Transcript Embedded System - 123seminarsonly.com

EEAST is a complete R & D Organization
dedicated to provide Electronics and
Advanced
Software Products and Solutions to its Clients.
Achieving the needs of our customer and converting
their ideas to real models is our motto.
We are working in the field of
Embedded Systems, Automation and Advanced
System design for the last four years with the
vision of becoming a center of Excellence to provide
Solutions, Services and Training in
various fields of technologies.
• Embedded system means the processor is embedded
into that application.
• An embedded product uses a microprocessor or
microcontroller to do one task only.
• In an embedded system, there is only one application
software that is typically burned into ROM.
• Example：printer, keyboard, video game player
• Things with computers that are not computers
themselves
– Refrigerators, toys, industrial robots, ...
• 98% of all microprocessors go into embedded
systems
– Embedded systems are everywhere!
– 50% much smaller than PC microprocessors
• 8-bit microprocessors
• Use a microprocessor or microcontroller to do
one task only
– Printer
• PC used for any number of applications
– Word processor, print-server, bank teller terminal,
video game player, network server, internet terminal
• PC contains or is connected to various embedded
products
– Keyboard, printer, modem, disk controller, sound card,
CD-ROM driver, mouse
• X86 PC embedded applications
• Home
– Appliances, intercom, telephones, security
systems, garage door openers, answering
machines, fax machines, home computers, TVs,
cable TV tuner, VCR, camcorder, remote controls,
video games, cellular phones, musical instruments,
sewing machines, lighting control, paging, camera,
pinball machines, toys, exercise equipment
• Office
– Telephones, computers, security systems, fax
machines, microwave, copier, laser printer, color
printer, paging
• Auto
– Trip computer, engine control, air bag, ABS,
instrumentation, security system, transmission
control, entertainment, climate control, cellular
phone, keyless entry
• The microprocessor is the core of computer
systems.
• Nowadays many communication, digital
entertainment, portable devices, are
controlled by them.
• A designer should know what types of
components he needs, ways to reduce
production costs and product reliable.
Introduction
General-purpose microprocessor
• CPU for Computers
• No RAM, ROM, I/O on CPU chip itself
• Example：Intel’s x86, Motorola’s 680x0
CPU
GeneralPurpose
Microprocessor
Many chips on mother’s board
Data Bus
RAM
ROM
I/O
Port
Address Bus
General-Purpose Microprocessor System
Timer
Serial
COM
Port
Microprocessor vs. Microcontroller
Microprocessor
• CPU is stand-alone, RAM,
ROM, I/O, timer are separate
• designer can decide on 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
• single-purpose
Microprocessor vs. Microcontroller
• Computing needs
– Speed, packaging, power consumption, RAM,
ROM, I/O pins, timers, upgrade to high
performance or low-power versions, cost
• Software development tools
– Assembler, debugger, C compiler, emulator,
technical support
• Availability & source
Microcontroller :
• A smaller computer
• On-chip RAM, ROM, I/O ports...
• Example：Motorola’s 6811, Intel’s 8051, Zilog’s Z8 and PIC 16X
CPU
I/O
Port
RAM
ROM
Serial
Timer COM
Port
A single chip
Microcontroller
Companies Producing
8051/8952
• Some Companies Producing a Member of
the 8051/8952 Family
Company
Web Site
Intel
www.intel.com/design/mcs51
Atmel
www.atmel.com
Philips/Signetics
www.semiconductors.philips.com
Siemens
www.sci.siemens.com
Dallas Semiconductor
www.dalsemi.com
Advantages of using MCU
•
•
•
•
•
Small – Single chip is smaller than a PC
Cheap
Low power consumption
Low heat
High efficiency – have only required
units
Three criteria in Choosing a Microcontroller
1.
meeting the computing needs of the task efficiently and
cost effectively
• speed, the amount of ROM and RAM, the number of
I/O ports and timers, size, packaging, power
consumption
• easy to upgrade
• cost per unit
2. availability of software development tools
• assemblers, debuggers, C compilers, emulator,
simulator, technical support
3. wide availability and reliable sources of the
microcontrollers.
Contents:
Introduction
Block Diagram and Pin Description of
the AT89C52.
Registers
Memory mapping in AT89C52.
AT89C52 Flag bits and the PSW
register
Stack in the AT89C52.
8051 Family
• Comparison of 8051 Family Members
Feature
8051
8052 8031
ROM (on chip 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
Inside 8051 Microcontroller
• Introduced by Intel in 1981
Pin Description of the 8051
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
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
8051
40
39
38
37
36
35
34
33
32
31
30
29
28
27
26
25
24
23
22
21
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)
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.
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
Pins of I/O Port
• The 8051 has four I/O ports
– 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）
– 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).
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.
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.
Dual Role of Port 0
• When connecting an 8051/8031 to an external memory, the 8051
uses ports to send addresses and read instructions.
– 8031 is capable of accessing 64K bytes of external memory.
– 16-bit address：P0 provides both address A0-A7, P2 provides
address A8-A15.
– Also, P0 provides data lines D0-D7.
• When P0 is used for address/data multiplexing, it is connected to the
74LS373 to latch the address.
– There is no need for external pull-up resistors
Port 0 with Pull-Up Resistors
Vcc
Port
DS5000
8751
8951
P0.0
P0.1
P0.2
P0.3
P0.4
P0.5
P0.6
P0.7
10 K
0
Registers
A
B
R0
R1
R2
PC
PC
R3
R4
R5
R6
R7
Some 8-bitt Registers of
the 8051
Some 8051 16-bit Register
8051 Flag bits and the PSW register
• PSW Register
CY
AC
F0
RS1
RS0
OV
--
Carry flag
Auxiliary carry flag
Available to the user for general purpose
Register Bank selector bit 1
Register Bank selector bit 0
Overflow flag
User define bit
Parity flag Set/Reset odd/even parity
RS1
RS0
Register Bank
P
PSW.7
PSW.6
PSW.5
PSW.4
PSW.3
PSW.2
PSW.1
PSW.0
CY
AC
-RS1
RS0
OV
-P
Address
0
0
0
00H-07H
0
1
1
08H-0FH
1
0
2
10H-17H
1
1
3
18H-1FH
Stack in the 8051
• The register used to access
the stack is called SP (stack
pointer) register.
7FH
Scratch pad RAM
30H
• The stack pointer in the
8051 is only 8 bits wide,
which means that it can take
value 00 to FFH. When
8051 powered up, the SP
register contains value 07.
2FH
Bit-Addressable RAM
20H
1FH
18H
17H
10H
0FH
08H
07H
00H
Register Bank 3
Register Bank 2
(Stack) Register Bank 1
Register Bank 0
Now we can
program...
● But how do we
get the programs
onto the devices?
WITH THE USE OF KEIL
SOFTWARE
• Write a program in embedded C language.
• Execute it.
• View the output of program on peripheral
devices as provided in Keil software.
• Now burn the program on AT89C52 using
burner.
• Now apply the chip with hardware.
Interfacing
• hardware or software used to interface two
computers or programs or devices
Interfacing used
•
•
•
•
•
•
LED
Seven Segment Display
LCD Display
Stepper Motor
Switch
Buzzer
AUTOMATIC CAR PARKING
• Block Diagram
• Layout
• Circuit Diagram
BLOCK DIAGRAM
STEPPER MOTOR
STEPPER MOTOR
• This animation demonstrates the principle for a stepper motor using full step
commutation. The rotor of a permanent magnet stepper motor consists of
permanent magnets and the stator has two pairs of windings. Just as the rotor
aligns with one of the stator poles, the second phase is energized. The two
phases alternate on and off and also reverse polarity. There are four steps. One
phase lags the other phase by one step. This is equivalent to one forth of an
electrical cycle or 90°.
STEPPER MOTOR
• This stepper motor is very simplified. The rotor of a real stepper motor usually
has many poles. The animation has only ten poles, however a real stepper
motor might have a hundred. These are formed using a single magnet mounted
inline with the rotor axis and two pole pieces with many teeth. The teeth are
staggered to produce many poles. The stator poles of a real stepper motor also
has many teeth. The teeth are arranged so that the two phases are still 90° out
of phase. This stepper motor uses permanent magnets. Some stepper motors
do not have magnets and instead use the basic principles of a switched
reluctance motor. The stator is similar but the rotor is composed of a iron
laminates.
STEPPER MOTOR
• Note how the phases are driven so
that the rotor takes half steps
STEPPER MOTOR
• Animation shows how coils are
energized for full steps
STEPPER MOTOR
• Full step sequence
showing how binary
numbers can control
the motor
• Half step
sequence of
binary
control
numbers
LCD Display
Optocoupler Devices
IC’s used in Automation ,to provide isolation
Why isolation is required?
Because microcontroller works on 5V and other
devices(Stepper Motor , Fan) works on greater
than 5V . Any spike of greater of 5V can burn
microcontroller .
Pin diagram of 4N35
Electromagnetic Relay