The 8051 Microcontroller and Embedded

Department of Computer Scien

ce and Information Engineering

National Cheng Kung University, TAIWAN

HANEL

OTHER MODES OF THE 8255

BSR

(Bit Set/Reset)Mode

(cont

’)

Example 15-7Program the 8255 in Figure 15-13 for the following.(a) Set PC2 to high.(b) Use PC6 to generate a squareSolution:(a)

MOV R0,#CNTPORTMOV A,#0XXX0101 ;control byteMOVX @R0,A

(b)AGAIN MOV A,#00001101B ;PC6=1

NOV R0,#CNTPROT

;load control port add

MOVX @R0,A ;make PC6=1ACALL DELAYACALL DELAYMOV A,#00001100B ;PC6=0ACALL DELAY

;time delay for low pulse

SJMP AGAIN