)
{
    unsigned int i;
    for(i=1328;i!=0;i--);
}
//n us延时函数
void delay_nus(int n)
 {while(n--);}
/*-----------------------------------端口初始化-------------------------------*/
void io_init(void)
 {DDRA=0xff;
  PORTA=0x00;
  DDRB=0x00;
  PORTB=0xff;
  DDRC=0x07;
  PORTC=0x07;
  DDRD=0xff;
  PORTD=0xf0;
  DDRE=0x07;
  PORTE=0x00;
  }