Do you know all the necessary hardware devices for self-learning microcontrollers?

Microcontrollers (Microcontrollers) are integrated circuit chips that use a VLSI technology to provide central processing unit (CPU) with data processing capabilities, random access memory (RAM), read-only memory (ROM), various I/O ports and interrupt systems, and timers. Functions such as counters/counters (which may also include display driver circuits, pulse width modulation circuits, analog multiplexers, A/D converters, etc.) are integrated into a single chip to form a small and complete microcomputer system in the industry. Wide application in the field of control. From the 80s of the last century, from the then 4-digit, 8-bit microcontroller, to the current 300M high-speed microcontroller.

First, basic

1. Learn "Circuit Theory", mainly to understand the basic element characteristics, the concept of voltage and current, the basic principles and laws of the circuit.

2, learning "analog electronic technology", focusing on learning diodes, transistors, amplifier circuits, integrated operational amplifier circuit, feedback, power circuit. The most important task: transistor, operational amplifier

3, learning "digital circuit", focus: D flip-flop, combinational logic gate circuit, simple sequential logic circuit.

Second, intermediate

4, learning MCS-51 microcontroller principles and interfaces, learning 51 assembly language, and C51 language, the compilation is more difficult, the realization of learning is not good, into the door on the line, as long as you can read on the line, now mainly with C language to develop SCM, It's best to buy a lab board. There are usually matching experiments that you can do while you are learning. 51 MCU focus: interrupts, timers, serial communications. When learning the SCM, you can first look at my "want to say something to the beginners of the SCM". According to what I said, it may speed up your SCM learning progress. Learned 51, you can look at PIC/AVR/msp430 and so on.

5, learning CPLD, HDL language: AHDL, or Verilog HDL, or VHDL, a simple combination of logic circuits and sequential circuits.

6, learning "signals and systems", "Communication Principles", focus on understanding the concept of time domain and frequency domain.

7. Learn “Sensor” to understand the use of sensors such as temperature and humidity

8, learning protel, will draw schematics and PCB

Third, senior

9, learning "digital signal processing", focus: FT transform, spectrum analysis, filter design

10, learning "digital image processing", focus: image conversion algorithm, codec, compression, etc.

11, learn DSP, ARM and FPGA, improve C language, Verilog HDL or VHDL design ability, realize the technology mentioned in 9,10.

12. Learn RTOS, TCP/IP, CAN, USB, FS, Linux

13, further study of PCB layout, it is best to learn PADS

In addition to computers, the following microcontrollers are needed to learn the MCU.

1, the experimental board

If you know nothing about the MCU, then it is a good choice to build or purchase an experiment board. Usually on the experimental board will be designed some switches, LED indicators, digital tubes, various interface chips and other commonly used devices, through the programming practice of these devices, and gradually master the microcontroller programming technology.

2, simulator

The purpose of the simulator is to replace the SCM chip on the circuit board. The simulator communicates with the PC through the serial port, USB interface, etc., and receives commands issued by the PC control software to run at single step, single step and full speed. When the program is executed in various ways such as single-step or single-step execution of the process, the execution result can be fed back to the PC-side control software after each execution of the program. Because the microcontroller must be clear about what kind of result each instruction will have after execution, make sure whether the actual result is consistent with the expected result. Therefore, the simulation function can play an important role in the learning and development of the microcontroller. Help function.

3, programmer or download line

Its purpose is to write code into the microcontroller chip. For learners, with the simulator can also be temporarily equipped with programmer or download line, because with the experimental board, the simulator can do experiments. However, it is recommended to configure one so that you can understand all aspects of microcontroller development.

4, multimeter, electric iron and other electronic production tools

The development of single-chip microcomputer is not a simple programming. Up to now, there are few pure "MCU programmers", and developers are usually required to be familiar with software and hardware. Therefore, these electronic productions still need to be equipped.

It should be noted that the simulation machines, experiment boards, download lines, or programmers mentioned here are all based on general concepts and do not involve specific products. There are also some products on the market that will be used to design the experiment board, Some or all of the simulation functions, downloads, or programming functions are integrated on one board to form a complete set of experimental systems.

1. Select the typical circuit as much as possible, and meet the general usage of the SCM. It lays a good foundation for the standardization and modularization of hardware systems.

2. The level of system expansion and configuration of peripheral devices should fully meet the functional requirements of the application system and leave room for further development.

3, the hardware structure should be considered together with the application software program. The hardware structure and the software solution will have mutual influence. The principle that is considered is: The functions that the software can achieve are implemented by software as much as possible to simplify the hardware structure. However, it must be noted that the hardware functions implemented by software generally have a longer response time than the hardware implementation and occupy CPU time.

4. The relevant devices in the system must match performance as much as possible. If CMOS chip microcontrollers are used to constitute a low-power system, all chips in the system should be selected as low-power products as possible.

5, reliability and anti-jamming design is an essential part of the hardware design, which includes the chip, device selection, decoupling filter, printed circuit board wiring, channel isolation and so on.

6, when the external circuit of the one-chip computer is more, must consider its driving ability. When the drive capability is insufficient, the system operation is not reliable, and the bus load can be reduced by adding a line driver to enhance the drive capability or reduce the chip power consumption.

7, as far as possible toward the "single" direction of the design of the hardware system. The more system devices, the stronger the mutual interference between the devices, and the power consumption, which inevitably reduces the stability of the system. With the increasing integration of single-chip microcomputer functions, the real system-on-chip SoC can already be realized. For example, the recently introduced μPSD32×× series of ST products integrates 80C32 core, large-capacity FLASH memory, SRAM, and A on a single chip. /D, I/O, two serial ports, watchdog, power-on reset circuit, etc.

First, the power is determined

The role of the power supply in the embedded system can be seen as the effect of air on the human body, and even more important: the air that humans breathe is oxygen, carbon dioxide, and nitrogen, but the content is stable, which is equivalent to all kinds of clutter in the power system. We hope to obtain pure and stable power supplies that meet the requirements, but due to various factors, it is only our dream.

Second, the crystal is determined

Crystal oscillator is equivalent to the heart of an embedded system. Its stability is directly related to its operating state and communication performance. The common vibration has the passive crystal oscillator, the active crystal oscillator, first must determine its oscillation frequency, second must determine the crystal oscillator type.

Third, reserve test IO port

In the embedded debugging stage, in the case of rich pin resources, I usually reserve an IO port to connect the LED or the speaker, which will pave the way for the next software development. The IO interface is properly controlled during the operation of the embedded system to determine whether the system is operating normally.

Fourth, external storage devices

If an embedded system has a power supply, a crystal, and a CPU, then this is the smallest system we are familiar with. If the embedded system needs to run a large operating system, not only does the CPU need to have an MMU, the CPU also needs an external SDRAM and NAND FLASH. If the CPU has SDRAM and NAND FLASH controllers, there is no need to consider the use of address lines in hardware design. If there is no relevant controller, then you need to pay attention to the use of the address line.

This part is a key point in LAYOUT. The reason is to make the relevant signal lines equal in length to ensure that the signal delay is equal, and the clock and the DQS differential signal lines are routed. In the wiring, various wiring techniques need to be comprehensively used. For example, symmetrical distribution with cpu, daisy-chain wiring, and T-type wiring, these need to be selected according to the number of memory. Generally, the more the number, the more complicated the wiring. , But knowing its key points, everything is solved.

Fifth, functional interface

The most important aspect of an embedded system is to control peripheral modules through various interfaces to achieve the designer's intended purpose. Commonly used interfaces are serial ports (which can be used to connect Bluetooth, wifi and 3G modules), USB interfaces, network interfaces, JTAG interfaces, audio and video interfaces, HDMI interfaces, and so on. Because these interfaces are connected with external modules, it is an important task to make electromagnetic compatibility design. In addition, pay attention to the use of differential lines at LAYOUT.

Sixth, screen

This function is listed separately because it is optional. If an embedded system is only connected to a peripheral module as a connector, connected to a host computer through an associated interface, or directly attached to the network, the screen is not needed. However, if you are making a consumer product and interacting with users frequently, you have to make a few words.

Capacitive screens are the first choice for embedded screens. Attention must be paid to the layout of touch screen connection lines and display screen connection lines in circuit design. In the process of routing as close as possible to the main control CPU, at the same time pay attention to pairing signal to take the differential line, RGB control signal to go equal length. The spacing of various signal traces follows the 3W rule to avoid mutual interference. In the design of the screen, it is necessary to ensure power and prevent interference in order to prevent the appearance of screen splashing and flowering.

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