1, Analog/Digital Circuit Analysis and Design. Everything in the textbook is good, including signal amplification, filtering, waveform generation, regulated power supply, logic simplification, basic flip-flop, basic counter, register, pulse generation and shaping, ADC, DAC, phase-locked loop and so on. We should be able to analyze and design the function and performance of the circuit qualitatively and quantitatively, such as stability and frequency characteristics. These things generally need to accumulate over time to be well informed, and then practice makes perfect.
2. Computer principle and structure. At present, there are basically no electronic devices that do not use computers, so it is necessary to know computers, and it is best to be familiar with computers. Understand how the computer works, how the software works in the computer (it is best to write the program yourself), be familiar with the peripheral circuits and interfaces of common computer systems, and understand how the CPU and peripheral circuits work in harmony, etc. It is best to be familiar with MCS-5 1. Writing programs is not a problem. What matters is the idea, but you must do it.
3. PCB. The basic requirement is a four-layer board. We should understand the influence of PCB on EMI and ESD and find ways to avoid it. It takes time to train PCB beautifully and without problems.
4, VHDL language. This needs to master the basic skills abroad, and it is also popular in China. Mainly used for developing FPGA/CPLD devices and logic simulation, VHDL is often used as the input of ic design. For the time being, if you are not too demanding of yourself, you don't have to master it.
If time and energy permit, you can learn operating system, data structure and so on. Of course, you must master the C(C++) language first, so that you can work in the (software/hardware) system in the future. But the foundation of analog/digital electricity must be good, which is the basis of learning other things. At the beginning, we usually start with the analysis of the circuit to understand how the current flows in a circuit, how the voltage is generated, how the inductance and capacitance are discharged, and so on. From simple to complex, get into the habit slowly, and many things will be understood naturally.
Knowledge that electronic hardware engineers need to master.
Part I: Hardware knowledge
I. Digital signals
1, TTL and TTL signals with buffer.
2. RS232 and its definition
3, RS485/422 (balanced signal)
4, dry contact signal
Second, the analog signal video
1, unbalanced signal
2. Balanced signal
Third, the chip
1, packaging
2、 7407
3、 7404
4、 7400
5、74LS573
6、ULN2003
7、74LS244
8、74LS240
9、74LS245
10、74LS 138/238
1 1、CPLD(EPM7 128)
12、 1 16 1
13、max69 1
14、max485/75 176
15、mc 1489
16、mc 1488
17、ICL232/max232
18、89C5 1
Fourth, discrete devices.
1, packaging
2. Resistance: power consumption and capacitance.
3. Capacitance
1) monolithic capacitor
2) Ceramic capacitor
3) electrolytic capacitor
4. Inductance coefficient
5. Power conversion module
6. Terminal blocks
7.LED light-emitting tube
8, 8 characters (* * * Yang and * * * Yin)
9. Transistor 2N555 1
10, buzzer
Five, the minimum system of single chip microcomputer
1, single chip microcomputer
2, watchdog and power-on reset circuit
3. Crystal oscillators and ceramic capacitors
Six, serial interface chip
1、eeprom
2. Serial input/output interface chip
3, serial advertising, up to
4. serial LED driver, max7 129
Seven, power supply design
1, switching power supply: device selection
2, linear power supply:
1) transformer
2) Bridges
3) electrolytic capacitor
3. Power protection
1) bridge protection
2) Single diode protection
Eight. maintain
1, power supply
2, watchdog
Step 3 signal
Nine, design ideas
1, power supply: voltage and current
2. Interface: serial port, switch input and switch output.
3, switch signal output conditioning
1)TTL ―& gt； relay
2) TTL-> relay (reverse logic)
3) TTL-> solid state relay
4) TTL-> LED (8 words)
5) relay > relay
6) relay > solid state relay
4, switch signal input conditioning
1) dry contact->; optical coupler
2) TTL-> optical coupler
5. consider the processing power of CPU
6. Consider becoming a product:
1) circuit board shape: size, abnormity, connector, space volume.
2) Modular design of circuit board
3) Cost analysis
4) Equipment redundancy
Power consumption of 1. resistor
2. Capacitor withstand voltage, etc.
5) Chassis
6) Selection of power supply
7) Modular design
8) Cost accounting
1. How to calculate the cost of the circuit board?
2. How to reduce the cost? Choose low-cost equipment with satisfactory functions.
X. Thinking about problems
1. How to detect and indicate RS422 signal?
2. How to detect and indicate RS232 signals
3. Design a 4-bit 8-word display board.
1) power supply: DC 12.
2) Interface: RS232
3) 4 digits, 3 "and 8 words (connected together)
4) brightness detection
5) secondary dimming
4. Design a 33-bit1"8-character display board.
1) power supply: DC5V
2) Interface: RS232
3) 3 lines 1 1 8 words, divided into 4, 3 and 4 groups, with spaces between lines.
4) Minimum system of single chip microcomputer
5) decoding logic
6) Display drive and drive device
5. Design the interface board between PCL725 and MOXA C 168P.
1) power supply: DC5V
2) Interface: PCL725/MOXA 8 RS232.
1.PCL725, vertical DB37, hole
2.MOXA C 168P, bending DB62
3) Switch output signal conditioning: 6 solid-state relays and 8 relays, which can be controlled and driven by any signal. Interface: solid state relay 5.08 is vertical and relay 3.5438+0 is vertical.
4) Switch input conditioning: the dry contact is closed at 1 or 0, and the interface is vertical at 3.85438+0.
5) RS232 adjustment:
1.LED indication
2. The first four RS232 full signals, and the last four only need TX, RX and 0.
3. No photoelectric isolation is needed.
4. Interface form: DB9 (needle) is upright.
Part II: Software knowledge
I. Assembly language
Two. C5 1
This part can be learned from n kinds of development boards bought in the market. As for the first part, someone needs to take it.
Why do you want to master this knowledge?
In fact, an electronic engineer puts a bunch of devices together, injects ideas (programs), completes the functions that cannot be completed when these devices are separated, and makes a finished product. The higher the required skills, the more complex the functions, the lower the cost, and the greater the market demand for the corresponding things, the more successful it will be. This is the value of electronic engineers themselves. From cost to product sales, the difference between them is the pursuit of enterprises. As the boss of an enterprise, I am looking for such an application in the market; For electronic engineers, it is to complete the requirements or applications put forward by the boss in the shortest time according to certain conception principles (lowest cost, highest reliability, smallest circuit board, most powerful function, etc.). ). The shortest time is directly related to the proficiency, work efficiency and working hours of electronic engineers. This is the value of electronic engineers abstracting electronic products into a hardware model, which consists of the following parts:
1) input
2) Processing core
3) output
There are basically the following possibilities for input:
1) keyboard
2) Serial interface (RS232/485/can bus/Ethernet /USB)
3) Switch value (TTL, current loop, dry contact)
4) Analog quantity (4~20ma, 0~ 10ma, 0~5V (balanced and unbalanced signals))
The output basically includes the following contents:
1) serial interface (RS232/485/can bus/Ethernet /USB)
2) Switch value (TTL, current loop, dry contact, power drive)
3) Analog quantity (4~20ma, 0~ 10ma, 0~5V (balanced and unbalanced signals))
4) LED display: LED, eight characters.
5) liquid crystal display
6) Buzzer
The processing core mainly includes:
1) 8-bit single chip microcomputer, mainly 5 1 series.
2) 32-bit arm MCU, mainly including atmel and Samsung series.
Now it seems that 5 1 series single-chip microcomputer can only do some simple applications. To put it bluntly, this chip does a single thing. If you do too much, you might as well use arm. You can also add an operating system to arm. This program is reliable and easy to write. Recently, Samsung's arm has been sought after and the price is cheap. There is also an interface between Ethernet and USB, and the development system in Zhou Ligong is also very cheap. As a product of learning ARM, it should be the best. As an industrial control, netizens have different opinions and disputes. Our company adopts atmel ARM9 1 series to develop 1 outdoor products, which are used outdoors in Beijing without any ventilation and heating measures, and have been running well since May last year. There have been successful application cases.
But for beginners, it should start with 5 1. On the one hand, 5 1 is still an entry-level chip, so it is better to practice it as a beginner. We can go over the above concepts. Many special single-chip computers also add some I/O, A/D and D/A on the basis of 5 1 core. It also lays a foundation for learning more advanced single chip microcomputer and ARM in the future.
Besides, it is not necessary for any boss to put the development of ARM level in the hands of a novice who has never even learned 5 1 to do complex parallel expansion on 5 1, such as expanding I/O port and A/D, D/A, etc.
You can directly buy a single chip microcomputer with A/D and D/A; Or directly use ARM, which has many I/O ports. I/O interface and A/D, D/A and SPI interfaces can be used to expand LED display screens, such as MAX72 19 chips.
There are some examples of parallel expansion in some older books on the market, such as RAM, EPROM, A/D, D/A and so on. I don't think it's necessary to read it. I know these things have existed in history.
This knowledge is the basic element of all products. So you need to learn and then apply it concretely.