INCLUDE 89c51.mc
ORG 0000H
MAIN:
MOV A,#00H
MOV TMOD,#01H
MOV P2,#00H
LOOP: MOV R6,A
ACALL READ_KEY
JNC SKIP
MOV A,R6
SKIP: ACALL OUTLED
JMP LOOP
;****************************************************************
;KEYBoard matrix 4x4: initial value P1 = 11111110
; 1 1 1 1
; P1.4 P1.5 P1.6 P1.7
; -----------------------------
; 1 P1.3 | f1 f2 f3 f4
; 1 P1.2 | f5 f6 f7 f8
; 1 P1.1 | f9 f10 f11 f12
; 0 P1.0 | f13 f14 f15 f16
GETKEY:
PUSH 02H;R2 BANK1
PUSH 06H;R6 BANK1
PUSH 07H;R7 BANK1
MOV A,#0FEH
MOV R6,#4 ;control 4 row
TEST:
MOV P1,A ;initial value PO 111111110
MOV R7,A
MOV A,P1 ;get value after buttuon pushed from P1
ANL A,#0F0H ;clear 4 low BIT (row PO- > P3)
CJNE A,#0F0H,HINT_KEY ;normally if the button don't push,clear 4 low bit=>A=0F0H
MOV A,R7
RL A
DJNZ R6,TEST
CLR C ; C = 0 alarm none of button is pushed
LJMP EXIT
HINT_KEY:
MOV R7,A
MOV A,#4
CLR C
DEC R6
MOV A,R6
ADD A,R6
ADD A,R6
ADD A,R6
;R6x4
MOV R6,A
MOV A,R7
CLR C
SWAP A;swap to test 4 high bit (detect column)
MOV R2,#4 ; alternative test 4 columns(test 4 high bit)
AGAIN:
RRC A ;swap to find the location of bit whose value =0
JNC DONE ;If C = 0 find out the location of bit ,the value of which is 0
INC R6
;if u don't find bit 0,check another column and increase localtion (R6) 1
;in one column ,the local of 2 button in succession is different 4
DJNZ R2,AGAIN
DONE:
MOV A,R6 ;Value of R6 is the local of button pushed (ex: button f16 is pushed then R6 = 15)
SETB C; C = 1 there is button pushed
; C = 0 none of button is pushed
EXIT: NOP
POP 07H;Tra lai gia tri cua R7 truoc ham Getkey
POP 06H; R6
POP 02H; R2
;cac gia tri tra lai cho R7,R6,R2 nam trong ngan xep da luu giu boi POP
RET
;****************************************************************
READ_KEY:
PUSH 03H ;LUU NOI DUNG CUA R3 TRONG NGAN XEP DE SAU DO DUNG LAI
NHOK: MOV R3,#50
BACK: ; protect button shaking
ACALL GETKEY
JNC NHOK
DJNZ R3,BACK
PUSH ACC
BACK2:
MOV R3,#50
BACK3:
ACALL GETKEY
JC BACK2
DJNZ R3,BACK3
POP ACC
POP 03H
RET
;********************************************
OUTLED:
MOV DPTR,#BANGLED
MOVC A,@A+DPTR
MOV P3,A
RET
BANGLED:
; the oder of buttons 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
; A = 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
DB 09H , 0BDH, 13H, 91H, 0A5H, 0C1H, 41H, 9DH, 01H, 81H , 09H , 0BDH, 13H, 91H, 0A5H, 0C1H
END
#use fast_io(A)
#use fast_io(B)
const char dakeys[4][4]={ { 7 , 8 , 9 ,'/'},
{ 4 , 5 , 6 ,'*'},
{ 1 , 2 , 3 ,'-'},
{'c', 0 ,'=','+'}};
char Read_Keyb()
{ int h=0xE0;
int i,j,k;
for (i=0;i<4;i++)
{
output_b(h);
delay_ms(1);
k=input_a();
if ((k & 0xf) != 0xf)
{
for(j=0;j<4;j++)
{if(bit_test(k,0)==0) return dakeys[j][i];
k=k>>1;}
}
h = (h<<1) | 0x10;
}
return 0xff;
}
