Department of Computer Scien

ce and Information Engineering

National Cheng Kung University, TAIWAN

HANEL

ROTATE INSTRUCTIONAND DATA

SERIALIZATIONSerializing Data

(cont’)

‰Transfer a byte of data serially by

¾Moving CY to any pin of ports P0

– P3

¾Using rotate instructionWrite a program to transfer value

41H serially (one bit at a time)

via pin P2.1. Put two highs at the start and end of the data. Send the byte LSB first.Solution:

MOV A,#41HSETB P2.1 ;highSETB P2.1 ;highMOV R5,#8

AGAIN: RRC A

MOV P2.1,C ;send CY to P2.1DJNZ R5,HERESETB P2.1 ;highSETB P2.1 ;high

P2.1

CY

Register A

D7

D0

Pin