Microcontroller 8051 training

Microcontroller 8051
Training
-Pradip Bhandari
Tuesday, July 14, 2015 Robotics Club, IOE, WRC 1

I assume every body is familiar with Basic C programming
Everybody is well known about basic Digital gates
Everybody knows Number Systems
Everybody has concept of basic electronics including RAM and
ROM memory
And all are expert in using computer

Contents
 Introduction
 Block Diagram and Pin Description of the 8051
 Environment setup (Proteus and Keil)
 Introduction to Proteus
 Simple LED Blink
 DEMO
 LCD Programming
 DEMO

Introduction
Microcontroller
• CPU, RAM, ROM, I/O and timer are all on a single chip
• fix amount of on-chip ROM, RAM, I/O ports
• for applications in which cost, power and space are critical
• single-purpose
RAM ROM
I/O
Port
Timer
Serial
COM
Port
Microcontroller
CPU
A single chip

Block Diagram
CPU
On-chip
RAM
On-chip
ROM for
program
code
4 I/O Ports
Timer 0
Serial
PortOSC
Interrupt
Control
External interrupts
Timer 1
Timer/Counter
Bus
Control
TxD RxDP0 P1 P2 P3
Address/Data
Counter
Inputs

Feature 8051 8052 8031
ROM (program space in bytes) 4K 8K 0K
RAM (bytes) 128 256 128
Timers 2 3 2
I/O pins 32 32 32
Serial port 1 1 1
Interrupt sources 6 8 6
Features and Comparison 8051

Pin Description of the 8051
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
40
39
38
37
36
35
34
33
32
31
30
29
28
27
26
25
24
23
22
21
P1.0
P1.1
P1.2
P1.3
P1.4
P1.5
P1.6
P1.7
RST
(RXD)P3.0
(TXD)P3.1
(T0)P3.4
(T1)P3.5
XTAL2
XTAL1
GND
(INT0)P3.2
(INT1)P3.3
(RD)P3.7
(WR)P3.6
Vcc
P0.0(AD0)
P0.1(AD1)
P0.2(AD2)
P0.3(AD3)
P0.4(AD4)
P0.5(AD5)
P0.6(AD6)
P0.7(AD7)
EA/VPP
ALE/PROG
PSEN
P2.7(A15)
P2.6(A14)
P2.5(A13)
P2.4(A12)
P2.3(A11)
P2.2(A10)
P2.1(A9)
P2.0(A8)
8051
(8031)
PORT 0
PORT 2
PORT 1
PORT 3

Pins of 8051（1/4）
• Vcc（pin 40）：
• Vcc provides supply voltage to the chip.
• The voltage source is +5V.
• GND（pin 20）：ground
• XTAL1 and XTAL2（pins 19,18）：
• These 2 pins provide external clock.
• Way 1：using a quartz crystal oscillator
• Way 2：using a TTL oscillator
• Example 4-1 shows the relationship between XTAL and the
machine cycle.

XTAL Connection to 8051
C2
30pF
C1
30pF
XTAL2
XTAL1
GND
• Using a quartz crystal oscillator
• We can observe the frequency on the XTAL2 pin.

XTAL Connection to an External Clock
Source
N
C
EXTERNAL
OSCILLATOR
SIGNAL
XTAL2
XTAL1
GND
• Using a TTL oscillator
• XTAL2 is unconnected.

Pins of 8051（2/4）
• RST（pin 9）：reset
• It is an input pin and is active high（normally low）.
• The high pulse must be high at least 2 machine cycles.
• It is a power-on reset.
• Upon applying a high pulse to RST, the microcontroller will
reset and all values in registers will be lost.
• Reset values of some 8051 registers
• Way 1：Power-on reset circuit
• Way 2：Power-on reset with debounce

Power-On RESET Circuit
30 pF
30 pF
8.2 K
10 uF
+
Vcc
11.0592 MHz
EA/VPP
X1
X2
RST
31
19
18
9

Power-On RESET with Debounce
EA/VPP
X1
X2
RST
Vcc
10 uF
8.2 K
30 pF
9
31
Tuesday, July 14, 2015 Robotics Club, IOE, WRC 13

Pins of 8051（3/4）
• /EA（pin 31）：external access
• There is no on-chip ROM in 8031 and 8032 .
• The /EA pin is connected to GND to indicate the code is 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 ROM.
• See Chapter 14.

Pins of 8051（4/4）
• ALE（pin 30）：address latch enable
• It is an output pin and is active high.
• 8051 port 0 provides both address and data.
• The ALE pin is used for de-multiplexing the
address and data by connecting to the G
pin of the 74LS373 latch.
• I/O port pins
• The four ports P0, P1, P2, and P3.
• Each port uses 8 pins.
• All I/O pins are bi-directional.

Pins of I/O Port
• The 8051 has four I/O ports
• Port 0 （pins 32-39）：P0（P0.0～P0.7）Bit address (0x80~0x87)
• Port 1（pins 1-8）：P1（P1.0～P1.7） Bit address (0x90~0x97)
• Port 2（pins 21-28）：P2（P2.0～P2.7） Bit address (0xA0~0xA7)
• Port 3（pins 10-17）：P3（P3.0～P3.7） Bit address (0xB0~0xB7)
• Each port has 8 pins.
• 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 port can be used as input or output (bi-direction).


PORT P0 (PIN 39 TO 32)
Port P0 has got three functionalities.(I/O port, lower order address(A0 to A7)
and data (D0 to D7).
It can be used for input or output , each pin must be connected externally to a
10K ohm pull-up resistor.
ALE indicates if P0 has address or data
When ALE=0, it provides data D0-D7
When ALE=1, it has address A0-A7

Pull Up Resistor
• Pull-up resistor pulls the voltage of the signal it is connected to
towards its voltage source level
• Pull-up resistor ensures that the wire is at a defined logic level even if
no active devices are connected to it
• At reset condition the port zero will be at floating
condition ,i.e no 0 no 1 something other
state which we cannot predict so to ensure
proper logic level we use Pull-up resistor

Port P1 is simple I/O port .
Internal pull up resistor is provided.
PORT P2(PIN 21 TO 28)
Port P2 has dual functionality.( I/o port and higher order address(A8
to A15)
Port 2 must be used along with P0 to provide the 16-bit address for
the external memory.
 Internal pull up resistor is provided.

Port 3 can be used as input or output.
Port 3 does not need any pull-up resistors.
Port 3 has the additional function of providing some extremely important
signals.

Environment Setup
Proteus Installation (Proteus 8.1 SP1)(Recommend to use latest version)
 1. Exact the provided package
 2. Open LICENSE.EXE
 3. Change the attribute of Key.lxk to no hidden and no readonly
 4. Browse for key -> Select Key.lxk
 5. Install key
 6. Close LICENSE.EXE
 7. Install Proteus 8.1 SP1.exe
 8. Do not run after installation
 9. Copy "BIN" To Installation Folder (C:Program Files (x86)Labcenter ElectronicsProteus 8 Professional)
 10. Copy "MODELS" To ProgramData (C:ProgramDataLabcenter ElectronicsProteus 8 Professional)
 11. Run Proteus and enjoy!

Keil Installation
• I recommend to use latest version of keil(version 4 for 51)
• Install the Provided Keil software(trial version or cracked )
• Provide the basic information
• Done

Proteus
Isis should be highlighted (Clickable)
Click it to open to initiate design

1
2
3
1. Component mode, Click here
to enable Component mode
so that we can browse any
basic component from 2(pick
device)
2. Pick Device, Click here to pick
any require component into
our workspace
3. Terminal Nodes, terminal
nodes like Ground, Power
source etc is available over
here

Create a basic Led Blink Circuit
1
2
1. Click Component mode 3. Type at89c52
2. Click pick device 4. Select the first one
3
4

Pick the LED
1
2
3
4
1. Type Keyword led
2. Select Optoelectronics in Category
3. Select LEDs in sub-category
4. Select LED-RED or LED-GREEn or LED-
BLUE in Results

Led blink circuit
1. Pick At89c52
microcontroller from
device selector
2. Also pick led as shown in
figure and wire them
3. Pick a ground from
terminal nodes
4. Zoom the workspace as
per your easiness
5. Now save your work and
give it a name Blink
6. Now its time to write
program in keil

LED blink Program in Keil using C
1. Open keil
2. Goto Project>New uvision Project> give it a name as Blink (file
extension not needed)and save it
3. From CPU Database select Atmel > AT89C52 press ok and click No
to not to copy start up files
4. Goto file menu and select new(or press ctrl + N)
5. Save it as Blink.c (don’t forget to include file extension as .c)
6. Under project > Target 1 > Source group 1 add Blink.c (double click
Source group 1 to add blink.c)

Creating HEX file
6. Under Flash menu goto Configure Flash Tools…
7. 1
2
3
4
5
1. Select Target
2. Enter Xtal value as 12.0
3. Check Use On-chip ROM
4. Select Output
5. Check Create HEX File
Click OK

Simple LED BLINk.C
#include<reg51.h>
sbit out = P2^0;
void msdelay(unsigned int);
void main()
{
while(1)
{
out=1;
msdelay(500);
out=0;
msdelay(500);
}
}
void msdelay(unsigned int time)
{
unsigned int i,j;
for(i=0;i<=time;i++)
for(j=0;j<=1275;j++);
}
1.To Address Port we use sfr or #define keyword
sfr ldata = P1; // P must be Capital
sfr ldata = 0x90;
#define ldata P1 // no equals to, no semicolon
2. To Address A single bit of a Port we use sbit keyword
sbit out = P2^0; // it indicates P2.0
sbit enable = P2^1; // P must be Capital
sbit buttonChech = P2^2;
3. At initial stage or at reset condition the output of
each port or port bit(pin) will be 1(high)

Compile and Build
1
2
3
1. Make a Habit to save your
work all the time, press
(Ctrl+S) to save
2. Compile or Translate, Click it
to compile your code to
check errors and
warning(Ctrl+f7)
3. Press Build or Rebuild to
generate HEX file

Uploading HEX File
1
2
3
1. Double Click at Microcontroller
AT89C52 to open Edit
Component Dialog Box
2. Browse for HEX file that you
created earlier
3. Press Ok
4. Run Your Simulation
4

DEMO

To make a port or single pin as an input we need to declare it as HIGH or 1
#include<reg51.h>
sbit out = P2^0;
sbit in = P2^1;
void msdelay(unsigned int);
void main()
{
in = 1;
P2=0;
while(1)
{
if( in == 1){
out=1;
}
else {
out=0;
}
}
}
void msdelay(unsigned int time)
{
unsigned int i,j;
for(i=0;i<=time;i++)
for(j=0;j<=1275;j++);
}
Search Button in
Component search box

Liquid Crystal Display (LCD):-
LCD is finding widespread use replacing LEDs because
 The declining prices of LCD
 The ability to display numbers, characters and graphics
Ease of programming for characters and graphics

Pin Descriptions for LCD
Pin Symbol I/O Descriptions
1 VSS ----- Ground
2 VCC ----- +5 v power supply
3 VEE ----- Power supply to contrast
4 RS I Register Select( 0 for command register and 1
for data register)
5 __
R /W
I 1 for Read
0 for write
6 E I/O Enable
7-14 DB0-DB7 I/O The 8-bit data bus
15 LED + ----- Usually Connected t0 +5v of power supply
16 LED- ----- Connected to Ground

Instruction VS Data
• Instruction Register (IR) and Data Register (DR)
• Instruction is a Command, Data is a displaying Value
• There are two 8-bit registers in Our LCD controller IC, Instruction and
Data register. Instruction register corresponds to the register where
you send commands to LCD e.g LCD shift command, LCD clear, LCD
address etc. and Data register is used for storing data which is to be
displayed on LCD.
• Only the instruction register (IR) and the data register (DR) of the LCD
can be controlled by our 8051 microcontroller

LCD PROTEUS SIMULATION
1.Lcd is named as LM016L in Component
Mode Pick Device i.e Library
2. Connect P2.0~P2.7 of microcontroller to
D0~D7 of LCD respectively
3. Connect P3.0 to RS, P3.1 to RW and P3.2
to E

Before using the LCD for display purpose, LCD has to be initialized either
by the internal reset circuit or sending set of commands to initialize the
LCD. It is the user who has to decide whether an LCD has to be initialized
by instructions or by internal reset circuit. we will dicuss both ways of
initialization one by one.
We need to initialize LCD to define type of LCD, Cursor Position, Home
Location etc
Type includes like 16x2 or 14x1 or 20x2 etc

Some Points to note while Programming
A high to low pulse should be provided in an enable pin for Write
Operation
A low to high pulse should be provided in an enable pin for Read
Operation
Bit D7 of LCD is busy flag which can be used to check if LCD is busy in its
own internal operation
Busy flag can be read when R/W =1 and RS=0 and a L to H pulse in enable
pin
NOTE:- It is recommended to check busy flag before writing any data to LCD.

LCD BUSY CHECK (BF-FLAG)
• Busy Flag is an status indicator flag for LCD. When we send a
command or data to the LCD for processing, this flag is set (i.e BF =1)
and as soon as the instruction is executed successfully this flag is
cleared (BF = 0). This is helpful in producing and exact amount of
delay. for the LCD processing.
• To read Busy Flag, the condition RS = 0 and R/W = 1 must be met and
The MSB of the LCD data bus (D7) act as busy flag. When BF = 1
means LCD is busy and will not accept next command or data and BF
= 0 means LCD is ready for the next command or data to process.

BUSY CHECK
void lcdbusy()
{
busy=1; // declaring D7 of LCD as input to check busy flag
rw=1;
rs=0;
while(busy==1)
{
en=0;
msdelay(1);
en=1;
}
return;
}

Sending Command To LCD
void lcdcmd(unsigned char value)
{
lcdbusy(); //Wait for LCD to process the command
ldata=value; //Function set: 2 Line, 8-bit, 5x7 dots
rs=0; //Selected command register
rw=0; //We are writing in instruction register
en=1; //Enable H->L
msdelay(1);
en=0; //Enable H->L
return;
}

LCD Command Codes

Sending Data To LCD
void lcddata(unsigned char value)
{
lcdbusy(); //Wait for LCD to process the command
ldata=value; //Function set: 2 Line, 8-bit, 5x7 dots
rs=1; //Selected data register
rw=0; //We are writing in data register
en=1; //Enable H->L
msdelay(1);
en=0; //Enable H->L
return;
}
// we will pass the character to display as argument to function

Sending String Data To LCD
void lcdstr(unsigned char msg[15]) //to print string in lcd
{
unsigned char i=0;
while(msg[i]!='$')
{
if(i>16)
{
msdelay(10);
lcdcmd(0x07); //shift display to left
}
if(msg[i]==' ')
msdelay(50);
if(i==15)
lcdcmd(0x07);
lcddata(msg[i]);
i++;
}
}Tuesday, July 14, 2015 Robotics Club, IOE, WRC 46

SELECTING FIRST AND SECOND ROW
void lcdfirst()
{
lcdcmd(0x38);
lcdcmd(0x0e);
msdelay(50);
lcdcmd(0x01);// clear
lcdcmd(0x06);
lcdcmd(0x80);
}
void lcdsecond()
{
lcdcmd(0x38);
lcdcmd(0x0e);
msdelay(50);
lcdcmd(0x06);
lcdcmd(0xc0);
}

OVERALL PROGRAM FOR LCD

#include<reg51.h>
#define ldata P2 //lcd data
sbit rs=P3^0; //lcd signals
sbit rw=P3^1;
sbit en=P3^2;
sbit busy=P2^7;
void lcdbusy(); //to check if lcd is busy or not
void lcdcmd(unsigned char) ; // to give lcd commands
void lcddata(unsigned char); //to give data to the lcd
void lcdfirst(); // first line of lcd initialization
void lcdsecond(); // second line of lcd initialization
void lcdstr(unsigned char[]); // to display string
void msdelay (unsigned char);
void main()
{
P2=0;
P3=0;
while(1)
{
lcdfirst();
lcdstr("Hello");
msdelay(1000);
lcdsecond();
lcdstr("Pokhara1");
msdelay(1000);
}
}

void msdelay(unsigned char time)
{
unsigned int i,j;
for(i=0;i<time;i++)
for(j=0;j<=1275;j++);
}
void lcdbusy()
{
busy=1;
rw=1;
rs=0;
while(busy==1)
{
en=0;
msdelay(1);
en=1;
}
return;
}

void lcdcmd(unsigned char value)
{
lcdbusy();
ldata=value;
rs=0;
rw=0;
en=1;
msdelay(1);
en=0;
return;
}
void lcddata(unsigned char value)
{
lcdbusy();
ldata=value;
rs=1;
rw=0;
en=1;
msdelay(1);
en=0;
return;
}

void lcdfirst()
{
lcdcmd(0x38); //2 lines and 5x7 matrix
lcdcmd(0x0e);
msdelay(50); //cursor blink
lcdcmd(0x01); //clear display screen
lcdcmd(0x06); //shift cursor to right
lcdcmd(0x80);
}
void lcdsecond()
{
lcdcmd(0x38); //2 lines and 5x7 matrix
lcdcmd(0x0e);
msdelay(50); //cursor blink
lcdcmd(0x06); //shift cursor to right
lcdcmd(0xc0);
}

void lcdstr(unsigned char msg[]) //to print string in lcd
{
unsigned char i=0;
while(msg[i]!='0')
{
if(i>16)
{
msdelay(10);
lcdcmd(0x07);
}
if(msg[i]==' ')
msdelay(50);
if(i==15)
lcdcmd(0x07);
lcddata(msg[i]);
i++;
}
}

ANY QUESTION?

Microcontroller 8051 training

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