 Разработка, производство и продажа радиоэлектронной аппаратуры  |
Требуется программист в Зеленограде
- обработка данных с датчиков; ColdFire; 40 тыс. e-mail:jobsmp@pochta.ru |
; Routine to read a standard 3x4 matrix keypad using
; only 4 wires. Result is output the number on port A.
; History
; 30/11/1998 Mike Rigby-Jones (mikerj@clara.net)
; 22/02/2004 Chris Miller
; Bug in 'getbit' sub reported. The variable 'keys' was
; being returned in w instead of 'count'
; Port B is altered by loading the port register with 0x00
; and changing the TRIS register. Making a bit an output will
; force the bit to go low. The inputs are pulled high by the
; internal weak pullups
;
; SET READBACK KEY
; RB3 RB2 RB1 RB0 RB3 RB2 RB1 RB0
; 1 1 1 0 1 1 0 0 *
; 1 0 0 0 0
; 1 0 1 0 #
; 1 1 0 1 1 1 0 0 7
; 1 0 0 1 8
; 1 0 0 0 9
; 1 0 1 1 1 0 0 0 4
; 1 0 0 1 5
; 1 0 1 0 6
; 0 1 1 1 0 1 0 0 1
; 0 0 0 1 2
; 0 0 1 0 3list p=16f84
includekeys equ 0x10 ; current state of row
count equ 0x11 ; counter
keycode equ 0x12 ; number of button pressed
org 0
goto start
org 5 ; avoid interupt vector
start: bsf STATUS,RP0 ; change to bank 1
bcf OPTION_REG,NOT_RBPU ; enable pull ups on port b
clrf TRISA ; all outputs on port a
movlw 0x0f
movwf TRISB ; RB0 to RB3 inputs
bcf STATUS,RP0 ; change back to bank 0
clrf PORTA ; set all outputs low
clrf PORTBmain: call scan ; scan keyboard
movf keycode,W ; put keycode into w
xorlw 0xff ; is the returned number 255?
btfsc STATUS,F ; if so then no key pushed
goto main ; scan again
movf keycode,W ; put key number back into w
movwf PORTA ; output result on port akeyoff: call scan ; wait for user to release key
movf keycode,W ; put key number into w
xorlw 0xff ; is the returned number 255?
btfss STATUS,Z
goto keyoff ; no, keep scanning keyboard
goto main ; yes, start againscan: movlw 0xff
movwf keycode ; default to 0xff if no key pushed
movlw B'00001110'
bsf STATUS,RP0 ; bank 1
movwf TRISB ; turn B0 to an output (low)
bcf STATUS,RP0 ; bank 0
movf PORTB,W ; get port b state
andlw 0x0f ; mask lower nibble
movwf keys ; save result
xorlw B'00001110' ; check for no change
btfsc STATUS,Z
goto row2 ; try next row
call getbit ; find position of first set bit
call table1 ; translate to a key number
movwf keycode ; save result
returnrow2: movlw B'00001101'
bsf STATUS,RP0 ; bank 1
movwf TRISB ; turn B1 to an output (low)
bcf STATUS,RP0 ; bank 0
movf PORTB,W ; get port b state
andlw 0x0f ; mask lower nibble
movwf keys ; save result
xorlw B'00001101' ; check for no change
btfsc STATUS,Z
goto row3 ; try next row
call getbit ; find position of first set bit
call table2 ; translate to a key number
movwf keycode ; save result
returnrow3: movlw B'00001011'
bsf STATUS,RP0 ; bank 1
movwf TRISB ; turn B2 to an output (low)
bcf STATUS,RP0 ; bank 0
movf PORTB,W ; get port b state
andlw 0x0f ; mask lower nibble
movwf keys ; save result
xorlw B'00001011' ; check for no change
btfsc STATUS,Z
goto row4 ; try next row
call getbit ; find position of first set bit
call table3 ; translate to a key number
movwf keycode ; save result
returnrow4: movlw B'00000111'
bsf STATUS,RP0 ; bank 1
movwf TRISB ; turn B3 to an output (low)
bcf STATUS,RP0 ; bank 0
movf PORTB,W ; get port b state
andlw 0x0f ; mask lower nibble
movwf keys ; save result
xorlw B'00000111' ; check for no change
btfsc STATUS,Z
return
call getbit ; find position of first set bit
call table4 ; translate to a key number
movwf keycode ; save result
returngetbit: clrf count ; initialise counter
loop: btfsc keys,0 ; test bit zero
goto found
incf count,F ; add 1 to count
rrf keys,F ; move to next bit
goto loop ; try again
found: movf count,W ; put count into w for lookup table
returntable1: addwf PCL,F ; lookup table to convert number returned...
retlw 0xff ; dummy
retlw 0x0b ; #
retlw 0x0a ; *
retlw 0x00 ; 0table2: addwf PCL,F
retlw 0x08 ; 8
retlw 0xff ; dummy
retlw 0x07 ; 7
retlw 0x09 ; 9table3: addwf PCL,F
retlw 0x05 ; 5
retlw 0x06 ; 6
retlw 0xff ; dummy
retlw 0x04 ; 4table4: addwf PCL,F
retlw 0x02 ; 2
retlw 0x03 ; 3
retlw 0x01 ; 1end
