Hi all 8051 Gurus,
I am new to this group and to 8051 as well. I tried to connect a ps/2
keyboard to my 8051 board with lcd(hd44780, 2x16) and wrote a program
to print the ascii character of the key pressed on lcd. I could detect
the make code and getting the key pressed but the break codes or some
other stuff adds some funny character after the real one. How to avoid
that ? and what should be the logic to detect the key ascii?
pls. help.
the code is :
; KBD1.ASM
;===============================================================
; AA (hex) i.e. 170 dec is power on test successfull
;
; H/W CONNECTIONS : KBD CLOCK connected to P3.2(INT0)
; KBD DATA connected to P3.4
;
; pc-kbd, 89C52,
; assembler : asm51
;===============================================================
$MOD51 ; ASSEMBLER DIRECTIVE FOR ASM51 ASSEMBLER
BYTE_IDX EQU 30H
CR EQU 0
L_SHIFT EQU 0
R_SHIFT EQU 0
CAPS_LOCK EQU 0
NUM_LOCK EQU 0
BACK_SPACE EQU 0
ESC EQU 0
L_CTRL EQU 0
ORG 0000H
JMP START
ORG 0003H
JMP EXT_INT0
START:
CLR BYTE_IDX ;1ST BYTE IS MAKE CODE, THEN COMES TWO BYTES OF BREAK
CODE
MOV P3,#0FFH ;Port 3 set for second function
MOV IE,#81H ;ExtInt0 ENABLED
SETB IT0 ;EDGE TRIGGERED INT 0
MOV DPTR, #COMMANDS
SEND_CMD:
CLR A
MOVC A,@A+DPTR
JZ SEND_DATA
ACALL control_word
ACALL ddelay
INC DPTR
SJMP SEND_CMD
SEND_DATA:
AGAIN:
mov a,#08Fh ; 1st row 16TH COL
acall control_word
acall ddelay
MOV DPTR, #MSG
NXT: CLR A
MOVC A,@A+DPTR
JZ DISP1
ACALL data_word
ACALL ddelay
INC DPTR
SJMP NXT
DISP1: SJMP AGAIN
WAIT: SETB P2.2
JMP WAIT
;--------------------------------------------
control_word:
mov r0,a
anl a,#0F0h
swap a
orl a,#0e0h
mov P2, A
anl a,#0cfh
mov P2, A
mov a,r0
anl a,#0fh
orl a,#0e0h
mov P2, A
anl a,#0cfh
mov P2, A
ret
data_word:
mov r0,a
anl a,#0F0h
swap a
orl a,#0f0h
mov P2, A
anl a,#0dfh
mov P2, A
mov a,r0
anl a,#0fh
orl a,#0f0h
mov P2, A
anl a,#0dfh
mov P2, A
ret
;***************************** isr
EXT_INT0:
; MOV A, BYTE_IDX
; CJNE A, #10,EXIT_ISR
KBD: MOV R3,#8
MOV R7,#0
KP1: MOV C,P3.2
JC KP1
K4: MOV C,P3.2
JNC K4
K5: MOV C,P3.2
JC K5
MOV C,P3.4
MOV A,R7
RRC A
MOV R7,A
K6: MOV C,P3.2
JNC K6
DJNZ R3,K5
ACALL DELAY1
MOV R5,A
;acc contains the key-scan code **/*/*/*/*/*/*
MOV DPTR,#SCAN2ASCII_LOOK_UP
MOVC A,@A+DPTR
ACALL data_word
ACALL ddelay
INC BYTE_IDX
SEC_INT:
EXIT_ISR: RETI
;*************************************
DELAY1: MOV R4,#80H
DJNZ R4,$
RET
;*************************************************
dDELAY: MOV R3,#250 ;50
HERE: MOV R4,#255
DJNZ R4, $
DJNZ R3, HERE
RET
DELAY:
MOV R1,#0FFH
MOV R2,#0FFH
LP: NOP
NOP
DJNZ R1,$
DJNZ R2,LP
RET
L_DELAY:
MOV R1,#0FFH
MOV R2,#0FFH
MOV R3,#04h
LP1: NOP
NOP
DJNZ R1,LP1
DJNZ R2,LP1
DJNZ R3,LP1
RET
;##########################################################################
;BIN2BCD
; CONVERTS 8-BIT BINARY VARIABLE IN ACC TO 3-DIGIT PACKED BCD
FORMAT.
; HUNDRED'S PLACE LEFT IN VARIABLE 'HUND',
; TEN'S AND ONE'S PLACES IN 'TENONE'.
; USES/AFFECTS : ACC, B
HUND DATA 21H
TENS DATA 22H
ONES DATA 23H
BIN2BCD:
MOV B,#100
DIV AB
MOV HUND,A
MOV A,#10
XCH A,B
DIV AB
MOV TENS,A
MOV ONES,B
; SWAP A
; ADD A,B
; MOV TENONE,A
RET
;##########################################################################
COMMANDS:
DB 028H, 028H ;
DB 0EH
DB 01H
DB 06H
DB 07H
DB 0
MSG: DB 'KBD ', 0
SCAN2ASCII_LOOK_UP:
DB 0 ;FOR SCAN-CODE 0 WHICH DOES NOT EXIST, I
SUPPOSE
DB 0,0,0,0,0,0,0,0,0,0 ; scan code 001 to 010
DB 0,0,0,0,0,0,0,0,L_SHIFT,L_CTRL ; scan code 011 to
020
DB 'Q','!',0,0,0,'Z','S','A','W','@' ; scan code 021
to 030
DB 0,0,'C','X','D','E','$','#',0,0 ; scan code 031 to
040
DB SP,'V','F','T','R','%',0,0,'N','B' ; scan code 041
to 050
DB 'H','G','Y','^',0,0,0,'M','J','U' ; scan code 051
to 060
DB '&','*',0,0,'<','K','I','O',')','(' ; scan code 061
to 070
DB 0,0,'>','?','L',':','P','_',0,0 ; scan code 071 to
080
DB 0,'"',0,'{','+',0,0,CAPS_LOCK,R_SHIFT,CR ; scan
code 081 to 090
DB '}',0,'|',0,0,0,0,0,0,0 ; scan code 091 to 100
DB 0,BACK_SPACE,0,0,0,0,0,0,0,0 ; scan code 101 to 110
DB 0,0,0,0,0,0,0,ESC,NUM_LOCK,0 ; scan code 111 to 120
DB 0,0,0,0,0,0,0,0,0,0 ; scan code 121 to 130
DB 0,0,0,0,0,0,0,0,0,0 ; scan code 131 to 140
DB 0,0,0,0,0,0,0,0,0,0 ; scan code 141 to 150
DB 0,0,0,0,0,0,0,0,0,0 ; scan code 151 to 160
DB 0,0,0,0,0,0,0,0,0,0 ; scan code 161 to 170
DB 0,0,0,0,0,0,0,0,0,0 ; scan code 171 to 180
DB 0,0,0,0,0,0,0,0,0,0 ; scan code 181 to 190
DB 0,0,0,0,0,0,0,0,0,0 ; scan code 191 to 200
DB 0,0,0,0,0,0,0,0,0,0 ; scan code 201 to 210
DB 0,0,0,0,0,0,0,0,0,0 ; scan code 211 to 220
DB 0,0,0,0,0,0,0,0,0,0 ; scan code 221 to 230
DB 0,0,0,0,0,0,0,0,0,0 ; scan code 231 to 240
DB 0,0,0,0,0,0,0,0,0,0 ; scan code 241 to 250
DB 0,0,0,0,0,0,0,0,0,0 ; scan code 251 to 260
;=========================================================================
END
thanks in anticipation.
Rajesh Bij
PS/2 Keyboard on 8051
Started by ●June 5, 2006
Reply by ●June 5, 20062006-06-05
rajeshbij@gmail.com wrote:> Hi all 8051 Gurus, > I am new to this group and to 8051 as well.I would recommend you join the message board at 8052.com. There are lot's of 8051 developers there and the question about PS2 keyboards has been covered several times so the info you need should be there. Ian
Reply by ●June 5, 20062006-06-05
rajeshbij@gmail.com wrote:> Hi all 8051 Gurus, > I am new to this group and to 8051 as well. I tried to connect a ps/2 > keyboard to my 8051 board with lcd(hd44780, 2x16) and wrote a program > to print the ascii character of the key pressed on lcd. I could detect > the make code and getting the key pressed but the break codes or some > other stuff adds some funny character after the real one. How to avoid > that ? and what should be the logic to detect the key ascii? > pls. help. > thanks in anticipation. > > Rajesh BijCheck this site: http://www.beyondlogic.org/keyboard/keybrd.htm It has everything you need to know. I did this myself a while ago, but I used a PIC16F628. I had absolutely no problems using this document. It gives you the scan codes for the keys. Also as a note, I didn't look over your code, you should always read the response byte after you pass a byte to the keyboard. If you don't it will likely reject (or just ignore) any subsequent commands you pass to it (Did reject on one of my keyboards although it is not supposed to I believe). -Isaac
