The 8051 Microcontroller and Embedded

Department of Computer Scien

ce and Information Engineering

National Cheng Kung University, TAIWAN

HANEL

OTHER MODES OF THE 82558255 in Mode 1:

I/O With Handshaking

Capability

(cont

’)

PC 4,5 8255 Mode 1 Output Diagram

Port A Output Port B Output

OBFAACKA INTRA OBFBACKB INTRB

Port A withHandshake Signals Port B withHandshake Signals

Control Word – Mode 1 Output

x 0

1

1/0 0

(^10)
1
D0D1
D2D3
D4D5
D6D7
Port B OutputPort B Mode 1
Port B Output
Port A OutputPort A Mode 1
Port A Mode 1I/O Mode
PC 4,5 1=Input,0=Output
Status Word – Mode 1 Output
D0D1
D2D3
D4D5
D6D7
INTRB
INTRAINTEB
INTEA
OBFB
OBFA
I/OI/O
INTEA is controlled by PC6 in BSR mode.INTEB is controlled by PC2 in BSR mode.
PA7PA0PC7PC6 PC3 PC1PC2 PC0PB7PB0
INTEA INTEB WR