拉幕式數(shù)碼顯示技術(shù)

拉幕式數(shù)碼顯示技術(shù)
1． 實(shí)驗(yàn)任務(wù)
用AT89S51單片機(jī)的P0.0/AD0－P0.7/AD7端口接數(shù)碼管的a－h(huán)端，8位數(shù)碼管的S1－S8通過74LS138譯碼器的Y0－Y7來控制選通每個(gè)數(shù)碼管的位選端。AT89S51單片機(jī)的P1.0－P1.2控制74LS138的A，B，C端子。在8位數(shù)碼管上從右向左循環(huán)顯示“12345678”。能夠比較平滑地看到拉幕的效果。
2． 電路原理圖

圖4.21.1
3． 系統(tǒng)板上硬件連線
（1． 把“單片機(jī)系統(tǒng)”區(qū)域中的P0.0/AD0－P0.7/AD7用8芯排線連接到“動態(tài)數(shù)碼顯示”區(qū)域中的a－h(huán)端口上；
（2． 把“三八譯碼模塊”區(qū)域中的Y0－Y7用8芯排線連接到“動態(tài)數(shù)碼顯示”區(qū)域中的S1－S8端口上；
（3． 把“單片機(jī)系統(tǒng)”區(qū)域中的P1.0－P1.2端口用3根導(dǎo)線連接到“三八譯碼模塊”區(qū)域中的A、B、C“端口上；
4． 程序設(shè)計(jì)方法
（1． 動態(tài)數(shù)碼顯示技術(shù)；如何進(jìn)行動態(tài)掃描，由于一次只能讓一個(gè)數(shù)碼管顯示，因此，要顯示8位的數(shù)據(jù)，必須經(jīng)過讓數(shù)碼管一個(gè)一個(gè)輪流顯示才可以，同時(shí)每個(gè)數(shù)碼管顯示的時(shí)間大約在1ms到4ms之間，所以為了保證正確顯示，我必須每隔1ms，就得刷新一個(gè)數(shù)碼管。而這刷新時(shí)間我們采用單片機(jī)的定時(shí)/計(jì)數(shù)器T0來控制，每定時(shí)1ms對數(shù)碼管刷新一次，T0采用方式2。
（2． 在進(jìn)行數(shù)碼顯示的時(shí)候，要對顯示單元開辟8個(gè)顯示緩沖區(qū)，每個(gè)顯示緩沖區(qū)裝有顯示的不同數(shù)據(jù)即可。
5． 程序框圖

主程序框圖?
中斷服務(wù)程序框圖

圖4.21.2
6． 匯編源程序
DISPBUF EQU 30H
DISPCNT EQU 38H
DISPBIT EQU 39H
T1CNTA EQU 3AH
T1CNTB EQU 3BH
CNT EQU 3CH

ORG 00H
LJMP START
ORG 0BH
LJMP INT_T0
START: MOV DISPCNT,#8
MOV A,#10
MOV R1,#DISPBUF
LP: MOV @R1,A
INC R1
DJNZ DISPCNT,LP
MOV DISPBIT,#00H
MOV T1CNTA,#00H
MOV T1CNTB,#00H
MOV CNT,#00H
MOV TMOD,#01H
MOV TH0,#(65536-1000) / 256
MOV TL0,#(65536-1000) MOD 256
SETB TR0
SETB ET0
SETB EA
SJMP $

INT_T0:
MOV TH0,#(65536-1000) / 256
MOV TL0,#(65536-1000) MOD 256
MOV A,DISPBIT
ADD A,#DISPBUF
MOV R0,A
MOV A,@R0
MOV DPTR,#TABLE
MOVC A,@A+DPTR
MOV P0,A
MOV A,P1
ANL A,#0F8H
ADD A,DISPBIT
MOV P1,A
INC DISPBIT
MOV A,DISPBIT
CJNE A,#08H,NEXT
MOV DISPBIT,#00H
NEXT: INC T1CNTA
MOV A,T1CNTA
CJNE A,#50,LL1
MOV T1CNTA,#00H
INC T1CNTB
MOV A,T1CNTB
CJNE A,#8,LL1
MOV T1CNTB,#00H
INC CNT
MOV A,CNT
CJNE A,#9,LLX
MOV CNT,#00H
MOV A,CNT
LLX: CJNE A,#01H,NEX1
MOV 30H,#8
LL1: LJMP DONE
NEX1: CJNE A,#02H,NEX2
MOV 31H,#8
MOV 30H,#8
LJMP DONE
NEX2: CJNE A,#03H,NEX3
MOV 32H,#8
MOV 31H,#8
MOV 30H,#8
LJMP DONE
NEX3: CJNE A,#04H,NEX4
MOV 33H,#8
MOV 32H,#8
MOV 31H,#8
MOV 30H,#8
LJMP DONE
NEX4: CJNE A,#05H,NEX5
MOV 34H,#8
MOV 33H,#8
MOV 32H,#8
MOV 31H,#8
MOV 30H,#8
LJMP DONE
NEX5: CJNE A,#06H,NEX6
MOV 35H,#8
MOV 34H,#8
MOV 33H,#8
MOV 32H,#8
MOV 31H,#8
MOV 30H,#8
LJMP DONE
NEX6: CJNE A,#07H,NEX7
MOV 36H,#8
MOV 35H,#8
MOV 34H,#8
MOV 33H,#8
MOV 32H,#8
MOV 31H,#8
MOV 30H,#8
LJMP DONE
NEX7: CJNE A,#08H,NEX8
MOV 37H,#8
MOV 36H,#8
MOV 35H,#8
MOV 34H,#8
MOV 33H,#8
MOV 32H,#8
MOV 31H,#8
MOV 30H,#8
LJMP DONE
NEX8: CJNE A,#00H,DONE
MOV 37H,#10
MOV 36H,#10
MOV 35H,#10
MOV 34H,#10
MOV 33H,#10
MOV 32H,#10
MOV 31H,#10
MOV 30H,#10
LL: LJMP DONE
DONE: RETI
TABLE: DB 3FH,06H,5BH,4FH,66H,6DH,7DH,07H,7FH,6FH,00H
END
7． C語言源程序
#include
unsigned char code dispcode[]={0x3f,0x06,0x5b,0x4f,
0x66,0x6d,0x7d,0x07,
0x7f,0x6f,0x77,0x7c,
0x39,0x5e,0x79,0x71,0x00};
unsigned char dispbitcode[]={0xf8,0xf9,0xfa,0xfb,
0xfc,0xfd,0xfe,0xff};
unsigned char dispbuf[8]={16,16,16,16,16,16,16,16};
unsigned char dispbitcnt;
unsigned int t02scnt;
unsigned char t5mscnt;
unsigned char u;
unsigned char i;

void main(void)
{
TMOD=0x02;
TH0=0x06;
TL0=0x06;
TR0=1;
ET0=1;
EA=1;
while(1);
}

void t0(void) interrupt 1 using 0
{
t5mscnt++;
if(t5mscnt==4)
{
t5mscnt=0;
P0=dispcode[dispbuf[dispbitcnt]];
P1=dispbitcode[dispbitcnt];
dispbitcnt++;
if(dispbitcnt==8)
{
dispbitcnt=0;
}
}
t02scnt++;
if(t02scnt==1600)
{
t02scnt=0;
u++;
if(u==9)
{
u=0;
}
for(i=0;i<8;i++)
{
dispbuf[i]=16;
}
for(i=0;i{
dispbuf[i]=8;
}
}
}