AN665

DS00665A-page 12

ã 1997 Microchip Technology Inc.

006C 032D

00313

rrf

BUFFER6,F

006D 032C

00314

rrf

BUFFER5,F

006E 032B

00315

rrf

BUFFER4,F

006F 032A

00316

rrf

BUFFER3,F

0070 0329

00317

rrf

BUFFER2,F

0071 0328

00318

rrf

BUFFER1,F

0072 0327

00319

rrf

BUFFER0,F

00320

00321 ; compare duty cycle, to skip preamble

0073 0CE0

00322

movlw

0E0

; test duty cycle

0074 0152

00323

andwf

TIMELO,W

; delta >200us? (32 cycles)

0075 0643

00324

btfsc

STATUS,Z

0076 0A4A

00325

goto

Receive

; no! itÕs a preamble

00326

0077 02EF

00327

decfsz

BITCOUNT,F

; loop to completion

0078 0A5B

00328

goto

RNextBit

0079 0800

00329

retlw

0

00330

00331 ;----------------------------------------------------------------------

00332 ;**********************************************************************

00333 ;*

Main loop

00334 ;*

set TRIS and option register

00335 ;*

wait for start (LED)

00336 ;*

disable keyboard

00337 ;*

receive new hopping code

00338 ;*

send 16 hex digits

00339 ;*

wait transmission end

00340 ;*

loop

00341 ;**********************************************************************

00342 ;

007A

00343 Main

007A 0C04

00344

movlw

bÕ00000100Õ ; set switch ON

007B 0026

00345

movwf

GPIO

007C 0CFB

00346

movlw

MASKDEF

; init port

007D 0006

00347

tris

GPIO

007E 0C00

00348

movlw

0

007F 0002

00349

option

00350

0080 06A6

00351

btfsc

LED

; wait for Led output fall

0081 0A7A

00352

goto

Main

00353

0082

00354 Disable

0082 0066

00355

clrf

GPIO

; send disable kb

00356

; SWITCH = LOW

00357

0083 094A

00358

call

Receive

; gets the new hopping code

00359

00360 ;----------------------------------------------------------------------

00361 ; emulate a keyboard and send data as a sequence of 16 key

00362 ; pressed and released, one each hex digit

00363 ;

0084 0C08

00364

movlw

.8

; 8 byte from the buffer

0085 0030

00365

movwf

BYTECOUNT

0086 0C07

00366

movlw

BUFFER0

; init pointer

0087 0024

00367

movwf

FSR

00368

0088

00369 KEYL

0088 0200

00370

movf

INDF,W

; low nibble

0089 0E0F

00371

andlw

0F

008A 0902

00372

call

ScanCode

; encode hex nibble

008B 0035

00373

movwf

KEY

008C 0937

00374

call

SendKEY

; emulate key press

008D 091A

00375

call

Wait10ms

008E 0CF0

00376

movlw

BREAK

; emulate key release

008F 0937

00377

call

SendKEY

0090 0C01

00378

movlw

1