stc89c52单片机介绍(Introduction of STC89C52 SCM)
stc89c52单片机介绍(Introduction of STC89C52 SCM)
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STC89C52
SCM introduction:
A single chip computer is a complete computer system that is integrated into a single chip. Despite most of his features
Integrated on a small chip, but it has most of the components needed for a full computer:
CPU
,
Memory, internal and external bus system, most will have the core. At the same time, such as communication interfaces,
Timer, real-time clock and other peripheral equipment. And now the most powerful single chip microcomputer system can even sound, map
Images, networks, and complex input and output systems are integrated into a single chip.
Microcontrollers are also known as microcontrollers
Microcontroler
) because it was first used in industrial control
Realm. SCM by chip only
CPU
Special processors have evolved. The earliest design concept was through
Pass a lot of peripherals and
CPU
Integrated into a single chip to make the computer system smaller and easier to integrate
Into complex and demanding control equipment.
INTEL
The
Z80
It was the earliest thought
The processor that you want to design, and then, the development of the microcontroller and the special processor will go their separate ways.
Early SCM is
Eight
Or
Four
Bit. One of the most successful is...
INTEL
The
Eight thousand and thirty-one
Because Jane
It's reliable and has good performance. It has received a great
deal of praise. Thereafter
Eight thousand and thirty-one
Developed on the
MCS51
Serial list
Sheet machine system. The single-chip microcomputer system
based on this system is still widely used until now. With the
industrial control collar
The increase in domain requirements began to appear
Sixteen
Bit microcontroller, but because the cost performance is not ideal, has not been widely
Applications.
Ninety
After the 1980s, with the development of consumer electronic products, SCM technology has been greatly improved.
along with
INTEL i960
A series, especially later
ARM
A wide range of applications,
Thirty-two
Bit microcontroller
generation
Sixteen
Bit microcontroller high-end status, and into the mainstream market. Traditional
Eight
Bit MCU performance is also
Has been improved rapidly, compared with the processing capacity
Eighty
It has increased several hundred times in the 1980s. At present, high-end
Thirty-two
Bit monolithic
The main frequency of the machine has exceeded
300MHz
The performance catching.
Ninety
A dedicated processor in the mid-1990s, and a plain model
The factory price falls to
One
Dollars, the most high-end models are only
Ten
Dollar. Contemporary SCM system has not
Then only the bare metal environment in the development and use of special embedded operating system is widely used in the full range
Scm. In the palm computer and mobile phone core processing high-end microcontroller can even be used directly
Appropriative
Windows
and
Linux
Operating system.
SCM is more suitable for embedded systems than dedicated processors, so it has the most applications.
In fact, SCM is the largest number of computers in the world. Almost every piece of electronics used in modern human life
And mechanical products will be integrated with single-chip microcomputer. Mobile phones, telephones, calculators, home appliances, electronic toys,
Handheld computers and computer accessories such as the mouse are available
1-2
Mcu. And there are a few in the personal computer
Many SCM work. The car is usually equipped
Forty
Multiple single-chip microcomputer, complex industrial control system
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There may even be hundreds of microcontrollers working at the same time! The number of SCM is not only far exceeded
PC
Machines and other meters
The calculations are even more numerous than the number of human beings.
Single chip microcomputer is also called a single chip microcontroller
,
It is not a chip that performs some logical function
,
It's a plan
The computer system is integrated into a single chip. To sum up: a chip becomes a computer. Its volume
Small, light quality, cheap price, for learning, application and development provides convenient conditions. At the same time, learn to use
SCM is the best choice to understand the principles and structure of the computer.
SCM internal and computer functions similar modules, such as
CPU
Memory, parallel bus, etc.
A memory device that has the same function as a hard disk, and
differs from each other in terms of its performance relative to our home appliances
The brain is weak, but the price is low, usually not more than
Ten
Yuan can
......
Use it to make some control appliances
A class of work that is not very complicated is enough. We now use the automatic drum washing machine, smoke hood,
VCD
And so on inside the appliance, you can see its shadow! It is mainly used as the core part of the control part.
It is an on-line real-time control computer, on-line is field control, need is stronger
Anti-interference ability, low cost, and this is also with offline computers (such as home)
PC
Main area
Don't.
SCM is dependent on procedures, and can be modified. Realize different functions through different programs, especially
It's a special, unique feature, something else that needs a lot of effort to do, and some of them
It's hard to do it with great effort. A not very complex function, if used in the United States
Fifty
Developed in the 1990s
Seventy-four
Series, or
Sixty
Age
CD4000
The series of pure hardware to fix, the circuit must be a big
PCB
Board! But if you use the United States
Seventy
The success of the series of single-chip microcomputer in the market, the results will be
A world of difference~ Just because of the single chip
microcomputer, you can achieve high intelligence, high efficiency and high efficiency through the program you write
Reliability!
Because SCM is sensitive to cost, so the current dominant software is the lowest level assembly language
Language, it is in addition to the binary machine code above the lowest level language, since it is so low-level, why use?
? Many advanced languages have reached the level of visual programming, why not? The reason is simple,
SCM is not the same as the home computer
CPU
And there is no mass storage device like hard disks.
A visual high-level language applet, which even if only a button, it will reach dozens
K
The
Dimension! For home use
PC
The hard disk is nothing, but for the microcontroller is not acceptable.
single
Using the machine in terms of hardware resources to be very high for the rate, therefore assemblyalthoughprimitive actually make a lot
Use. The same reason, if the giant computer operating systems and applications to the home
PC
come up
Run, home
PC
You can't stand it.
It can be said that in twentieth Century, the "three electric" times, namely the electrical age, the electronic age, and now
Access to the computer age. However, this kind of computer usually refers to personal computers
PC
Machine. It comes from the Lord
Machine, keyboard, display and so on. There's another type of computer that most people don't know very well. This calculation
A machine is a single chip microcomputer (also called a microcontroller) that gives intelligence to a wide range of machines. As the name suggests, this kind of computer
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The minimal system can be easily operated and controlled with only one integrated circuit. Because it's small enough to pass through
Often hidden in the stomach of a charged machine. It plays the role of the human mind in the whole device,
Something went wrong and the whole device was paralyzed. Now, the use of this microcontroller has been very extensive, such as
Intelligent instrument, real time industrial control, communication equipment, navigation system, home appliance,
etc.. A variety of products once used
SCM can play the role of upgrading the product, often preceded by the product name as an adjective - "wisdom."
Can be type, such as intelligent washing machines, etc..
Now some factory technicians or other amateur electronic developers do it
Some products out of the circuit is not too complicated, that is, the function is too simple and very easy to be copied. Investigate its reason,
May be stuck on the product, not using a microcontroller or other programmable logic device.
STC89C52
It's a kind of band
8K
Byte blinking programmable erasable read only memory
(
FPEROM-Flash, Programable, and, Erasable, Read, Only, Memory
).
Low voltage, high performance
COMOS8
Microprocessor, commonly known as single chip microcomputer.
The device is adopted
ATMEL
Engage in secret
Manufacturing, manufacturing, and industrial standards of
nonvolatile memory
MCS-51
Instruction set and output pin phase
Volume.
SCM total control circuit as follows
Four
-
One
:
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chart
Tutu
chart
Four
-
-
-
One
SCM total control circuit
SCM total control circuit
SCM total control circuit
SCM total control circuit
One
Clock circuit
STC89C52
Internally, a high gain inverting amplifier is used to form the
oscillator pin
RXD
and
TXD
Input and output of the amplifier respectively. Clocks can be
produced internally or externally
Type production. The internal mode of the clock circuit is shown
in Fig.
Four
-
2 (a)
As shown in
RXD
and
TXD
The external pin
Timing element, the internal oscillator generates self-excited oscillation. The timing element is usually made of quartz crystals and capacitors
Parallel resonant circuit. Crystal oscillation frequency can be found in
One point two
~
12MHz
Between, the capacitor value in
Five
~
30pF
Between the capacitors, the size of the capacitor can play a role in trimming the frequency.
The external mode of the clock circuit is shown in Fig.
Four
-
Two
(
B
As shown,
RXD
Earthing,
TXD
External oscillator.
The external oscillation signal has no special requirement. Only the pulse width is guaranteed, and the frequency is lower than that of the external oscillation signal
12MHz
Square wave signal. The on-chip clock generator divides the oscillation frequency two to produce a two phase clock
P1
and
P2
,
For SCM use.
Show,
RXD
Earthing,
TXD
External oscillator. External oscillation signal has no special requirement, only request
Guaranteed pulse width is generally below the frequency
12MHz
Square wave signal. The on-chip clock generator oscillates
Frequency two divider generates a two phase clock
P1
and
P2
For SCM use.
RXD
Earthing,
TXD
External oscillator. There is no special requirement for external oscillation signal, only guarantee
Pulse width is generally lower than frequency
12MHz
Square wave signal. The internal clock generator oscillates the
oscillator frequency
Two frequency divider generates a two phase clock
P1
and
P2
For SCM use.
(
((
(
A
)
))
Internal mode clock circuit
Internal mode clock circuit
Internal mode clock circuit
Internal mode clock circuit
(
((
(
B
)
))
External mode clock circuit
External mode clock circuit
External mode clock circuit
External mode clock circuit
chart
Tutu
chart
Four
-
-
-
Two
Clock circuit
Clock circuit
Clock circuit
Clock circuit
Two
Reset and reset circuit
(
One
Reset operation
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Reset is the initialization operation of single chip microcomputer. Its main function is to bring
PC
Initialize to
0000H
Make single
Chip machine
0000H
The unit starts executing the program. In addition to the normal initialization of the system, due to
In order to get out of the difficulty, the system needs to press the reset button again when the system is in a deadlock state
Start up.
except
PC
Outside,
The reset operation also affects some other registers, and
their reset status is shown in Table 1
As shown.
surface
Table
Table 1
one by one
One
The reset status of some registers
The reset status of some registers
The reset status of some registers
The reset status of some registers
register
Reset state
register
Reset state
PC 0000H TCON 00H
ACC 00H TL0 00H
PSW 00H TH0 00H
SP 07H TL1 00H
DPTR 0000H TH1 00H
P0-P3 FFH SCON 00H
IP XX000000B SBUF
Indefinite
IE 0X000000B PCON 0XXX0000B
TMOD 00H
(
Two
Reset signal and its generation
RST
The pin is the input terminal of the reset signal. The reset
signal is active high, and the active time should be maintained
Continued
Twenty-four
Oscillating period
(
That is, two machine cycles
)
Above。 If the use rate is
6MHz
The crystal oscillator is reset
Signal duration shall exceed
4us
To complete the reset operation.
The logic of the circuit that produces the reset signal is shown
in Fig.
Four
-
Three
As shown:
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chart
Tutu
chart
Four
-
-
-
Three
Circuit logic diagram of reset signal
Circuit logic diagram of reset signal
Circuit logic diagram of reset signal
Circuit logic diagram of reset signal
The whole reset circuit includes two parts inside and outside the chip. A reset signal produced by an external circuit
(RST)
Send to
The Schmidt flip-flop is then replaced by an on-chip reset circuit in each machine cycle
S5P2
Time for Schmidt flip flops
The output is sampled before obtaining the signal needed for internal reset operation.
Reset operation on power, automatic reset button, manual reset two ways.
The power on auto reset is realized by charging the capacitor of the external reset circuit
Four
-
Four
(
A
As shown. Then, as long as the power
Vcc
The rise time does not exceed
1ms
It can be implemented automatically
Electrical reset, that is, through the power supply, it becomes a system reset initialization.
Manual reset button, level mode and pulse mode of two. Wherein, the key level reset is accomplished by resetting the key level
Bit by resistance and
Vcc
When the power is connected, the circuit is as follows
Four
-
Four
(
B
As shown; and the key pulse
Flush reduction is the use of
RC
A positive pulse produced by a differential circuit,
The circuit is shown in Fig.
Four
-
Four
(
C
As shown:
(
((
(
A
)
))
Power on reset
Power on reset
Power on reset
Power on reset
(
((
(
B
)
))
Button level reset
Button level reset
Button level reset
Button level reset
(
((
(
C
)
))
Button reset
Key pulse reset
Key pulse reset
Key pulse reset
chart
Tutu
chart
Four
-
-
-
Four
Reset circuit
Reset circuit
Reset circuit
Reset circuit
The resistor and capacitor parameters in the above circuit
diagram apply to
6MHz
Crystal oscillator, can guarantee the reset signal high
electricity
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Mean duration is greater than
Two
Machine cycle.
The reset circuit of the system adopts the diagram
Four
-
Four
(
B
Power on reset mode.
STC89C52
Details are as follows:
Main power pin
Two
Root)
VCC (Pin40)
Power input, +
5V
Power Supply
GND (Pin20)
Ground wire
External crystal pin (external pin)
Two
Root)
XTAL1 (Pin19)
The input of the on-chip oscillation circuit
XTAL2 (Pin20)
The output of an on-chip oscillation circuit
Control pin
Four
Root)
RST/VPP (Pin9)
: the reset pin appears on the pin
Two
The high level of the machine cycle will enable the microcontroller
Reset.
ALE/PROG (Pin30)
Address latch enable signal
PSEN (Pin29)
Read strobe signal for external memory
EA/VPP (Pin31)
The internal and external strobe of the program memory is connected to the low level and read from the external program memory
Instruction, if high, reads instructions from internal program memory.
Programmable input
/
Output pin
Thirty-two
Root)
STC89C52
SCM
Four
group
Eight
Bit programmable
I/O
Mouth position
P0
,
P1
,
P2
,
P3
Every mouth has a mouth
Eight
(a
Eight
Root pin) a total of
Thirty-two
Root.
PO
(export
Pin39
~
Pin32
):
Eight
Bit bidirectional
I/O
Mouth line, the name of
P0.0
~
P0.7
P1
(export
Pin1
~
Pin8
):
Eight
Quasi bidirectional
I/O
Mouth line, the name of
P1.0
~
P1.7
P2
(export
Pin21
~
Pin28
):
Eight
Quasi bidirectional
I/O
Mouth line, the name of
P2.0
~
P2.7
P3
(export
Pin10
~
Pin17
):
Eight
Quasi bidirectional
I/O
Mouth line, the name of
P3.0
~
P3.7
STC89C52
The main functions are shown in table two.
Table two
STC89C52
major function
Main functional characteristics
compatible
MCS51
Instruction set
8K
Repeatedlyrewritable
Flash ROM
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Thirty-two
Two way
I/O
mouth
256x8bit
inside
RAM
Three
individual
Sixteen
Bit programmable timing
/
Counter interrupt
clock frequency
0-24MHz
Two
Serial interrupt
Programmable
UART
Serial channel
Two
External interrupt source
common
Six
Middle fault source
Two
Read write interrupt line
Three
Level encryption bit
Low power idle and power down modes
The software sets sleep and wake up functions
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