lcd1602._c

meg16 的所有功能实例

/****************************************Copyright (c)**************************************************
**                               ADEmbed Development Co.,LTD.                                    
**                                 http://www.adembed.com
**--------------File Info-------------------------------------------------------------------------------
** File name:			lcd1602.c
** Last modified Date:  2008-10-13
** Last Version:		1.0
** Descriptions:		lcd1602 test.
** 
**------------------------------------------------------------------------------------------------------
** Created by:			zhoufeng
** Created date:		2008-10-13
** Version:				1.0
** Descriptions:		
**
**------------------------------------------------------------------------------------------------------
** Modified by:         junbolu
** Modified date:       2008-12-13
** Version:
** Descriptions:
**
**------------------------------------------------------------------------------------------------------
**ICC-AVR application builder : 2008-12-13
**Target : M16
**Crystal: 7.3728Mhz
**
**
**描述：这是一个Lcd1602的测试程序。LCD1602型号为JHD162A 使用８位并口数据传输.
**      
**
**涉及知识点：
**          
**          
**          
*******************************************************************************************************/
/*注意：
本例使用M16，内部RC 7.3728MHz测试通过，
编译平台为ICCAVR 6.31
*/
#include <iom16v.h>
#include <macros.h>
#include"lcd1602.h"

//时钟频率:内部RC振荡8MHz
void delay_1us(void) //延时1us
{//ret:4t+call:4t=8t,8MHz时1t为125ns,8t为1000ns=1us
}

void delay_nus(unsigned int n) //延时n us
{//(8+(4+4)*(n-1)+3)t=(8+8n-8+3)t=(8n+3)t=n us+0.375us,所以约等于1us,特别n越大越精确
 while(--n)
 {
  asm("nop"); //nop需1t
  asm("nop");
  asm("nop");
  asm("nop");
 }
}
void delay_1ms(void) //延时1ms
{//函数调用本身有8t=1us
  delay_nus(999); //为999us
}

void delay_nms(unsigned int n) //延时nms
{//(8+4*(n-1)+3)t+delay_nus=(7+4n)t+delay_nus
 for(;n>0;n--)
 {
  asm("nop"); //再补尝,变成了(7+5n)t+delay_nus
  delay_nus(999); /*delay_nus(m)为(8m+3)t所以delay_nus的参数只要999就可以了
                (7+5n)t+((8m+3)*n)t=(7+8n+8mn)t=7t+n us+mn us
                =7t+(m+1)n us,代入m=999约等于1000n us=n ms,误差仅为7t,不到1us
                */
 }
}

void lcd_wait_enable(void) //LCD等待可写
{
 Data_in(); //置为输入
 clr_rs();
 set_rw();
 delay_nus(1);
 set_en();
 delay_nus(2);
 while((Data_PIN&0x80)>>7);
 clr_en();
 Data_out();
}

void lcd_write_cmd(char cmd,char attrib) //写命令,attrib为0不检查忙状态,否则检查忙状态
{
 if(attrib) lcd_wait_enable();
 clr_rs();
 clr_rw();
 delay_nus(1);
 Data_PORT=cmd;
 delay_nus(1);
 set_en();
 delay_nus(2);
 clr_en();
}

void lcd_set_xy(int x,int y) //设置显示的起始地址,x行,y列
{
 int tmp;
 tmp=y&0x0F;
 x&=0x01;
 if(x) //第二行
  tmp|=0x40;
 tmp|=0x80;
 lcd_write_cmd(tmp,0);
}

void lcd_write_byte(char byte) //写字节
{
 lcd_wait_enable();
 set_rs();
 clr_rw();
 delay_nus(1);
 Data_PORT=byte;
 set_en();
 delay_nus(2);
 clr_en();
}

void lcd_disp_char(int x,int y,char ch) //写字串
{
 lcd_set_xy(x,y);
 lcd_write_byte(ch);
}

void lcd_disp_string(int x,int y,char *s) //写字串,支持换行
{	 
	unsigned char i=0;
    while (*s) 
      {
	   if(y+i<16)
	   {
       	lcd_disp_char(x,y+i,*s);
	   	s++;
	   	i++;
	   }
	   else
	   {
	    delay_nus(50); //换行至少延时20us,否则会造成显示不正常
	    lcd_disp_char(x^1,y+i-16,*s);
	   	s++;
	   	i++;
	   }
      }
}

void lcd_init(void) //初始化液晶
{
 Open_Ctrl();
 Data_out();
 lcd_write_cmd(0x38,0); //显示模式设置（不测试忙信号）共三次
 delay_nms(5);
 lcd_write_cmd(0x38,0);
 delay_nms(5);
 lcd_write_cmd(0x38,0);
 delay_nms(5);

 lcd_write_cmd(0x38,1); //8位数据口,2行显示,5*7点阵
 lcd_write_cmd(0x08,1); //显示关
 lcd_write_cmd(0x01,1); //清屏
 lcd_write_cmd(0x06,1); //数据读,写后AC自增1,画面不动
 lcd_write_cmd(0x0C,1); //显示开
}