SUMMER TRAINING JULY 2012
EMBEDDED SYSTEM
(Microcontroller)
Submitted by:CHANDRAMOHAN SINGH
AMARJEET KUMAR
ABHISHEK KUMAR
Btech-ECE(5th sem)
CTIT
• The embedded system is a combination of computer hardware,
software additional electrical & mechanical parts
• A computer is used in such devices primarily as a means to simplify
the system design and to provide flexibility.
• Embedded systems employ the use of a RTOS (Real-Time
Operating System).
Block Diagram of Embedded System
Microcontroller
• A smaller computer.
• On-chip RAM, ROM, I/O ports...
• Example:- Motorola’s 6811, Intel’s 8051 and PIC 16X
CPU
RAM
ROM
A single chip
I/O Port Timer
Serial
COM
Port
Microcontroller
The 8051 Microcontroller :
•
The 8051 is the first microcontroller of
the MCS-51 family introduced by
Intel Corporation at the end of the
1970’s.
• The 8051 family characteristics:
○ The 8051 family characteristics:
○ 4K Bytes ROM
○ 128 Bytes RAM
○ two timer/counters (16 bit)
○ A serial port
○ 32 input/output port
○ Interrupt controller
8051 Internal Architecture
IC 8051 Pin Description
Voltage Supply
(+5V)
Ground
IC 8051 Pin Description
Port 0 from
Pin-39 to Pin-32
An 8-bit open drain
bidirectional port.
DUAL
FUNCTION
Used to access both
data and address
IC 8051 Pin Description
Port 1 from
Pin-1 to pin-8
8-bit bidirectional
I/O port with
internal pull-ups
IC 8051 Pin Description
Port 2 from
Pin-21 to pin-28
Used to access
address and I/O
IC 8051 Pin Description
P3.0 : RxD(serial input port)
P3.1 :TxD (serial output port)
P3.2 :INT0 (external interrupt 0)
P3.3 :INT1 (external interrupt 1)
P3.4 :T0 (timer 0 external input)
P3.5 :T1 (timer 1 external input)
P3.6 :WR (external data memory write strobe)
P3.7 :RD (external data memory read strobe)
Port 3 from
Pin-10 to Pin-17
IC 8051 Pin Description
External memory
reset
Add. Latch
enable
Program Store
Enable
crystal
IC 8051 Daily Applications
Digital clock
Moving message display
7 segment display
Traffic Light
IC 8051 Addressing Modes
•Immediate addressing modes
ADD A, #23h (Add immediate data to Acc)
•Register addressing modes
ADD A, R2 (Add register to Accumulator)
•Direct addressing modes
ADD A, 40h (Add data at location 40h to Accumulator)
•Register Indirect addressing modes
ADD A,@R2 (Add indirect RAM to Acc)
Interrupts in 8051
•
An interrupt is an external or internal event that interrupts the microcontroller to
inform it that a device needs its service
•
The advantage of interrupts is that the microcontroller can serve many devices
(not all at the same time)
Program
Program
Interrupt service
time
Interrupts in 8051
EA
-
ET2
ES
ET1
EX1
Internal Interrupts
EX0
ET0
EX1
ET1
ES
ET2
-EA
Enables or disables external interrupt
Enables or disables timer 0 overflow interrupt
Enables or disables external interrupt 1
Enables or disables timer 1 overflow interrupt
Enables or disables the serial port interrupt
Enables or disables timer 2 overflow or capture interrupt
Not implemented, reserved for future use
Disables all interrupts
External Interrupts
P3.2 :INT0 (external interrupt 0)
P3.3 :INT1 (external interrupt 1)
ET0
EX0
Seven Segment Display
7 pins of the microcontroller are used to shape the
character of your LED display
Port Relations Microcontroller with pin
7 Segment
Seven Segment Display
Table 1. Configuring the Character 7 Segment Data
8051
Microcontroller
Design Softwares
Software’s
Used
Keil µVision
Top View
Simulator
Express
PCB
Keil µVision IDE
 The µVision IDE from Keil
combines project management,
make facilities, source code
editing, program debugging, and
complete simulation in one
powerful environment. The
µVision development platform is
easy-to-use and helping you
quickly create embedded
programs that work. The µVision
editor and debugger are
integrated in a single application
that provides a seamless
embedded project development
environment.
Top View Simulator
• Topview Simulator gives an
excellent simulation environment
for MCS 51 Microcontroller.
A beginner can learn about 8051
based embedded solutions
without any hardware. An
experienced designer, you may
find most of the required facilities
built in the simulator that
enabling you to complete your
next project without waiting for
the target hardware.
Top View Simulator
A Top View
Simulator
Program
Express PCB
Express PCB allows you to design
schematics and PCB's. It is ideal
for those that are looking to
design anywhere from a two to
four layer circuit board.
A drop and drag design allows
users to pick the components of
the circuit board and drop it
onto the circuit board in the
software program. The designer
can then place various pins in the
circuit board to show where
things need to be connected.
It also has the ability of the
program to show the designer
where there are flaws in their
design.
Express PCB
This way we can include resistors
This way we can include different
kind of IC’s
DC Motor interfacing with
Microcontrollers
DC motors are always preffered over stepper motors.
There are many things which we can do with our DC motor when interfaced
with microcontroller.
For example:
we can control the speed of motor,
we can control the direction of rotation,
we can also do encoding of the rotation made by DC motor i.e. keeping track of
how many turns are made by our motors etc.
Usually H-bridge is preffered way of interfacing a DC motor.
L293D is most used H-Bridge driver IC.
LCD INTERFACE
Stepper Motor
Of all motors, step motor is the easiest to control. It's
handling simplicity is really hard to deny - all there
is to do is to bring the sequence of rectangle
impulses to one input of step controller and
direction information to another input. Direction
information is very simple and comes down to
"left" for logical one on that pin and "right" for
logical zero.
Motor control is also very simple - every impulse
makes the motor operating for one step and if
there is no impulse the motor won't start. Pause
between impulses can be shorter or longer and it
defines revolution rate. This rate cannot be infinite
because the motor won't be able to "catch up"
with all the impulses (documentation on specific
motor should contain such information)..
Interfacing of Stepper motor with
8051
MOTOR INTERFACING
Diagram of never falling robot
EDGE FOLLOWER ROBOTICS CKT
+12v
U1
9
13
12
40
39
38
37
36
35
34
33
1
2
3
4
5
6
7
8
RESET
XTAL1
XTAL2
PA0/ADC0
PA1/ADC1
PA2/ADC2
PA3/ADC3
PA4/ADC4
PA5/ADC5
PA6/ADC6
PA7/ADC7
PB0/T0/XCK
PB1/T1
PB2/AIN0/INT2
PB3/AIN1/OC0
PB4/SS
PB5/MOSI
PB6/MISO
PB7/SCK
ATMEGA16
PC0/SCL
PC1/SDA
PC2/TCK
PC3/TMS
PC4/TDO
PC5/TDI
PC6/TOSC1
PC7/TOSC2
PD0/RXD
PD1/TXD
PD2/INT0
PD3/INT1
PD4/OC1B
PD5/OC1A
PD6/ICP1
PD7/OC2
AREF
AVCC
22
23
24
25
26
27
28
29
14
15
16
17
18
19
20
21
32
30
16
2
7
1
9
10
15
IN1
IN2
EN1
EN2
IN3
IN4
VSS
GND
U2
8
VS
OUT1
OUT2
OUT3
GND OUT4
3
6
11
14
L293D
PROGRAM OF
NEVER FALLING
ROBOTICS
DDRA.0=1;
DDRA.1=1;
DDRA.2=1;
DDRA.3=1;
while (1)
{
PORTA.0=1;
PORTA.1=0;
OCR0=200;
PORTA.2=1;
PORTA.3=0;
OCR1A=200;
delay_ms(100);
PORTA.0=0;
PORTA.1=1;
OCR0=200;
PORTA.2=0;
PORTA.3=1;
OCR1A=200;
delay_ms(100);
PORTA.0=1;
PORTA.1=0;
OCR0=200;
PORTA.2=0;
PORTA.3=0;
OCR1A=200;
delay_ms(100);
PORTA.0=0;
PORTA.1=0;
OCR0=200;
PORTA.2=1;
PORTA.3=0;
OCR1A=200;
delay_ms(100);
}
}
APPLICATION OF 8051 MICROCONTROLLER
The 8051 has been in use in a wide number of devices, mainly because it is easy to
integrate into a project or build a device around. The following are the main
areas of focus:
i. Energy Management:Efficient metering systems help in controlling energy
usage in homes and industrial applications. These metering systems are made
capable by incorporating microcontrollers.
ii. Touch screens:A high number of microcontroller providers incorporate touchsensing capabilities in their designs. Portable electronics such as cell phones,
media players and gaming devices are examples of microcontroller-based touch
screens.
iii. Automobiles: The 8051 finds wide acceptance in providing automobile
solutions. They are widely used in hybrid vehicles to manage engine variants.
Additionally, functions such as cruise control and anti-brake system have been
made more efficient with the use of microcontrollers.
iv. Medical Devices:Portable medical devices such as blood pressure and
glucose monitors use microcontrollers will to display data, thus providing
higher reliability in providing medical results.