Micro Controller Basics

8/4/2019 Micro Controller Basics

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Microcontroller And InterfacingMicrocontroller And Interfacing

KantipurKantipur Engineering CollegeEngineering Collegeamra su e ec.e u.npamra su e ec.e u.np

11Samrat SubediSamrat Subedi

[email protected]@gmail.com



Contents:Contents: Introductory ConceptIntroductory Concept

-- Introduction to Embedded SystemIntroduction to Embedded System

-- ,,

-- Introduction to Top View SimulatorIntroduction to Top View Simulator

Basic inputs and outputsBasic inputs and outputs

Interfacing Seven segment DisplayInterfacing Seven segment Display

Keypad InterfacingKeypad Interfacing as cs o an ts nter ac ngas cs o an ts nter ac ng

Timer and CounterTimer and Counter

Interrupt HandlingInterrupt Handling

Introduction to ProteusIntroduction to Proteus





Wh do we need to learnWh do we need to learnMicroprocessors/controllers?Microprocessors/controllers?

The microprocessor is the core of

Nowadays many communication, digital

controlled by them.

components he needs, ways to reduceproduction costs and product reliable..





The necessary tools for aThe necessary tools for amicroprocessor/controllermicroprocessor/controller

I/O: Input /Output

Memory: RAM & ROM Timer

Interrupt

Serial Port

Parallel Port





Microprocessors:Microprocessors:

CPU for Com uters

General-purpose microprocessor

No RAM, ROM, I/O on CPU chip itself Example：Intel’s x86, Motorola’s 680x0

CPU Data BusMany chips on mother’s board

General-

Purpose

Micro-RAM ROM I/O

PortTimer

Serial

COM

processor

Address Bus

enera - urpose croprocessor ystem





Microcontroller :

A smaller computer

On-chip RAM, ROM, I/O ports...

’ ’ ’, ,

RAM ROMCPU

A single chip

I/O

PortTimer

SerialCOM

PortMicrocontroller





.

croprocessor

CPU is stand-alone, RAM,

ROM, I/O, timer are separate

crocon ro er

• CPU, RAM, ROM, I/O and

timer are all on a single chip

designer can decide on the

amount of ROM, RAM and

I/O orts.

• fix amount of on-chip ROM,

RAM, I/O ports

•

expansive

versatility

,

power and space are critical

• single-purpose

general-purpose





application. An embedded product uses a microprocessor or microcontroller to do

one as on y.

In an embedded system, there is only one application software that is

typically burned into ROM.

Example：printer, keyboard, video game player





Three criteria in Choosin a Microcontroller

.

effectively• speed, the amount of ROM and RAM, the number of I/O ports

an mers, s ze, pac ag ng, power consump on

• easy to upgrade

• cost er unit

2. availability of software development tools

• assemblers, debuggers, C compilers, emulator, simulator,

3. wide availability and reliable sources of the microcontrollers.





External interru ts

On-chip

RAM

On-chip

ROM for

programInterrupt

Control

Timer 1

Timer/Counter

Counter

In uts

CPU

4 I/O PortsSerial

PortOSCBus

Control

TxD RxDP0 P1 P2 P3

ress a a









Pin Description of the 8051Pin Description of the 8051

12

4039

P1.0P1.1

VccP0.0(AD0)

3

456

38

373635

P1.2

P1.3P1.4P1.5

P0.1(AD1)

P0.2(AD2)P0.3(AD3)P0.4(AD4)

8051

89

1011

3332

3130

.P1.7RST

(RXD)P3.0(TXD)P3.1

.P0.6(AD6)P0.7(AD7)

EA/VPPALE/PROG12131415

29282726

(T0)P3.4(T1)P3.5

(INT0)P3.2(INT1)P3.3

PSENP2.7(A15)P2.6(A14)P2.5(A13)

17181920

24232221

XTAL2XTAL1

GND

(RD)P3.7. .

P2.3(A11)P2.2(A10)P2.1(A9)P2.0(A8)





Feature of 8051Feature of 8051

Eight bit CPU with register A and B

t rogram ounter

Internal Ram of 128 bytes

4 Kb Flash Memory

4 I/O Ports

Two 16 bit Timer (T0 and T1)

Six Interrupts

… 1313

Samrat SubediSamrat [email protected]@gmail.com



Pins of 8051Pins of 8051（1/41/4））

– Vcc provides supply voltage to the chip.

– The voltage source is +5V.

GND（pin 20）：ground XTAL1 and XTAL2（pins 19,18）





Fi ur XTAL nn i n 51Fi ur XTAL nn i n 51

Using a quartz crystal oscillator

C2

We can observe the frequency on the XTAL2 pin.

30pF

XTAL2

1

30pF

XTAL1

GND





（）（）

（）：）：

– It is an input pin and is active high（normally

）.

The high pulse must be high at least 2 machine cycles.

– -

Upon applying a high pulse to RST, the

microcontroller will reset and all values in registers

will be lost.





--..Vcc

10 uF

+

30 pF

11.0592 MHz

EA/VPPX1

19

30 pF

.X2

RST

18

1717Samrat SubediSamrat [email protected]@gmail.com



（）（）

p n ex erna access

– There is no on-chip ROM in 8031 and 8032 .

–

stored externally.

– /PSEN＆ ALE are used for external ROM.– For 8051, /EA pin is connected to Vcc.

– “/” means active low.

/PSEN（pin 29）：program store enable– This is an output pin and is connected to the OE pin of the

.




（）（）

– It is an output pin and is active high.– 8051 ort 0 rovides both address and data.

– The ALE pin is used for de-multiplexing the address

and data by connecting to the G pin of the 74LS373atc .

I/O port pins

– , , , .– Each port uses 8 pins.

– - ..




The 8051 has four I/O orts

– Port 0（pins 32-39）：P0（P0_0～P0_7）– Port 1（pins 1-8）：P1（P1_0～P1_7）

– Port 2 pins 21-28 ：P2 P2_0～P2_7

– Port 3（pins 10-17）：P3（P3_0～P3_7）

–

Named P0_X（X=0,1,...,7）, P1_X, P2_X, P3_X

Ex：P0_0 is the bit 0（LSB）of P0

Ex：P0_7 is the bit 7 MSB of P0 These 8 bits form a byte.

- .⌦




Each in of I/O orts

– Internal CPU bus：communicate with CPU– A D latch store the value of this pin

a c s con ro e y r e o a c

– Write to latch＝1：write data into the D latch

– 2 Tri-state buffer： TB1: controlled by “Read pin”

– Read pin＝1：really read the data present at the pin

TB2: controlled b “Read latch”

– Read latch＝1：read value from internal latch

– A transistor M1 gate

a e= : open

Gate=1: close2121Samrat SubediSamrat [email protected]@gmail.com



D LatchD Latch::




Vcc

Load(L1)

Read latchTB2

D QInternal CPU

bus

P1.X

pinP1.X

Clk QWrite to latch M1

Read pin

TB1

⌦P0.x

8051 IC2323Samrat SubediSamrat [email protected]@gmail.com



“ ”“ ” ..

Vcc

Load(L1)

Read latch

2. output pin isTB2

D QInternal CPU

bus

P1.X

pinP1.X

1. write a 1 to the pin1

Clk QWrite to latch M10 ou pu

Read pin

TB1




“ ”“ ” ..

Vcc

Load(L1)

Read latch

2. output pin isTB2

D QInternal CPU

bus

P1.X

pinP1.X

1. write a 0 to the pin0

Clk QWrite to latch M11 ou pu

Read pin

TB1




“ ”“ ”

Vcc

Load(L1)

Read latch 2. MOV A,P1

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

P1,#0FFH

TB2

D QInternal CPU bus P1.X pin

P1.X

1 1


Read pin

3. Read in=1 Read latch=0

TB1

8051 ICWrite to latch=1




“ ”“ ”

Vcc

Load(L1)

Read latch

2. MOV A,P1external pin=Low1. write a 1 to the pin

TB2

D QInternal CPU bus P1.X pin

P1.X

,

1 0


Read pin

3. Read in=1 Read latch=0

TB1

8051 ICWrite to latch=1




-, , .

– P1, P2, and P3 are not open drain. -

connects to Vcc inside the 8051.

– P0 is open drain.– Compare the figures of P1.X and P0.X.

However, for a programmer, it is the same to program

P0, P1, P2 and P3. All the ports upon RESET are configured as output.




Read latch

TB2

D QInternal CPU

bus

P0.X

pinP1.X


Read pin

TB1

P1.x




Port 0 with PullPort 0 with Pull--U ResistorsU Resistors

10 K

P0.0P0.1

P0.2

DS5000P o

r t .

P0.4P0.5P0.6

8951 0

.





Port 3 Alternate FunctionsPort 3 Alternate FunctionsPinPinFunctionFunctionP3 BitP3 Bit

1010RxDRxDPP33..00

1212INT0INT0P3.2P3.2

..

1515TT11P3.5P3.5

1414T0T0P3.4P3.4

..

1717RDRDP3.7P3.7

1616WRWRP3.6P3.6





0000PCReset ValueRegister

0000B

0000ACC

0007SP

0000PSW

0000DPTR

..⌦





Registers

A

B

R1

R2

DPH DPL

PC

DPTR

PC

R3

R4

R5

Some 8051 16-bit Register

R7

R6

Some 8-bitt Registers of the

8051





ROM memory map in 8051 family

0000H 0000H 0000H

1FFFH8751

AT89C518752

AT89C52





memory space a ocat on n t e 8051

Scratch pad RAM

30H

2FH

Bit-Addressable RAM

20H

1FH

17H

18HRegister Bank 3

10H0FH

07H

08H(Stack) Register Bank 1

eg s er an

00HRegister Ban 0





The re ister used to access

the stack is called SP (stack

pointer) register.

7FH

Scratch pad RAM

The stack pointer in the 8051is only 8 bits wide, which

means that it can take value

2FH

20H

Bit-Addressable RAM

00 to FFH. When 8051powered up, the SP registercontains value 07.

1FH

17H

10H

0FH

18H

Register Bank 2

Register Bank 3

07H

08H

00HRegister Bank 0





Writing Simple ProgramWriting Simple Program#include<at#include<at8989xx5151.h>.h>

void delay(void delay(intint a)a)

floatfloat ii;;

for (for (ii==00;i<;i<100100*a ;*a ;ii++ );++ );

void main()void main()

{{

while(while(11))

PP11_ _11=!P=!P11_ _11;;delay(delay(1010););

Save asSave as ---- c:c:\ \program filesprogram files\ \SDCCSDCC\ \bin>bin>led. hled. h3737

Samrat SubediSamrat [email protected]@gmail.com



..

:: program esprogram es n>n>pac xpac x e . x> e . exe . x> e . ex

you will Seeyou will See

packihxpackihx: read: read 107107 lines, wrotelines, wrote 5858: OK.: OK.



And thenAnd then



And thenAnd then

12000













4242

Samrat SubediSamrat Subedi




4343





4444





4545



Try thisTry this



Try thisTry this..

void delay(void delay(intint a)a)

{{

for (for (ii==00;i<;i<100100*a ;*a ;ii++ );++ );

}}

{{

char in=char in=00xx0404;;

==

while(while(11))

{{

++++

delay(delay(2020););

PP00=in;=in;

}}

4646



LED ON I/O PORTSLED ON I/O PORTS



LED ON I/O PORTSLED ON I/O PORTS'

above 1mA so the LED will be verydim.

he LED will conduct heavily at about 2Vand the extra 3V has to be dropped in the

.dissipation in the TTL or the LED fails.

.calculated by assuming its voltage is about 2.5V and theTTL output is 0.9V. For 2.2V LED, 1.9V is across the

.

(1.9/220). For 1.7V LED, 2.4V is across the resistor so itwould limit the current to 10.9mA (2.4/220). The resistorshould not less than 100ohm or the LED would fail.

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Micro Controller Basics