Hello
I am an engineeering student, and have interest in 8051 microcontroller
and am presently trying to write a pc at keyboard interfacing program in 8051
assembly. here i am reading the keyboard and converting it to its
relevant ascii code and sending it to the uart
its almost 10 days and i am not getting results

i have made the circuit in the following way ...
PORT 1 (P1.0) - connected to kbd clock line
PORT 1 (P1.1) - connected to kbd data line

PORT 1 (P3.0/RXD) - connected to Rxd of MAX232
PORT 1 (P3.1/TXD) - connected to Txd of MAX232

and while execution i am supposed to get the relevant ascii code
for the pressed key , sent by the micro, for this i am running HYPER TERMINAL
program, but the micro is not at all sending anythig

i am including all the code to , could anyone tell me what could
be the possible problem.

;################################################# ######################
;
; KBD kbdata - uC PORT P3.1 (PIN 11)
; KBD kbclock - uC PORT P3.2 (PIN 12)
; KBD Xfer Check BIT - uC PORT P3.3 (PIN 13)
; KBD Download LED - uC PORT P3.6 (PIN 16)
;
;*********************** KEYBOARD EQUATES ************************************

shiftf bit 18h ; shift flag 0=no shift key is pressed,1=shift key is pressed

kbdata equ p1.0 ; 8051 pin for KBD data line
kbclock equ p1.1 ; 8051 pin for KBD clock line
dnldled equ p1.5 ; led pin to denote a KBD transfer is in progress
; kbchk equ p3.3 ; KBD check bit, 0 indicates Display, 1 indicates KBDProg

lastkey equ 60h ; last pressed KBD key
curkey equ 61h ; current pressed KBD key


org 0000h
sjmp main ; jump to main program

main:
;******************** POWER SUPPLY SETTLING LOOP *****************************

mov r0,#0ffh ;wait for power resetling time
mov r1,#0ffh ;at the time of powering up
mov r2,#0fh
ploop:
djnz r0,ploop
djnz r1,ploop
djnz r2,ploop

CLR TR1
MOV SCON,#01011010B ;TI set indicates transmitter ready.
; mode 1,REN
MOV TMOD,#00100001B ;Timer 1 is set to 8 bit auto reload mode
orl pcon,#10000000B ; Set to double rate.
mov th1,#0fah ; Set reload value (4800 baud after smod set)
setb tr1 ; start timer.

;************************ KEYBOARD INITIALIZTION *****************************
setb dnldled
clr kbclock ; clr kbclock to make it not to send any data
clr kbdata ; clr kbdata to make not to check any key press
clr shiftf ; clear shift flag to tell shift key is not pressed
mov lastkey,#00h ; initialize the value of the last pressed key
mov curkey,#00h ; initialize the value of the current pressed key

; JNB RI,$ ;Wait until character received.
; MOV A,SBUF ;Read input character.
; CLR RI ;Clear reception flag.
;
; CLR TI ;Clear interrupt flag.
; MOV SBUF,A ;Write out character.
; JNB TI,$ ;Wait until transmission completed.

kbdprog:
clr dnldled ; make p3.6 low to make the download led ON
mov r7,#8 ; take data bit count in r7
mov curkey,#0 ; initialize curkey location to store the data from the kbd
setb kbdata ; make kbd data line high (IDLE)
setb kbclock ; make kbd clock line high (IDLE)
chksbit:
mov c,kbclock ; read clock line bit in carry flag
jc chksbit ; chk if it is high than keep checking clock line till it goes low
mov c,kbdata ; once it is low read the data line for a start bit
jc chksbit ; if the start bit is high it is an invalid start
; bit so repeat theprocess to get the start bit again
chkdbit:
mov c,kbclock ; once a valid start bit is detected chk clock low for next data bit
jc chkdbit ; keep checking till the clock line goes low
mov c,kbdata ; once the clock goes low read the data bit
mov a,curkey ; take the current key value in a
rr a ; rotate it to right with carry so that
mov acc.7,c
mov curkey,a ; the LSB of key data will get into curkey
djnz r7,chkdbit ; chk if 8 data bits have been read, if not then get next data bit
chkpbit:
mov c,kbclock ; read clock line for the last but one bit which
jc chkpbit ; is the parity bit
nop ; no parity checking
chklbit:
mov c,kbclock ; read clock line for the last bit which
jc chklbit ; is the stop bit
; mov c,kbdata ; stop bit data
; jc vlddata ; if stop is a logic high than it is a valid key and data is valid
; sjmp krepeat ; if stop bit is low invalid stop bit so leave the key data
vlddata:
mov a,lastkey ; check if last scan code sent was an E0 than
; cjne a,#0e0h,chkcurk ; simply make the current scan code as the
; mov a,curkey ; get current key in acc
; mov lastkey,a ; store it in lastkey
; sjmp krepeat
;chkcurk:
; mov a,curkey ; check if the current scan code is an E0
; cjne a,#0e0h,chkshift ; than make it as the last scan code
; mov lastkey,a
; sjmp krepeat
;chkshift:
cjne a,#12h,noshift ; check if current scan code is a shift key
mov a,lastkey
cjne a,#0f0h,makesft ; yes than chk if the lastkey was an f0(break key)
clr shiftf ; yes than its a shift key break so clear shift flag
mov lastkey,#12h ; and make shift key as the lastkey
sjmp kbdprog
makesft:
setb shiftf ; if lastkey is not F0 when curkey is shift key set shift flag
mov lastkey,#12h ; store shift key as lastkey
sjmp kbdprog
noshift:
cjne a,#0f0h,nobreak ; if current key is not shift key chk if it is a Break key(F0)
mov lastkey,a ; yes than store it as the last key
sjmp kbdprog
nobreak:
mov a,lastkey ; if non of the above key means may be a valid data key
cjne a,#0f0h,no_f0 ; chk if last key was a break key
mov lastkey,#0 ; yes than make 0 as the lastkey
sjmp kbdprog
no_f0:
setb dnldled
mov a,curkey ; if lastkey is not a break key than
mov lastkey,a ; make the curkey as the lastkey
jnb shiftf,loadunsft ; if shift key is not set load the unshifted data
mov dptr,#shift ; if shift key is set load the shifted data
sjmp getkeyval
loadunsft:
mov dptr,#unshift
getkeyval: ; get the key value
movc a,@a+dptr
cjne a,#0,dataval ; if key value is 1Fh, not a valid data
sjmp kbdprog

;**************************** STORE DATA TO I2C MEMORY ******************************

dataval:
; send this data to the console
CLR TI ;Clear interrupt flag.
MOV SBUF,A ;Write out character.
JNB TI,$ ;Wait until transmission completed.
ajmp kbdprog


;sendpc:
; CLR TI ;Clear interrupt flag.
; MOV SBUF,A ;Write out character.
; JNB TI,$ ;Wait until transmission completed.
; ret


;recvpc:
; JNB RI,$ ;Wait until character received.
; MOV A,SBUF ;Read input character.
; CLR RI ;Clear reception flag.
; ret

;s_init:

; ret



;************************************************* **********************
; UNSHIFTED KEY CODES - Begin
;************************************************* **********************
unshift:
db 0 ;0
db 0 ;1-F9
db 0 ;2
db 0 ;3-F5
db 0 ;4-F3 - denotes animation 3
db 0 ;5-F1 - denotes animation 1
db 0 ;6-F2 - denotes animation 2
db 0 ;7-F12
db 0 ;8-
db 0 ;9-F10
db 0 ;A-F8
db 0 ;B-F6
db 0 ;C-F4
db 09h ;D-TAB
db '`' ;E-`~
db 0 ;F-
db 0 ;10-
db 0 ;11-ALT(Left)
db 0 ;12-SHIFT(Left)
db 0 ;13-
db 0 ;14-CTRL(Left)
db 'q' ;15-Q
db '1' ;16-1!
db 0 ;17-
db 0 ;18-
db 0 ;19-
db 'z' ;1A-Z
db 's' ;1B-S
db 'a' ;1C-A
db 'w' ;1D-W
db '2' ;1E-2@
db 0 ;1F-
db 0 ;20-
db 'c' ;21-C
db 'x' ;22-X
db 'd' ;23-D
db 'e' ;24-E
db '4' ;25-4$
db '3' ;26-3#
db 0 ;27-
db 0 ;28-
db ' ' ;29-SPACE
db 'v' ;2A-V
db 'f' ;2B-F
db 't' ;2C-T
db 'r' ;2D-R
db '5' ;2E-5%
db 0 ;2F-
db 0 ;30-
db 'n' ;31-N
db 'b' ;32-B
db 'h' ;33-H
db 'g' ;34-G
db 'y' ;35-Y
db '6' ;36-6^
db 0 ;37-
db 0 ;38-
db 0 ;39-
db 'm' ;3A-M
db 'j' ;3B-J
db 'u' ;3C-U
db '7' ;3D-7&
db '8' ;3E-8*
db 0 ;3F-
db 0 ;40-
db ',' ;41-,<
db 'k' ;42-K
db 'i' ;43-I
db 'o' ;44-O
db '0' ;45-0)
db '9' ;46-9(
db 0 ;47-
db 0 ;48-
db '.' ;49->.
db '/' ;4A-/?
db 'l' ;4B-L
db ';' ;4C-;:
db 'p' ;4D-P
db '-' ;4E-_-
db 0 ;4F-
db 0 ;50-
db ',' ;51-
db 0 ;52-'"
db 0 ;53-
db '[' ;54-[{
db '=' ;55-+=
db 0 ;56-
db 0 ;57-
db 0 ;58-CAPS
db 0 ;59-SHIFT(Right)
db 13 ;5A-ENTER
db ']' ;5B-]}
db 0 ;5C-
db 92 ;5D-\|
db 0 ;5E-
db 0 ;5F-
db 0 ;60-
db 0 ;61-
db 0 ;62-
db 0 ;63-
db 0 ;64-
db 0 ;65-
db 8 ;66-BACKSPACE
db 0 ;67-
db 0 ;68-
db 0 ;69-1(Numeric)
db 0 ;6A-
db 0 ;6B-4(Numeric)
db 0 ;6C-7(Numeric)
db 0 ;6D-
db 0 ;6E-
db 0 ;6F-
db 0 ;70-0(Numeric)
db 127 ;71-.(Numeric)
db 0 ;72-2(Numeric)
db 0 ;73-5(Numeric)
db 0 ;74-6(Numeric)
db 27 ;75-8(Numeric)
db 0 ;76-ESC
db 0 ;77-NUM KEY
db 0 ;78-F11
db '+' ;79-+(Numeric)
db 0 ;7A-3(Numeric)
db '-' ;7B--(Numeric)
db '*' ;7C-*(Numeric)
db 0 ;7D-9(Numeric)
db 0 ;7E-
db 0 ;7F-
;
;************************************************* **********************
; UNSHIFTED KEY CODES - End
;************************************************* **********************
;************************************************* **********************
; SHIFTED KEY CODES - Begin
;************************************************* **********************
shift:
db 0 ;0
db 0 ;1-F9
db 0 ;2
db 0 ;3-F5
db 0 ;4-F3 - denotes animation 3
db 0 ;5-F1 - denotes animation 1
db 0 ;6-F2 - denotes animation 2
db 0 ;7-F12
db 0 ;8-
db 0 ;9-F10
db 0 ;A-F8
db 0 ;B-F6
db 0 ;C-F4
db 0 ;D-TAB
db '~' ;E-`~
db 0 ;F-
db 0 ;10-
db 0 ;11-ALT(Left)
db 0 ;12-SHIFT(Left)
db 0 ;13-
db 0 ;14-CTRL(Left)
db 'Q' ;15-Q
db '!' ;16-1!
db 0 ;17-
db 0 ;18-
db 0 ;19-
db 'Z' ;1A-Z
db 'S' ;1B-S
db 'A' ;1C-A
db 'W' ;1D-W
db '@' ;1E-2@
db 0 ;1F-
db 0 ;20-
db 'C' ;21-C
db 'X' ;22-X
db 'D' ;23-D
db 'E' ;24-E
db '$' ;25-4$
db '#' ;26-3#
db 0 ;27-
db 0 ;28-
db ' ' ;29-SPACE
db 'V' ;2A-V
db 'F' ;2B-F
db 'T' ;2C-T
db 'R' ;2D-R
db '%' ;2E-5%
db 0 ;2F-
db 0 ;30-
db 'N' ;31-N
db 'B' ;32-B
db 'H' ;33-H
db 'G' ;34-G
db 'Y' ;35-Y
db '^' ;36-6^
db 0 ;37-
db 0 ;38-
db 0 ;39-
db 'M' ;3A-M
db 'J' ;3B-J
db 'U' ;3C-U
db '&' ;3D-7&
db '*' ;3E-8*
db 0 ;3F-
db 0 ;40-
db '<' ;41-,<
db 'K' ;42-K
db 'I' ;43-I
db 'O' ;44-O
db ')' ;45-0)
db '(' ;46-9(
db 0 ;47-
db 0 ;48-
db '>' ;49->.
db '?' ;4A-/?
db 'L' ;4B-L
db ':' ;4C-;:
db 'P' ;4D-P
db '_' ;4E-_-
db 0 ;4F-
db 0 ;50-
db 0 ;51-
db '"' ;52-'"
db 0 ;53-
db '{' ;54-[{
db '+' ;55-+=
db 0 ;56-
db 0 ;57-
db 0 ;58-CAPS
db 0 ;59-SHIFT(Right)
db 13 ;5A-ENTER
db '}' ;5B-]}
db 0 ;5C-
db '|' ;5D-\|
db 0 ;5E-
db 0 ;5F-
db 0 ;60-
db 0 ;61-
db 0 ;62-
db 0 ;63-
db 0 ;64-
db 0 ;65-
db 8 ;66-BACKSPACE
db 0 ;67-
db 0 ;68-
db '1' ;69-1(Numeric)
db 0 ;6A-
db '4' ;6B-4(Numeric)
db '7' ;6C-7(Numeric)
db 0 ;6D-
db 0 ;6E-
db 0 ;6F-
db '0' ;70-0(Numeric)
db '.' ;71-.(Numeric)
db '2' ;72-2(Numeric)
db '5' ;73-5(Numeric)
db '6' ;74-6(Numeric)
db '8' ;75-8(Numeric)
db 27 ;76-ESC
db 0 ;77-NUM KEY
db 0 ;78-F11
db '+' ;79-+(Numeric)
db '3' ;7A-3(Numeric)
db '-' ;7B--(Numeric)
db '*' ;7C-*(Numeric)
db '9' ;7D-9(Numeric)
db 0 ;7E-
db 0 ;7F-
;
;************************************************* **********************
; SHIFTED KEY CODES - End
;************************************************* **********************



END



regards

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