This presentation summarizes the Programmable Peripheral Interface 8255 chip. It includes an introduction to the PPI 8255, describing it as a general purpose programmable device used for data transfer between processors and I/O devices. It has 3 programmable I/O ports (PA, PB, and PC) that are operated in different modes like I/O modes and BSR mode based on the control word in the control word register. The presentation also includes a pin diagram showing the functions of the various pins, and a block diagram depicting the internal structure and data flow of the PPI 8255 chip.

1. WELCOME
TO MY
PRESENTATION
Presented By
Km. Zahid parvez
Roll:10
Batch:9th
3rd Year 2nd semester.
PUNDRA UNIVERSITY OF SCIENCE &
TECHNOLOGY(PUST)
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2. Presentation On
PROGRAMMABLE PERIPHERAL
INTERFACE (PPI) -8255
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3. Presentation Outline
 Introduction of PPI.
 Pin Diagram & Function of PPI 8255.
 Block Diagram of PPI 8255.
 I/O Mode
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4. PROGRAMMABLE PERIPHERAL
INTERFACE (PPI) -8255
• 8255 is a general purpose programmable device used for data transfer
between processorsand I/O device.
• It has 3 programmable I/O port (PA, PB & PC) and port operation
(IN/OUTport)is define by controlword in the controlword register.
• Port are operatedinmodes:
1. I/O modes:- Mode 0, Mode 1 and Mode2.
2. BSR (Bit Set/Reset)mode.
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5. PinDiagram&Function
1 40
2 39
3 38
4 37
5 36
6 35
7 34
8 33
9 8255 32
10 PPI 31
11 30
12 29
13 28
14 27
15 26
16 25
17 24
18 23
19 22
20 21
PA3
PA2
PA1
PA0
PA4
PA5
PA6
PA7
D0
D1
D2
D3
D4
D5
D6
D6
PC7
PC6
PC5
PC4
PC0
PC1
PC2
PC3
PB0
PB1
PB2
PB7
PB6
PB5
PB4
PB3
Vcc
WR`
RESET
RD`
CS`
Gnd
A1
A0
1. Port A (PA)
2. Port B (PB)
3. Port C (PC)
• Port A (PA7 – PA0) : 8pins.
• Port B (PB7 - PB0) : 8pins.
• Port C (Pc: Upper: PC7 – PC4) : 4pins.
• Port C (Pc: Lower: PC3 – PC0) : 4pins.
• Data Bus (D7- D0) :8pins.
• Control Signal : 6pins.
• Vcc and Gnd: 2pins.
Function
PA0-PA7 I/O  Port can be configured either input or outputby software.
 PAcan be programmed by mode 0 , mode 1, mode 2 .
 PB can be programmed by mode 0 and mode 1.
 PC can be programmed by bit set/reset operation.
PB0-PB7 I/O
PC0-PC7 I/O
D0-D7 I/O  Used for data transfer withMPU.
 Transfer of control words toPPI.
 Read status information from PPI.
CS` Input  Chips select input.
RD` Input  Read signal.
WR` Input  Write Signal
A0, A1 Input  Used to select port A, B, C and the control registers.
RESET Input  Used to clear control register
Vcc Power
Supply
 5V
Vss Power
Supply
 GND
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6. 8255BlockDiagram
DATA BUS
BUFFER
READ/WRITE
CONTROL
LOGIC
GROUP A
CONTROL
GROUP B
CONTROL
GROUP A
PORT A(8)
GROUP A
PORT C
UPPER (4)
GROUP B
PORT C
LOWER (4)
GROUP B
PORT B (8)
Bidirectional
Data Bus
D7 – D0
Power ----+5V
Supply ---Ground
RD`
WR`
A0
A1
Reset
CS`
8 Bit
Internal
Data Bus
I/O
PA7-PA0
I/O
PC7-PC4
I/O
PC3-PC0
I/O
PB7-PB0
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7. D7 D6 D5 D4 D3 D2 D1 D0
Group A
Port C Upper
1=Input
0=Output
Port A
1=Input
0=Output
Mode selection
00=mode 0
01=mode 1
1x=mode 2
Group B
Port C Lower
1=Input
0=Output
Port B
1=Input
0=Output
Mode selection
0=mode 0
1=mode 1
Mode set
1: i/o MODE
0: BSR mode
ForI/OMode:Thecontrol word mode format for I/O asshowninfigure
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