8051 ports

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Page 1: 8051 ports
Page 2: 8051 ports
Page 3: 8051 ports

A Pin of Port 1A Pin of Port 1

8051 IC

D Q

Clk Q

Vcc

Load(L1)

Read latch

Read pin

Write to latch

Internal CPU bus

M1

P1.X pinP1.X

TB1

TB2

P0.x

Page 4: 8051 ports

Writing “1” to Output Pin P1.XWriting “1” to Output Pin P1.X

D Q

Clk Q

Vcc

Load(L1)

Read latch

Read pin

Write to latch

Internal CPU bus

M1

P1.X pinP1.X

8051 IC

2. output pin is Vcc1. write a 1 to the pin

1

0 output 1

TB1

TB2

Page 5: 8051 ports

Writing “0” to Output Pin P1.XWriting “0” to Output Pin P1.X

D Q

Clk Q

Vcc

Load(L1)

Read latch

Read pin

Write to latch

Internal CPU bus

M1

P1.X pinP1.X

8051 IC

2. output pin is ground1. write a 0 to the pin

0

1 output 0

TB1

TB2

Page 6: 8051 ports

Reading “High” at Input PinReading “High” at Input Pin

D Q

Clk Q

Vcc

Load(L1)

Read latch

Read pin

Write to latch

Internal CPU bus

M1

P1.X pin

P1.X

8051 IC

2. MOV A,P1

external pin=High1. write a 1 to the pin MOV

P1,#0FFH

1

0

3. Read pin=1 Read latch=0 Write to latch=1

1

TB1

TB2

Page 7: 8051 ports

Reading “Low” at Input PinReading “Low” at Input Pin

D Q

Clk Q

Vcc

Load(L1)

Read latch

Read pin

Write to latch

Internal CPU bus

M1

P1.X pin

P1.X

8051 IC

2. MOV A,P1

external pin=Low1. write a 1 to the pin

MOV P1,#0FFH

1

0

3. Read pin=1 Read latch=0 Write to latch=1

0

TB1

TB2

Page 8: 8051 ports

A Pin of Port 0A Pin of Port 0

8051 IC

D Q

Clk Q

Read latch

Read pin

Write to latch

Internal CPU bus

M1

P0.X pinP1.X

TB1

TB2

P1.x

Page 9: 8051 ports

Port 0 with Pull-Up ResistorsPort 0 with Pull-Up Resistors

P0.0P0.1P0.2P0.3P0.4P0.5P0.6P0.7

DS5000

8751

8951

Vcc10 K

Port 0

Page 10: 8051 ports
Page 11: 8051 ports
Page 12: 8051 ports

Port 3 Alternate FunctionsPort 3 Alternate Functions

1717RDRDP3.7P3.7

1616WRWRP3.6P3.6

1515T1T1P3.5P3.5

1414T0T0P3.4P3.4

1313INT1INT1P3.3P3.3

1212INT0INT0P3.2P3.2

1111TxDTxDP3.1P3.1

1010RxDRxDP3.0P3.0

PinPinFunctionFunctionP3 BitP3 Bit