embedded system

1. Submitted By :-
Piyush Kansal
1320911
ECE

2. “Special purpose system which are either used as standalone or part of a
big system”
An Embedded System is one that has computer hardware with software
embedded in it as one of its important components.
An embedded product uses a microprocessor (or microcontroller) to do
one task and one task only.
A printer is an example of embedded system since the processor inside
it
performs only one task; namely, getting the data and printing it

3. Household appliances
Integrated systems in aircrafts
and missiles
Cellular telephones
Electric and Electronic Motor
controllers
Engine controllers in
automobiles
Calculators
Medical equipment’s
Videogames
Digital musical instruments
WHERE ARE THEY PRESENT
?

4.  CPU: Central Processing Unit
 I/O: Input /Output
 Bus: Address bus & Data bus
 Memory: RAM & ROM
 Timer
 Interrupt

5. “A Microprocessor is a general purpose chip used to create multifunction
device ”
No RAM, ROM, I/O ports on CPU chip itself
CPU is stand-alone, Must add RAM, ROM, I/O ports, and timers
externally to make them functional
Designer can decide on the amount of ROM, RAM and I/O ports
Example ： Intel’s x86, Motorola’s 680x0

6. “A Microcontroller is a computer-on-a-chip optimized to control Electronic
devices”
CPU + I/O + Timer(s) [+ ROM] [+ RAM] All on single chip
Limited RAM space, ROM space and I/O pins
Low chip-count to implement a small system
Low-cost at large quantities
Development tools readily available at reasonable cost

8. Microprocessor
 CPU is stand-alone, RAM, ROM, I/O, timer
are separate
• Designer can decide the amount of ROM,
RAM and I/O ports
• Expansive
 Versatility
• General-purpose
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
 Not Expansive
 Single-purpose

9. Following must be kept in mind while choosing a
microcontroller
 Speed
 Packaging
 Power consumption
 The amount of RAM and ROM on chip
 The number of I/O pins and the timer on chip
 How easy to upgrade to higher performance or lower power-
consumption versions
 Cost per unit

10. CPU
Program
+ Data
Address Bus
Data Bus
Memory
Von Neumann
Architecture
CPU
Program
Address Bus
Data Bus
Harvard
Architecture
Memory
Data
Address Bus
Fetch Bus
0
0
0
2n

11. The Intel 8051 is used in embedded systems
has
8-bit CPU
4k bytes ROM for the program
128 BYTES of RAM for variables
32 I/O lines ( 4 PORTS WITH 8 EACH )
2 timers
6 interrupt sources
Low cost per chip

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

13. 8051 microcontroller has four I/O ports P0, P1, P2 and P3 each use 8 pins making
them 8 bit ports. All the ports can be used as either input or output
Port 0: Port 0 occupies a total of 8 pins (pins 32-39) .It can be used for input or
output. To use the pins of port 0 as both input and output ports, each pin must be
connected externally to a 10K ohm pull-up resistor.
Port 1: Port 1 occupies a total of 8 pins (pins 1-8). It can be used as input or
output. In contrast to port 0, this port does not need any pull-up resistors since it
already has pull-up resistors internally.
Port 2 : Port 2 occupies a total of 8 pins (pins 21- 28). It can be used as input or
output. Just like P1, P2 does not need any pull-up resistors since it already has
pull-up resistors internally.
Port 3 : Port 3 occupies a total of 8 pins (pins 10 -17). It can be used as input or
output. P3 does not need any pull-up resistors, the same as P1 and P2 did not.
Port 3 has the additional function of providing some extremely important signals
such as interrupts, etc.

14. VCC (Pin-40): Vcc provides supply voltage to the chip. The
voltage source is +5V.
GND (Pin-20): It is ground pin.
RST (Pin-9): It is reset pin. Upon applying high pulse to this
pin the micro controller will reset and terminate all activities.
XTAL1 & XTAL2 (Pin-18,19): These 2 pins provide external
clock using a quartz crystal oscillator Crystal inputs for
internal oscillator.
PSEN (Pin-29): Program Store Enable, the read signal for
external program memory.

15. ALE (Pin-30): Address Latch Enable, to latch address outputs
at Port0 and Port2, used for both data and address transmission.
EA (Pin-31): External Access pin should be connected to Vcc in
order to fetch code from internal program memory and to fetch
code from external program memory EA is connected to Ground.
Interrupts (Pin-12,13): An interrupt is an event that disturbs the
microcontroller to inform it that a device needs its service.
Timers/Counters (Pin-14,15): They are used for counting
internal or external events.

16. TI MER 8051 is of two types
 Timer T0 16-bit
 Timer T1 16-bit
Features
 Both Timer T0 and T1 are 16 bits wide.
 When used as a “timer” the register is programmed
to count internal clock pulses
 When used as a “counter” the register is
programmed to count external clock pulses

17. Interrupt is an event that causes program to change
its normal execution and branch up to specific
subroutine putting normal program on hold.
Whenever any device needs its service, the device
notifies the microcontroller by sending it an interrupt
signal.
Upon receiving an interrupt signal, the microcontroller
interrupts whatever it is doing and serves the device.

18. Different addressing modes in 8051 microcontroller are
•IMMEDIATE ADDRESSING
•REGISTER ADDRESSING
•DIRECT ADDRESSING
•REGISTER INDIRECT ADDRESSING

19. Immediate Addressing :
This addressing mode is named as “immediate” because it transfers an data
immediately to the destination operand.
For example -
MOV A, #77H ; Loads 77 (hexadecimal) to A and stores in A
ADD A, #4DH ; Adds 4D (hexadecimal) to A and stores in A
MOV DPTR, #1234H ; Moves 1234 (hexadecimal) to data pointer
The ‘#’ symbol before 77H indicates that operand is a data (8 bit). If ‘#’ is not present
then the hexadecimal number would be taken as address
Register Addressing :
Used while moving data between two registers.
Moving data between two Rn registers is not allowed.
For example-
ADD A, R0 ;Adds content of R0 to A and stores in A
MOV A, R1 ;Copy contents of R1 into A

20. Direct Addressing :
There are 128 bytes of RAM in 8051 and have been assigned addresses 00
to 7FH. Entire 128 bytes of RAM can be accessed by using direct addressing
mode.
For example -
MOV R0, 088H; Save the contents of RAM location 88h to R0
Register Indirect Addressing :
An address is considered to be the address of an address, rather than the
address of a value.
For example -
MOV A, @R0; Moves content of address pointed by R0 to A
Value inside R0 is considered as an address, which holds the data to be
transferred to Accumulator.

21. Embedded systems are more than part of human life. For instance, one cannot imagine life without
mobile phones for personal communication. Its presence is virtually unavoidable in almost all facets of
human endeavor.
We can clearly identify the trend as to where the future of embedded systems is heading.
Conventionally, chip manufacturers developed faster single core processors to meet the ever increasing
performance requirements but soon they realized that increasing frequency, though offered certain
benefits had drawbacks too such as:
• It drove to higher power consumption
• Overall cost increased as the peripherals surrounding also needed to operate at matching
speed, which was truly not practical in all cases, there by driving the costs.
So semiconductor manufacturers recognized that the way forward is to build processors that run at
lower frequency and voltages but include parallel cores onto single chip. The overall performance
increases because multicores can perform more than one task at given point of time, so today most of
our devices such as smartphones, are indeed getting 'smarter‘ and ‘smaller’

22. Embedded operating systems
Traditionally embedded systems did away with an operating system (OS), it had lightweight
control program/monitor to offer limited I/O and memory services, however, as the systems
became complex, it was inevitable to have OS which offered low latency real-time response.
Most of the new designs today are moving away from proprietary OS and tool chains and are
more and more opting for open source platforms both of development and deployment as the
key market differentiator for them is cost.
Royalty free licensing deployment is the key for reducing the end user costs so OS like Linux
embedded and new OS such as Android are making inroads into places where traditionally
Windows CE/Vx works etc., used to play. Today many new handhelds and smart phones are
embracing Android.
Convergence embedded systems and applications
The retail segment is one of the fastest growing segments in emerging markets and the trend in
retail markets is moving towards improving the user experience, which is most certainly setting
trend towards increased performance, connectivity and rich graphics, while reducing power
consumption and size of the device.
Ultrabook is a latest example which aims in reducing size of conventional laptops, while
efficiently managing power consumption and also improving performance

23. Healthcare
Electronic medical devices and other technological innovations with the convergence of biotech,
nanotech, manufacturing tech making breathtaking transformations in healthcare delivery and
creating new health care paradigms.
The fastest growing markets within medical for semiconductors are home monitoring and
diagnostic device ECG, pulse rate, temperature, oxygen, blood pressure etc.
Embedded digital security and surveillance
In the ever increasing interconnected world, Digital embedded security is no more an option but
a necessity as it is very critical for more transactions happening over embedded devices as front
ends.
Digital security and surveillance is currently in the host of new applications in the embedded
arena which is benefiting from multicore phenomenon.
The applications based on computer vision and tracking offers multiple benefits in capturing, post
processing and identification and alerting of security video in real time.
Telecommunications
If ever there is an industry that has reaped the benefits to Embedded Technology, for sure, it is
only Telecommunications. The Telecom industry utilizes numerous embedded systems from
telephone switches for the network to mobile phones at the end-user.

24. Automotive
With drive across the world to improve on emission controls and bring in efficiency in
usage of fossil fuels, the automotive segment is challenged by various factors and
embedded systems are clearly the ways and means of achieving multiple objectives in
this segment taking it from infotainment systems, engine control unit, Car-area-network,
fuel management, safety systems all need embedded to be in it.
Entertainment
While we have seen mobiles, handhelds, iPods etc., have changed the landscape of the
personal entertainment in the world in the recent past, the emerging trend is adding more
intelligence in the personal entertainment, communication devices by converging the
social networks, city information, location based services into a single device.
Smart cards industry
Smart cards, though began prominently as either a debit or a credit card, are now being
introduced in personal identification and entitlement schemes at regional, national, and
international levels. Smart cards are appearing now as Citizen Cards, drivers’ licenses,
and patient cards.