合泰HOLTEK单片机写的，对初学者来说里面的分析思路很有帮助。
#include ht48c10-1.inc
;-------------------------------------------------------
data .section ’data’ ;== data section ==
temp db ? ;temporary data register
disp db ? ;key display register
count1 db ? ;delay loop counter
mask db ? ;mask register
matrix db ? ;key matrix register
;-------------------------------------------------------
code .section at 0 ’code’ ;== program section ==
org 00h ;
jmp start ;
org 04h ;external interrupt subroutine
reti ;for guarantee
org 08h ;timer/event 0 interrupt subroutine
reti ;for guarantee
org 0ch ;timer/event 1 interrupt subroutine
reti ;for guarantee
start: ;
clr intc ;initialize registers
clr tmrc ;to guarantee performance
clr tmr ;(interrupts)
set pac ;(ports)
set pbc ;(input mode)
set pcc ;
main:
set pac ;(1);set port A to input mode
clr pbc ;set port B to output mode
clr pa ;zero port A (latch=0)
set pb ;off LEDs
keyloop: ;
MOV a,0feh ;(2);scan first row of keys
MOV matrix,a ;hold scan code
MOV pac,a ;pa.0 output 0 (latch)
MOV a,pa ;read input state
cpl acc ;;distill input state
and a,0f0h ;;
sz acc ;if any input?
jmp get_key ;yes. get input info
MOV a,0fdh ;(2);no. scan second row
MOV matrix,a ;hold scan code
MOV pac,a ;pa.1 output 0 (latch)
MOV a,pa ;read input state
cpl acc ;;distill input state
and a,0f0h ;;
sz acc ;if any input?
jmp get_key ;yes. get input info
MOV a,0fbh ;(2);no. scan third row
MOV matrix,a ;hold scan code
MOV pac,a ;pa.2 output 0 (latch)
MOV a,pa ;read input state
cpl acc ;;distill input state
and a,0f0h ;;
sz acc ;if any input?
jmp get_key ;yes. get input info
MOV a,0f7h ;(2);no. scan fourth row
MOV matrix,a ;hold scan code
MOV pac,a ;output pa.3 0 (latch)
MOV a,pa ;read input state
cpl acc ;;distill input state
and a,0f0h ;;
sz acc ;if any input?
jmp get_key ;yes. get input info
jmp keyloop ;repeat from keyloop
get_key: ;get input key info
call delays ;debounce
MOV a,pa ;test port A
or a,0fh ;
cpl acc ;
sz acc ;any key hold?
jmp go_on ;yes. go on (some key is pressed)
jmp keyloop ;no. return to scan key again
go_on:
call key_in ;(3) ;calculate table index
tabrdl disp ;(10);load display data
MOV a,disp ;;output data to port B
MOV pb,a ;(11);;
jmp keyloop ;repeat keyloop
key_in proc ;get key number
MOV a,pa ;;hold port A state
MOV temp,a ;(4) ;;
get_release: ;wait for the key to be released
MOV a,pa ;;test port A state
cpl acc ;;
and a,0f0h ;;
sz acc ;(6) ;if release?
jmp get_release ;no. keep up waiting
MOV a,0fh ;yes. calculate key number
andm a,matrix ;(7) ;mask low nibble of scan code
MOV a,0 ;keep table index at register A
get_row: ;calculate row number
rrc matrix ;;check each bit to get row number
snz status.0 ;;
jmp get_next ;if bingo goto get_next
clr c ;
add a,4h ;(8) ;table index +4 (4 keys a row)
jmp get_row ;continue calculating
get_next: ;
MOV tblp,a ;hold table index at register TBLP
MOV a,0efh ;
MOV mask,a ;; mask = 0111 1111
MOV a,0fh ;
orm a,temp ;; temp = XXXX 1111
get_column: ;calculate column number
MOV a,temp ;load temp
xor a,mask ;;test column number
snz z ;;
jmp index ;no. test next column
ret ;yes. return (TBLP)
index: ;next column
inc tblp ;(9) ;table index +1
set c ;
rlc mask ;shift mask left (LSB=1)
jmp get_column ;repeat get_column
key_in endp
delays proc ;delay subroutine
MOV a,0ffh ;load counter
MOV count1,a ;
d1:
sdz count1 ;count down count1
jmp d1
ret
delays endp
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