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ThiÕt kÕ m¹ch logic sè PhÇn III: PhÇn mÒm ®iÒu
khiÓn

ch¬ng I: Ph©n tÝch ch¬ng tr×nh
Ch¬ng tr×nh ®iÒu khiÓn ®îc viÕt b»ng ng«n ng÷ C, ch¹y trong m«i trêng
DOS. Yªu cÇu cña ch¬ng tr×nh lµ ph¶i cã mét giao diÖn th©n thiÖn, gióp ngêi dïng dÔ dµng
dïng m¸y tÝnh ®Ó nhËp çc ký tù cÇn hiÓn thÞ t¹i vÞ trÝ mong muèn trªn ma trËn LED bªn
ngoµi.
Khi thùc hiÖn, ch¬ng tr×nh ph¶i thêng xuyªn trao ®æi d÷ liÖu víi m¹ch ngoµi
qua cæng song song b»ng çch truy nhËp vµo ba thanh ghi cña cæng song song lµ: thanh ghi
d÷ liÖu, thanh ghi tr¹ng th¸i, thanh ghi ®iÒu khiÓn. Ch¬ng tr×nh mÆc ®Þnh l y cæng song
song ë ®©y lµ LPT1 víi ®Þa chØ çc thanh ghi ®îc cho (tÝnh ë hÖ ®Õm 16) nh sau:
Thanh ghi §Þa chØ
D÷ liÖu 378h
Tr¹ng th¸i 379h
§iÒu khiÓn 37Ah

§Ó thuËn tiÖn, trong ch¬ng tr×nh ta dïng lÖnh #define ®Ó ®Þnh nghÜa
cho çc thanh ghi: #define DataReg 0x378
#define StatusReg 0x379
#define ControlReg 0x37A
Thanh ghi d÷ liÖu cã 8 bit (D0 ÷ D7) dïng ®Ó ®a ra ®Þa chØ vµ m· cña ký tù cÇn ghi vµo
RAM ë m¹ch ngoµi. Sö dông lÖnh: outportb(DataReg, d÷ liÖu). §Þa chØ cña ký tù cÇn ghi
vµo RAM sÏ x¸c ®Þnh vÞ trÝ cña ký tù trªn b¶ng qu¶ng ço bªn ngoµi, nã gåm cã ®Þa chØ
cét (4 bit ®Çu, tõ D0 ®Õn D3) vµ ®Þa chØ cét (3 bit tiÕp theo, tõ D4 ®Õn D6), tøc lµ cÇn
7 bit ®Þa chØ D0 ÷ D6, bit thø 8 lµ D7 kh«ng dïng. Gäi column lµ ®Þa chØ cét vµ row lµ
®Þa chØ hµng cña ký tù cÇn hiÓn thÞ th× ®Þa chØ cña ký tù ®ã trong RAM lµ add ®îc
tÝnh nh sau:
row << 4; // dÞch ph¶i 4 bit
add = row | column; // céng ®¹i sè row vµ column
M· cña ký tù dïng 6 bit (D0 ÷ D5) ®Ó biÓu diÔn, tøc lµ cã thÓ biÓu diÔn ® îc 64 ký tù cã m·
tõ 0 ®Õn 63, ®îc qui íc nh b¶ng díi ®©y:
Ký M· Ký M· Ký M·
tù HÖ 10 HÖ 2 tù HÖ 10 HÖ 2 tù HÖ HÖ 2
10
A 0 00000 X 23 010111 ; 46 101110
0
B 1 000001 Y 24 011000 ' 47 101111
C 2 000010 Z 25 011001 " 48 110000
D 3 000011 0 26 011010 ( 49 110001
E 4 000100 1 27 011011 ) 50 110010
F 5 000101 2 28 011100 [ 51 110011
G 6 000110 3 29 011101 ] 52 110100
H 7 000111 4 30 011110 ! 53 110101
I 8 001000 5 31 011111 ? 54 110110
J 9 001001 6 32 100000 @ 55 110111
K 10 001010 7 33 100001 # 56 111000
L 11 001011 8 34 100010 $ 57 111001
M 12 001100 9 35 100011 % 58 111010
N 13 001101 + 36 100100 ^ 59 111011
O 14 001110 - 37 100101 & 60 111100
P 15 001111 * 38 100110 61 111101
Q 16 010000 / 39 100111 | 62 111110
R 17 010001 = 40 101000 space 63 111111
S 18 010010 > 41 101001
T 19 010011 < 42 101010
U 20 010100 . 43 101011
V 21 010101 , 44 101100
W 22 010110 : 45 101101

Thanh ghi tr¹ng th¸i cã 8 bit (S0 ÷ S7), dïng ®Ó thu nhËn nh÷ng th«ng tin tõ
m¹ch bªn ngoµi göi ®Õn qua çc ch©n: 10 vµ 13. Chøc n¨ng tõng ch©n ®îc nªu nh b¶ng díi ®©y:
Bit t¬ng øng

36

ThiÕt kÕ m¹chlogic sè PhÇn III: PhÇn mÒm®iÒu
khiÓn

Ch ©n trªn thanh ghi Ch øc n ¨ng
tr¹ng th ¸i
M¹ch ngoµi göi møc logic 1 ®Ó th«ng b¸o lµ ®ang
10 S6 ®äc RAM. Khi nã cã møc logic 0 th× cã nghÜa lµ
RAM ®· ®îc ®äc xong vµ m¸y tÝnh cã thÓ ghi d÷
liÖu lªn RAM.
13 S4 ë møc logic 1 khi m¹ch ngoµi ®· ®ãng c«ng t¾c
nguån (cã thÓ cha c p nguån cho m¹ch ngoµi).
Khi b¾t ®Çu thùc hiÖn, ch¬ng tr×nh ph¶i kiÓm tra xem c«ng t¾c nguån ë m¹ch ngoµi ®· ®îc
®ãng cha th«ng qua viÖc ®äc d÷ liÖu tõ thanh ghi tr¹ng th¸i vµ kiÓm tra bit S4 cã ë tr¹ng
th¸i 1 kh«ng b»ng çc lÖnh:
result = inportb(StatusReg);
k = result & 16; // PhÐp AND gi÷a result vµ 16
Sè 16 biÓu diÔn díi d¹ng nhÞ ph©n lµ: 00010000. Khi6k ≠ 0 th× S4 = 1.
Tríc khi ghi d÷ liÖu lªn RAM ph¶i kiÓm tra xem bit S cã ë tr¹ng th¸i 0 kh«ng. Qu¸ tr×nh kiÓm
tra ®îc thùc hiÖn ë chÕ ®é hái vßng b»ng çch dïng lÖnh for(i=0;i<1000;i++), tøc lµ liªn
tôc ®äc thanh ghi tr¹ng th¸i, b¾t ®Çu tõ lóc ký tù ®îc nhËp vµo tõ bµn phÝm. Sau mét thêi
gian, nÕu ch©n 10 vÉn ë møc logic 1 th× sÏ tù tho¸t ra vµ qu¸ tr×nh göi ký tù lµ kh«ng thµnh
c«ng.
Thanh ghi ®iÒu khiÓn cã 8 bit (C0 ÷ C7) dïng ®Ó göi th«ng tin ®iÒu khiÓn tõ
m¸y tÝnh ra m¹ch bªn ngoµi b»ng çc ch©n: 1, 14, 17. Chøc n¨ng çc ch©n ®îc cho nh b¶ng díi
®©y:

Bit t¬ng øng
Ch©n trªn thanh ghi Chøc n¨ng
®iÒu khiÓn
Ch¬ng tr×nh sÏ göi mét møc logic 1 ra ch©n nµy
1 C0 ®Ó chèt ®Þa chØ cña ký tù göi ra trªn m¹ch
chèt 74373, ®ång thêi më bé ®Öm 74244 ®a
®Þa chØ tíi RAM.
Sau khi ®Þa chØ vµ d÷ liÖu ®· ®a tíi RAM, ch-
14 C1 ¬ng tr×nh sÏ lµm cho ch©n nµy chuyÓn xuèng møc
logic 0 ®Ó t¹o ra tÝn hiÖu ghi vµo RAM.
Khi ngêi dïng nh n phÝm F1 ®Ó bËt ch¬ng tr×nh,
17 C3 nÕu c«ng t¾c nguån m¹ch ngoµi ®· ® îc ®ãng, ch-
¬ng tr×nh sÏ göi mét møc logic 0 ra ch©n nµy ®Ó
t¹o ra tÝn hiÖu c p nguån cho m¹ch.

37

khiÓn

ch¬ng ii: m· nguån

//Chuong trinh dieu khien bang quang cao dung ma tran LED 5x7
// (Do an mon hoc: Thiet ke mach Logic)
//Nguoi viet: Le Minh Hung
// Nguyen Duc Linh
// Lop DT6-K43-DHBKHN

#include <conio.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
#include <dos.h>

#define DataReg 0x378
#define StatusReg 0x379
#define ControlReg 0x37A

void Initialize();
void Interfacing();
void Print_Code(int code);
void ItoSofB(int i,char up[],char down[]);
void Print_Character(int column,int row,int code);
void Print_Column(int column);
void Print_Row(int row);
void Print_Cell(int column,int row,char value);
void Print_Matrix(int code);
int Out_Char(int column,int row,int code);
void Reset();
void Power();
//-------------------------------------------------------------
----
int character[64][6]={
//character[x][0-4]: code of character'column
//character[x][5]: ASCII code

38

khiÓn

{126,17,17,17,126,65}, // 0-A
{127,73,73,73,54,66}, // 1-B
{62,65,65,65,34,67}, // 2-C
{127,65,65,34,28,68}, // 3-D
{127,73,73,73,65,69}, // 4-E
{127,9,9,9,1,70}, // 5-F
{62,65,73,73,58,71}, // 6-G
{127,8,8,8,127,72}, // 7-H
{0,65,127,65,0,73}, // 8-I
{32,64,65,63,1,74}, // 9-J
{127,8,20,34,65,75}, //10-K
{127,64,64,64,64,76}, //11-L
{127,2,12,2,127,77}, //12-M
{127,4,8,16,127,78}, //13-N
{62,65,65,65,62,79}, //14-O
{127,9,9,9,6,80}, //15-P
{62,65,81,33,94,81}, //16-Q
{127,9,25,41,70,82}, //17-R
{38,73,73,73,50,83}, //18-S
{1,1,127,1,1,84}, //19-T
{63,64,64,64,63,85}, //20-U
{31,32,64,32,31,86}, //21-V
{63,64,48,64,63,87}, //22-W
{99,20,8,20,99,88}, //23-X
{7,8,120,8,7,89}, //24-Y
{97,81,73,69,67,90}, //25-Z
{62,81,73,69,62,48}, //26-0
{0,66,127,64,0,49}, //27-1
{66,97,81,73,70,50}, //28-2
{33,65,69,75,49,51}, //29-3
{24,20,18,127,16,52}, //30-4
{39,69,69,69,57,53}, //31-5
{60,74,73,73,48,54}, //32-6
{1,113,9,5,3,55}, //33-7
{54,73,73,73,54,56}, //34-8
{6,73,73,41,30,57}, //35-9
{8,8,62,8,8,43}, //36-+
{8,8,8,8,8,45}, //37--
{20,8,62,8,20,42}, //38-*
{32,16,8,4,2,47}, //39-/
{20,20,20,20,20,61}, //40-=
{0,65,34,20,8,62}, //41->
{8,20,34,65,0,60}, //42-<
{0,96,96,0,0,46}, //43-.
{0,80,48,0,0,44}, //44-,
{0,54,54,0,0,58}, //45-:
{0,86,54,0,0,59}, //46-;

39

khiÓn

{0,5,3,0,0,39}, //47-'
{0,3,0,3,0,34}, //48-"
{0,28,34,65,0,40}, //49-(
{0,65,34,28,0,41}, //50-)
{0,127,65,65,0,91}, //51-[
{0,65,65,127,0,93}, //52-]
{0,0,95,0,0,33}, //53-!
{2,1,81,9,6,63}, //54-?
{50,73,121,65,62,64}, //55-@
{20,62,20,62,20,35}, //56-#
{36,42,127,42,18,36}, //57-$
{35,19,8,100,98,37}, //58-%
{4,2,1,2,4,94}, //59-^
{54,73,85,34,80,38}, //60-&
{2,4,8,16,32,92}, //61-
{0,0,127,0,0,124}, //62-|
{0,0,0,0,0,32}, //63-
};
int matrix[128];
int power;
//-------------------------------------------------------------
----
void main()
{
int column=0,row=0,pos=0,i;
char scan,ch;

Interfacing();
Initialize();
for(i=0;i<128;i++)
matrix[i]=63;
for(;;)
{
Print_Column(column);
Print_Row(row);
Print_Matrix(matrix[pos]);
Print_Code(matrix[pos]);
window(5+column*2,2+row*2,5+column*2,2+row*2);
if((scan=getch())==0)
{
ch=getch();
switch(ch)
{
case 59: //F1
Power();
break;
case 60: //F2

40

khiÓn

if(power==1)
Reset();
break;
case 75: //Left Arrow
if(power==1)
{
if(pos>0) pos--;
if(column==0)
{
if(row>0)
{
column=16;
row--;
}
else column=1;
}
column--;
}
break;
case 77: //Right Arrow
if(power==1)
{
if(pos<127) pos++;
column++;
if(column>15)
{
if(row<7)
{
column=0;
row++;
}
else column=15;
}
}
break;
case 72: //Up Arrow
if(power==1)
{
if(row>0)
{
pos=pos-16;
row--;
}
}
break;
case 80: //Down Arrow
if(power==1)

41

khiÓn

{
if(row<7)
{
pos=pos+16;
row++;
}
}
break;

} // for switch(ch)
} // for if((scan=getch())==0)
else
{
ch=scan;
switch(ch)
{
case 27: //ESC
//Dua ra tin hieu tat mach ngoai (chan 17,bit3=1)
outportb(ControlReg,8); // 8 = 00001000b
return;
case 13: //Enter
if((row<7)&&(power==1))
{
pos=pos+(16-column);
row++;
column=0;
}
break;
default:
if((isprint(ch))&&(power==1))
{
ch=toupper(ch);
for(i=0;i<64;i++)
if(character[i][5]==ch)
{
Print_Character(column,row,ch);
if(Out_Char(column,row,i)==0)
{
textbackground(LIGHTGRAY);
textcolor(RED);
window(4,25,30,25);clrscr();
cprintf("Khong gui duoc ky tu !");
}
else
{

42

khiÓn

}
matrix[pos]=i;
break;
}
if(pos<127) pos++;
if(column==15)
{
if(row<7)
{
column=-1;
row++;
}
else column=14;
}
column++;
} // for if(isprint(ch))
break;
} // for switch(ch)
} // for else
}
}
//-------------------------------------------------------------
----
void Initialize()
{
//Dong mach ngoai: chan 17,bit3=1
power=0; //Chua cho phep chuong trinh hoat dong
textbackground(BLACK);
textcolor(WHITE);
printf("OFF");
}
//-------------------------------------------------------------
----
void Power()
{
unsigned char result;
if(power==0)
{
//Kiem tra xem chan 13 co o muc cao (bit4=1)
result=inportb(StatusReg);
if(result&16 !=0) // 16=10000b
{
//Neu bit4=1 (mach ngoai da duoc cap nguon)
power=1; //Cho phep chuong trinh hoat dong
textbackground(RED);

43

khiÓn

textcolor(WHITE);
printf("ON");
//Dua ra tin hieu dong mach ngoai (chan 17,bit3=0)
//va thiet lap trang thai ban dau: dong bo dem
74244(chan
//1,bit0=0),khong cho phep ghi vao RAM(chan 14,bit1=1)
}
else
{
textcolor(RED);
cprintf("Chua dong nguon cho mach!");
}
}
else
{
//Khong cho phep chuong trinh hoat dong
power=0;
textcolor(WHITE);
printf("OFF");
//Dua ra tin hieu tat mach ngoai (chan 17,bit3=1)
}
}
//-------------------------------------------------------------
----
void Interfacing()
{
textmode(C40);
textbackground(BLUE);window(0,0,40,25);clrscr();
textbackground(BLACK);window(5,2,37,25);clrscr();
textcolor(BLUE);
textbackground(LIGHTGRAY);window(4,1,36,17);clrscr();
textcolor(LIGHTGRAY);
cprintf(" ³ ³ ³ ³ ³ ³ ³ ³ ³ ³ ³ ³ ³ ³ ³ ");
cprintf("ÄÅÄÅÄÅÄÅÄÅÄÅÄÅÄÅÄÅÄÅÄÅÄÅÄÅÄÅÄÅÄ");
cprintf(" ³ ³ ³ ³ ³ ³ ³ ³ ³ ³ ³ ³ ³ ³ ³ ");
cprintf(" ³ ³ ³ ³ ³ ³ ³ ³ ³ ³ ³ ³ ³ ³ ³ ");
cprintf(" ³ ³ ³ ³ ³ ³ ³ ³ ³ ³ ³ ³ ³ ³ ³ ");

44

khiÓn

cprintf(" ³ ³ ³ ³ ³ ³ ³ ³ ³ ³ ³ ³ ³ ³ ³ ");
cprintf(" ³ ³ ³ ³ ³ ³ ³ ³ ³ ³ ³ ³ ³ ³ ³ ");
cprintf(" ³ ³ ³ ³ ³ ³ ³ ³ ³ ³ ³ ³ ³ ³ ³ ");
cprintf(" ³ ³ ³ ³ ³ ³ ³ ³ ³ ³ ³ ³ ³ ³ ³ r");
textbackground(LIGHTGRAY);window(5,17,35,17);clrscr();
textcolor(BLUE);textbackground(LIGHTGRAY);
window(20,19,30,19);clrscr();cprintf("Column:");
window(20,21,30,21);clrscr();cprintf("Row:");
window(20,23,30,23);clrscr();cprintf("Code:");
window(6,20,17,21);clrscr();cprintf("F1 - Power");
window(6,21,17,22);clrscr();cprintf("F2 - Reset");
window(5,22,17,23);clrscr();cprintf("ESC - Exit");
}
//-------------------------------------------------------------
----
void ItoSofB(int i,char up[],char down[])//Chuyen so nguyen
// sang chuoi cac so nhi
phan
{
int j=0,k=0;
do
{
if(i%2==0) up[j]='0';
else up[j]='1';
j++;
i=i/2;
} while(i!=0);
up[j]='0';
do
{
down[k]=up[j-1];
k++;j--;
} while(j>=0);
down[k-1]='0';
}
//-------------------------------------------------------------
----
void Print_Code(int code)
{

45

khiÓn

char up[7];
char down[7];
textcolor(RED);textbackground(LIGHTGRAY);
itoa(code,up,10);cprintf("%s",up);
ItoSofB(code,up,down);cprintf("%sB",down);
}
//-------------------------------------------------------------
----
void Print_Column(int column)
{
char up[7],down[7];
itoa(column,up,10);cprintf("%s",up);
ItoSofB(column,up,down);cprintf("%sB",down);
}
//-------------------------------------------------------------
----
void Print_Row(int row)
{
char up[7],down[7];
itoa(row,up,10);cprintf("%s",up);
ItoSofB(row,up,down);cprintf("%sB",down);
}
//-------------------------------------------------------------
----
void Print_Cell(int column,int row,char value)
{
if(value=='0')
else
textbackground(RED);
textcolor(WHITE);
window(31+column,18+row,31+column,18+row);clrscr();
printf("%c",value);
}
//-------------------------------------------------------------
----
void Print_Matrix(int code)
{
int i,j,k,len;

46

khiÓn

char up[9];
char down[9];
for(i=0;i<5;i++)
{
k=0;
ItoSofB(character[code][i],up,down);
len=strlen(up);
while(k<8-len)
{
up[len+k]='0';
k++;
}
for(j=0;j<7;j++)
Print_Cell(i,j,up[j]);
}
}
//-------------------------------------------------------------
----
void Print_Character(int column,int row,int code)
{
textcolor(RED);textbackground(BLACK);
window(5+column*2,2+row*2,5+column*2,2+row*2);clrscr();
printf("%c",code);
}
//-------------------------------------------------------------
----
int Out_Char(int column,int row,int code) //Dua ky tu co ma
// code ra cong song
song
{
int i;
unsigned char result;
int add;
row=row<<4;
add=row|column; //Dia chi o nho cua RAM
for(i=0;i<1000;i++) //Hoi vong
{
result=inportb(StatusReg); //Doc trang thai vao
if(result&64==0) //Kiem tra xem chan 10 co o muc thap
//(bit7=0)
{ //64 = 01000000b
//Dua dia chi ra cong song song
outportb(DataReg,add);//Ghi du lieu vao thanh ghi du
lieu
//Dua ra tin hieu chot dia chi 74373
//va mo bo dem 74244 (chan 1,bit0=1)
outportb(ControlReg,3);//Ghi du lieu vao thanh ghi dieu

47

khiÓn

// khien
// 3 = 00000011b
//Dua ma ky tu ra cong song song
outportb(DataReg,code);
//Dua ra tin hieu ghi vao RAM (chan 14,bit1=0);
//Dua ra tin hieu dong bo dem 74244 (bit0=0)
// va khong cho ghi vao RAM (bit1=1)
return 1; // Ket thuc ghi vao RAM
}
}
return 0;
}
//-------------------------------------------------------------
----
void Reset()
{
int i;
//Dua ra tin hieu dong mach (chan 17, bit3=1)
delay(500); // Tre 0.5s
//Thiet lap lai trang thai ban dau: bit0=0(dong bo dem
74244),
//bit1=1(khong cho ghi vao RAM), bit3=0(mo mach)
for(i=0;i<128;i++) //Xoa mang chua cac ky tu ve ky tu trong
matrix[i]=63;
Interfacing(); //Ve lai giao dien
}
//--------------------------------------------------------------------------

ch¬ng III: Híng dÉn sö dông ch¬ng tr×nh
Ch ¬ng tr×nh ®iÒu khiÓn chØ chøa trong mét file tªn lµ: Quangcao.exe, ch¹y
trong m«i tr êng MSDOS.Khi kÝch ho¹t file ®ã th× giao diÖn cña ch¬ng tr×nh sÏ xuÊt hiÖn nh
h×nh III.1.

48

H×nh III.1– Giao diÖn cña ch¬ng t r×nh ®iÒu
khiÓn

khiÓn

PhÇn chÝnh cña giao diÖn lµ mét ma trËn çc « gåm 8 hµng x 16 cét m«
pháng ma trËn ®Ìn qu¶ng ço cña m¹ch thùc. Mçi « lµ n¬i ®Ó hiÓn thÞ ký tù mµ ngêi dïng
nhËp vµo. ë gãc díi bªn ph¶i giao diÖn lµ çc th«ng sè cña « ch÷ t¹i vÞ trÝ con trá mµn h×nh
xuÊt hiÖn gåmcã:
+ Column(cét): chØ sè thø tù cña cét (tõ 0 ®Õn 15) mµ con trá mµn h×nh xuÊt
hiÖn.
+ Row (hµng): chØ sè thø tù cña hµng (tõ 0 ®Õn 7) mµ con trá mµn h×nh
xuÊt hiÖn.
+ Code(m·): chØ m· cña ký tù (theo b¶ng m· qui íc cña chóng t«i ®· ®îc ®a
ra ë ch¬ng I cña phÇn nµy) xuÊthiÖn t¹i vÞ trÝ con trá mµnh×nh.
Bªn c¹nh ®ã lµ ma trËn 5x7 çc « vu«ng biÓu thÞ çc bit 1(®Ìn LEDs¸ng) vµ bit 0 (®Ìn LED
t¾t) cña ma trËn 5x7 LEDøng víi ký tù hiÓn thÞ.
ë gãc díi bªn tr¸i giao diÖn lµ b¶ng chØ dÉn çc phÝmchøc n¨ng:
+ F1– Power: BËt / t¾t ch¬ng tr×nh. Lóc nµy, ch¬ng tr×nh cha ®îc bËt nªn
bªn c¹nh ®ã lµ ch÷ OFF(t¾t). Khi nhÊnF1, ch¬ng tr×nh sÏ kiÓm tra qua cæng song song xem
m¹chngoµi ®· ®îc cÊpnguån hay cha. NÕu m¹chngoµi ®· ®îc cÊpnguån th× ch¬ng tr×nh sÏ göi
tÝn hiÖu ra cæng song song cho phÐp m¹ch ngoµi ho¹t ®éng, ®ång thêi cho phÐp ch¬ng
tr×nh ho¹t ®éng. Lóc ®ã, ch÷ OFF sÏ chuyÓn thµnh ON. NÕu m¹ch ngoµi cha ®îc cÊpnguån
th× ch¬ng tr×nh sÏ hiÖn ra th«ng b¸o lµ: "Cha ®ãng nguån cho m¹ch ngoµi !". Khi ch¬ng
tr×nh ®ang ®îc bËt mµ nhÊnF1 th× ch¬ng tr×nh sÏ göi tÝn hiÖu ra cæng song song kh«ng
cho phÐp m¹chngoµi ho¹t ®éng, ®ång thêi t¾t ch¬ng tr×nh.
+ F2 – Reset: ThiÕt lËp l¹i. Khi ch¬ng tr×nh ®ang ®îc bËt mµ nhÊnF2 th× ch-
¬ng tr×nh sÏ göi tÝn hiÖu ra cæng song song c¾t nguån cÊpcho m¹chngoµi kho¶ng 0.5 s, sau
®ã ®ãng l¹i nh»mthiÕt lËp l¹i hÖ thèng trë vÒ tr¹ng th¸i ban ®Çu. §ång thêi sÏ xo¸ toµn bé
ma trËn çc « ký tù thµnh ký tù tr¾ng (m· 63).
+ ESC– exit: Tho¸t. Khi nhÊnphÝmESCsÏ tho¸t khái ch¬ng tr×nh ®iÒu khiÓn.
Tríc khi tho¸t, ch¬ng tr×nh sÏ göi tÝn hiÖu ra cæng song song ®Ó c¾t c¾t nguån cÊpcho
m¹chngoµi.
Khi ch¬ng tr×nh ®· ®îc bËt, ta cã thÓ dïng çc phÝmmòi tªn (←, ↑, →, ↓)
®Ó di chuyÓn con trá ®Õn vÞ trÝ bÊt kú trªn trang mµn h×nh ®Ó nhËp ký tù cÇn hiÓn
thÞ. Khi ký tù ®îc nhËp vµo, nã hiÓn thÞ t¹i vÞ trÝ con trá mµn h×nh võa ®øng, sau ®ã,
con trá tù ®éng nh¶y sang vÞ trÝ bªn c¹nh. Ch¬ng tr×nh sÏ göi th«ng tin vÒ ký tù võa
nhËp ra cæng song song ®Ó m¹chngoµi hiÓn thÞ, nÕu kh«ng thµnh c«ng th× sÏ cã th«ng b¸o:
"Kh«ng göi ®îc ký tù !".
H×nh III.2 lµ h×nh ¶nh cña ch¬ng tr×nh khi ®· ®îc bËt vµ nhËp çc ký tù. Lóc
nµy, con trá mµnh×nh ®· ®îc dÞch chuyÓn ®Õn cét 2, hµng 2, ký tù t¹i « nµy lµ "L", cã m·
lµ 11.Th«ng tin cña ký tù ®ã cã thÓ thÊy ë gãc díi bªn ph¶i b»ng c¶ sè thËp ph©n vµ sè nhÞ
ph©n.

49

khiÓn

H×nh III.2 – H×nh ¶nh cña ch¬ng t r×nh khi ®îc bËt

50

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Phan iii

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