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原理图
原理图如上。用51拓展一块8255后将lcd连接在8255上。将数据传到8255的PA口让lcd显示，但是数据少了两位，设置值应该是3000转每分钟，下面也少了一位。求大神解惑。
单片机源程序
#include <REGX51.H>
#include <ABSACC.h>
#define SET8255 XBYTE[0x8ff3]
#define PA XBYTE[0x8ff0]
#define PB XBYTE[0x8ff1]
uchar aa[]={'S','e','t','u','p',':',' ',' ',' ',' ',' ','r','/','m','i','n'}; //目标转速。 r/min
uchar cc[]={' ',' ',' ',' ',' ',' ',' ',' ','r','/','m','i','n',' ',' ',' '}; //实测转速: r/min
void write_com(unsigned char com) //写命令
{
SET8255=0x80;//设置8255
PB=0xf8;//rs=0 rw=0
PA=com;
DelayMs(10);//en=1
PB=0xf9;
DelayMs(10);//en=0
PB=0xf8;
}
void write_data(unsigned char date) //写一个字符
{
SET8255=0x80;
PB=0xfc;
PA=date;
DelayMs(10);
PB=0xfd;
DelayMs(10);
PB=0xfc;
}
void init() //初始化
{
write_com(0x38);
write_com(0x0c);
write_com(0x06);
write_com(0x01);
}
/*------------------------------------------------
写入字符串函数
------------------------------------------------*/
void LCD_Write_String(unsigned char x,unsigned char y,unsigned char *s)
{
if (y == 0)
{
write_com(0x80 + x);
}
else
{
write_com(0xC0 + x);
}
while (*s)
{
write_data( *s);
s ++;
}
}
void SetSpeed()
{
if(AddSpeed==0)
{
delay(200);
if(AddSpeed==0)
{
SpeedSet+=10;
if(SpeedSet>3500)
{
SpeedSet=3500;
}
}
}
if(SubSpeed==0)
{
delay(200);
if(SubSpeed==0)
{
SpeedSet-=10;
if(SpeedSet<0) SpeedSet=0;
}
}
aa[7]=SpeedSet/1000+'0';
aa[8]=SpeedSet/100%10+'0';
aa[9]=SpeedSet/10%10+'0';
aa[10]=SpeedSet%10+'0';
LCD_Write_String(0,0,aa);
}
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