当前位置:网站首页>Read the meaning of serial port and various level signals
Read the meaning of serial port and various level signals
2022-04-23 15:52:00 【ZONG_ XP】
0 background
Students who do embedded development or hardware development , You must hear it often RS232、RS485、TTL And so on , If you are not clear about these concepts , There will be problems in use , This paper introduces the meaning of these concepts ( See if the picture below is dizzy )
1 A serial port
First of all, make it clear , A serial port 、COM Port refers to the form of hardware interface , and TTL、RS-232、RS-485 Refers to the level signal
1.1 UART Interface
Universal asynchronous transceiver (UniversalAsynchronous Receiver/Transmitter),UART It is the logic circuit of serial port transceiver , This part can be made into a chip , It can also be embedded into other chips as a module , Single chip microcomputer 、SOC、PC There's going to be UART modular .
UART Yes 4 individual pin(VCC、GND、RX、TX), It's using TTL level , The low level is 0(0V), The high level is 1(3.3V Or more ).
1.2 COM mouth
COM Port is the serial communication port , Serial port for short , It's very common D type 9 Pin plug , There are only two protocols for this interface :RS-232 and RS-485. Will not be TTL Level . Generally, only RXD、TXD, Plus GND.
1.3 USB mouth
Universal serial bus , And serial port are two concepts . Although it's also serial communication , But because of USB The communication timing and signal level are completely different from serial port , So it has nothing to do with the serial port .USB It's a high-speed communication interface , be used for PC Connect all kinds of peripherals ,U disc 、 Key mouse 、 mobile hard disk drive 、 And of course "USB To serial port " Module .(USB Serial port module , Namely USB Interface UART modular )
2 TTL
TTL level : full duplex ( Logic 1:2.4V ~ 5V, Logic 0:0V ~ 0.5V)
How to connect
Level indication
3 RS232
It is the asynchronous transmission standard interface formulated by the electronics industry association , At the same time corresponding to the level standard and communication protocol ( sequential ), Its level standard :+3V ~ +15V Corresponding 0,-3V ~ -15V Corresponding 1.RS232 The logic level and TTL Not the same, but the agreement is the same .RS-232 Suitable for communication between local devices , The transmission distance generally does not exceed 20m.RS-232 Only one to one communication is allowed .
RS-232 level : full duplex ( Logic 1:-15V ~ -3V, Logic 0:+3V ~ +15V)
Connection diagram
Level indication
4 RS485
RS485 Is a serial interface standard , For long distance transmission, differential transmission is adopted , It's a differential signal , The anti-jamming ability is better than RS232 Much better . The pressure difference between the two lines is -(2~6)V Express 0, The pressure difference between the two lines is +(2~6)V Express 1.RS-485 The transmission distance is tens of meters to thousands of meters .RS-485 The interface on the bus is allowed to connect up to 128 A transceiver .
RS-485: Half duplex 、( Logic 1:+2V ~ +6V, Logic 0:-6V ~ -2V) The level here refers to AB The voltage difference between the two wires .
Connection diagram
Level indication
5 Conversion chip
5.1 USB turn TTL
PL2303、CP2102 The chip is USB turn TTL Serial port chip , use USB To expand the serial port (TTL level ).USB turn TTL The serial port is shown in the figure below :
5.2 TTL And RS-232 Interturn
MAX232 The chip is TTL Level vs RS232 Special bidirectional conversion chip for level , Sure TTL turn RS-232, It's fine too RS-232 turn TTL. Here's the picture :
Reference resources
A serial port 、TTL、232、485 difference _IOT-SYM The blog of -CSDN Blog _232 485 difference
A serial port 、COM mouth 、UART mouth , TTL、RS-232、RS-485 Detailed explanation _ level
版权声明
本文为[ZONG_ XP]所创,转载请带上原文链接,感谢
https://yzsam.com/2022/04/202204231547449004.html
边栏推荐
- Single architecture system re architecture
- Modèle de Cluster MySQL et scénario d'application
- Interview questions of a blue team of Beijing Information Protection Network
- Import address table analysis (calculated according to the library file name: number of imported functions, function serial number and function name)
- IronPDF for . NET 2022.4.5455
- Config learning notes component
- [self entertainment] construction notes week 2
- Extract non duplicate integers
- Load Balancer
- Implement default page
猜你喜欢
随机推荐
The principle and common methods of multithreading and the difference between thread and runnable
多生成树MSTP的配置
【第5节 if和for】
Configuration of multi spanning tree MSTP
Import address table analysis (calculated according to the library file name: number of imported functions, function serial number and function name)
Metalife established a strategic partnership with ESTV and appointed its CEO Eric Yoon as a consultant
5分钟,把你的Excel变成在线数据库,神奇的魔方网表excel数据库
JS regular détermine si le nom de domaine ou le chemin de port IP est correct
c语言---字符串+内存函数
Go language slice, range, set
Pytorch中named_parameters、named_children、named_modules函数
IronPDF for . NET 2022.4.5455
Go language, condition, loop, function
Redis master-slave replication process
Neodynamic Barcode Professional for WPF V11.0
MySQL集群模式与应用场景
Go语言条件,循环,函数
一刷312-简单重复set-剑指 Offer 03. 数组中重复的数字(e)
How do you think the fund is REITs? Is it safe to buy the fund through the bank
幂等性的处理