The 8051 Microcontroller and Embedded

Department of Computer Scien

ce and Information Engineering

National Cheng Kung University, TAIWAN

HANEL

PROGRAMMING THE 8255Connecting 8031/51 to

(^8255) (cont’)
Example 15-3 (cont’)(c)
MOV A,#90H ;(PA=IN, PB=OUT, PC=OUT)MOV DPTR,#1003H ;load
control register
;port address
MOVX @DPTR,A ;issue control wordMOV DPTR,#1000H ;PA addressMOVX A,@DPTR ;get data from PAINC DPTR ;PB addressMOVX @DPTR, A ;send the data to PBINC DPTR ;PC addressMOVX @DPTR, A ;send it also to PC