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MCU mind map

This is a mind map about microcontrollers, including STC microcontroller architecture, timers/counters, serial, etc. Interested friends are welcome to follow and collect!

Edited at 2023-11-06 11:51:40

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MCU mind map

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Outline

Microcontroller Principles and Applications

Basic knowledge of microcontrollers and embedded systems

Embedded

basic concept

Embedded systems are specific application-oriented, with computer technology as the core, and hardware and software based on specific applications. Portable microcomputer system tailor-made for software system

main feature

Small size and light weight

Low power consumption

lower cost

Rich application support

The composition of embedded technology

Embedded system hardware

embedded processor

It is the core of the embedded system and the hardware unit that controls and assists the operation of the system.

power supply system

Provide power to embedded systems

external memory system

Expand large-capacity memory through the external memory interface provided by the embedded processor

external device

Connect to external devices through the peripheral interface provided by the embedded processor chip

Embedded system software

Board support package

Embedded real-time operating system

app

Internal architecture of 8051 microcontroller

CPU

Exchange information with different types of storage in different address spaces

Execute logical and arithmetic instructions

program memory

Used to save program code to be executed

random access memory

Used to temporarily store data that needs to be saved temporarily in the program

interrupt system

Used for CPU processing of emergency events

Timer/Counter

Synchronize different events

External device interface module

Provides universal input/output

bus

A collection of related logical signals

STC microcontroller hardware knowledge

STC microcontroller IAP and ISP

ISP, that is, In-System Programming, a microcontroller chip with ISP function can directly write or erase programs to the chip on the circuit board through a simple download line, and supports online debugging.

IAP (In-Application Programming) means that the MCU can obtain new codes in the system and reprogram itself, that is, the program can be changed using the program.

Naming rules: ①, XXX ②, 15 ③, X ④X ⑤XX ⑥X- ⑦XX ⑧X ⑨-XXX ⑩X

1. Indicates STC, IAP or IRC

2. It means it is STC’s 15 series microcontroller.

3. Indicates the operating voltage of the microcontroller, represented by F, L, and W:

F means Flash, the working voltage is 3.8~5.5V

L means low voltage, the working voltage is 2.4~3.6V

W represents wide voltage, the operating voltage is 2.5~5.5V

4. Used to indicate the capacity of the SRAM storage space in the microcontroller.

5. Indicates the size of the program memory in the microcontroller

6. Indicates some special functions of the microcontroller

W: Indicates that there is a dedicated timer for power-down wake-up.

S: indicates there is a serial port

AS/PWM/AD: Indicates a set of high-speed asynchronous serial communication interface; SPI function; internal EEPROM function; A/D conversion function (PWM can also be used as a D/A converter); CCP/PWM/PCA function.

S4: Indicates that there are 4 sets of high-speed asynchronous serial communication interfaces; SPI function; internal EEPROM function; A/D conversion function (PWM can also be used as a D/A converter); CCP/PWM/PCA function.

7. Indicates the operating frequency of the microcontroller

8. Indicates the operating temperature range of the microcontroller.

C means commercial grade, its working temperature is 0~70℃.

Ⅰ indicates industrial grade, and its working temperature is -40~85℃.

9. Indicates the microcontroller package type

Dual in-line package, DIP

Thin square flat packaging, LQFP

Small Outline Package, SOP

Thin Shrink Small Outline Package, TSSOP

Square flat leadless package, QFN

10. Indicates the number of pins of the microcontroller

Pin definition

General I/O port, control/driver

Input: switch Output: motor

Data/address bus AD

External control POM, RAM

Serial communication

Receive RXDn

Send TXDn

External interrupt signal introduction port, INTN

Timing/counting counting pulse, pulse introduction T0, T1

I/O driving principle of STC microcontroller

Quasi-bidirectional output configuration

Can be used for output, input

Strong push-pull output configuration

Strong push-pull mode is generally used when larger drive current is required.

Configured for input only (high impedance)

This configuration cannot output or receive current, and can only be used as input data.

Open drain output configuration

STC microcontroller architecture

STC microcontroller CPU core functional unit

central processing unit

operator

8-bit arithmetic logic unit

arithmetic operations

Other operations

logic operation

Bitwise operations

accumulator

Used to save the results of most instruction operations, located in the special function register, address 0xE0

B register

Used for general purpose registers, located at the location of special function register 0xE0

program status word

Save some special bits

controller

Program CounterPC

Implement control and computing

sequential execution

non-sequential execution

command channel

fetch unit

Fetch instructions based on the address of the instruction program memory pointed to by the PC.

decoding unit

Translate the instruction based on the opcode part of the fetched instruction

execution unit

Control the arithmetic unit to complete the instruction

Stack and pointer

Mainly used to preserve the scene

CPU peripherals

Internal data RAM

external data space

Special function register SFR

Port mode control register

Provide P0 port, P1 group port, P2 group port, P3 group port, P4 group port, P5 group port, and P6 group port port, P7 group port

P0 port

P0M0 register P0M1 register

port register

STC microcontroller can read port status or write data to the port

clock divider

CPU dividers allow the CPU to run at different speeds

STC microcontroller memory structure and address space

Program Flash memory

Program memory space mapping

The STC microcontroller program storage space is located in the address range of 0x0000~0xFFFF

Program memory features

Provides more than 100,000 erasing and writing capabilities.

Low-voltage protection function, that is, erasing and programming of the program memory is prohibited under low-voltage conditions.

The program memory does not provide external read circuits, thus effectively preventing the cracking of user programs.

The program memory cannot be programmed until it has been erased.

When programming the program memory, the program code can be stored out of order.

The last 7 bytes of program memory set the globally unique ID number.

Erase in units of sectors.

Programming is done in bytes.

STC microcontroller provides the ability to erase, program and code encryption of Flash through a universal asynchronous serial port.

Data Flash memory

For implementing electrically erasable read-only memory

Features

The internal data Flash can be used as EEPROM through ISP/IAP technology.

The number of erases and writes is more than 100,000 times.

Measured in sectors, each sector contains 512 bytes.

Data memory erase operations are performed on a sector-by-sector basis.

Internal RAM memory

Internal RAM

0x00H~0xFFH

Internal RAM

0x0000~0x0EFF

interrupt system

Interrupt type

External interrupt 0

Timer/Counter T0

External interrupt 1

Timer/Counter T1

serial port interrupt

IE (interrupt type)

Main switch EA

EX0, ET0, EX1, ET1, ES, EA

TOCN (interrupt flag bit and interrupt mode)

IT0, IE0, IT1, IE1, TR0, TF0, TR0, TR1, TF1

IT is the trigger mode, 0 is low level, 1 is falling edge

TF is the timer overflow flag bit

IP (priority level)

natural order

External 0>Define 0>External 1>Define 1>Serial port

P.S.

Serial port interrupt priority control bit

PT1

Timer 1 interrupt priority

PX1

External interrupt 1 interrupt priority

PT0

PX0

interrupt process

interrupt request

interrupt response

interrupt service

interrupt return

Timer/Counter

Structure and working principle

substance

The falling edge of the accumulated pulse, after reaching a certain number, overflows and interrupts

Classification

timer

The pulse comes from the internal crystal oscillator

counter

The pulse comes from outside

several concepts

Counter capacity

The measurement range is expressed in binary digits, and the eight digits are 2 to the 8th power 256

Counter overflow

After reaching the measurement range, another pulse will return to 0.

overflow mark

Similar to the carry flag, the overflow flag causes an interrupt

Count initial value

16 bits, 65535, to count 100, set the initial value to 65436

control

Mode control register (TMOD)

The byte address is 89H

GATE

Gate control bit

Set to 0 to start Tx and has nothing to do with external interrupts

C/T(-)

Counting, timing function selection bit

Set 1 to count

Set 0 for timing

Working mode definition bit

Four ways of working

00 mode 0

13 bits

01 Method 1

16 bit

10 Method 2

8-bit auto-reload

11 Method 3

T0 is divided into two independent eight bits, and T1 is discontinued.

The lower four bits are timer 0, the higher four bits are timer 1

It cannot be bit addressed and can only be set using byte instructions.

Control register (TCON)

The byte address is 88H

TF1

The T1 timer overflow interrupt flag is set by hardware when it overflows, interrupt response, and automatically cleared.

TR1

Run control bit, when set to 1, starts corresponding T0/T1, set by software

TF0

The T0 timer overflow interrupt flag is set by hardware when it overflows, interrupt response, and automatically cleared.

TR0

Run control bit, when set to 1, starts the corresponding T0/T1, set by software

IE1

IT1

IE0

IT0

Way of working

Mode 0

13 bits

Way 1

THx and TLx form a 16-bit adding counter

The maximum count pulse is 65536

When GATE is set to 1, the switch of the counter is related to the external interrupt.

Way 2

16 bit

TLx eight bits to count

Eight bits of THx to store the initial value

After counting once, H will be imported once.

Way 3

Counter and pulse frequency

The highest external frequency is 1/24 of the oscillation period

Crystal oscillator 12MHz→250kHz

serial

Data transmission between microcontrollers and microcontrollers, microcontrollers and other devices

Parallel, serial

Parallel is slower than serial, and parallel can only be used at short distances

Serial communication method

Asynchronous communication

Data is transmitted frame by frame

Synchronous communication

Stop bits are not used, strict synchronization is required, and it is relatively rarely used.

Serial communication port control

Serial control register SCON

SM0/FE

SM1

Determine the communication method together with SM0

SM2

Allow mode 2 and mode 3 multi-machine communication control bit

REN

Enable or disable serial reception control bit

TB8

Data check bit or flag bit indicating address frame/data frame in multi-machine communication (this bit is not used in mode 0 and mode 1)

RB8

Parity data check bit or flag bit of address frame/data frame (this bit is not used in mode 0 and mode 1)

Send interrupt flag bit

Receive interrupt flag bit

Power control register PCON

SMOD

SMOD0

LVDF

POF

GF1

GF0

IDL

A microcontroller that supports IAP mode must also support ISP mode.