当前位置:网站首页>Easy to understand IIC protocol explanation
Easy to understand IIC protocol explanation
2022-07-06 05:23:00 【Embedded base】
I2C The bus is a simple 、 Two way two wire synchronous serial bus .
I2C The communication protocol has few pins , The hardware implementation is simple , High scalability , Unwanted USART、CAN And other communication protocols , It is widely used in multiple integrated circuits in the system (IC) Communication between .
I2C Information exchange is completed by two signal lines ,SCL It's a clock signal line ,SDA For data entry / Output line .
I2C Support multiple slaves (Slaver), It can also support multi host mode (Master). Most of the I2C Device support 100kHz and 400kHz Pattern , Some special applications can also be designed to support 3.4MHz.
I2C Its simple applications mainly include I2C Hardware connection and I2C Communication protocol Two aspects , This article gives a brief description of common communication methods .
I2C Hardware connection
As shown in the figure below , In a I2C In the communication bus , Can connect multiple I2C Communication equipment , Support multiple communication hosts and multiple communication slaves .
- SDA, SCL Pin and pull-up resistance
- The equipment SDA, SCL Pin use OD Gate output , Line and operate between different equipment , namely “ And logic ”.
- SDA and SCL It needs to be connected with pull resistance , According to I2C Number of equipment , Communication speed of the system , Design and choose different pull-up resistors .I2C The number of devices determines the bus capacitance on the bus , Bus capacitance and pull-up resistance limit the communication rate of the system .
- Usually ,3.3V Pull up the resistance of the system and take 3.3kΩ,5V Pull up the resistance of the system and take 4.7kΩ.
- When I2C When the device is idle , It will output a high resistance state , And when all the devices are idle , When both output high resistance states , Pull the bus to high level by pull-up resistor .
Multi master and multi slave applications
- Each slave device connected to the bus has an independent address , The host can use this address to access different devices .
- When multiple hosts use the bus at the same time , To prevent data conflicts , Arbitration can be used to decide which host device occupies the bus .
I2C Communication protocol
The following figure shows a host (Master) To the slave (Slaver) Write a byte of data as an example , explain I2C Basic protocol of communication .
- Start signal ( S ): When SCL It's high level ,SDA Switch from high level to low level .
- Stop signal ( P ): When SCL It's high level ,SDA Switch from low level to high level .
- Frame address : Unique to each slave 7 Bit or 10 Bit address , Used for address identification between master and slave devices .I2C The protocol states that the device address can be 7 Bit or 10 position , In the actual 7 Bit addresses are widely used .
- read / Write in : a , If the master sends data to the slave, it is low , The request data is high .
- ACK/NACK:I2C The data and address of the transmission are with response . Responses include “ The reply (ACK)” and “ Non response (NACK)” Two signals .ACK Low level ,NACK High level .
- The data is valid : When data is transmitted ,SCL For high voltage ,SDA The data is valid , That at this time SDA Show data for high level “1”, Show data for low level “0”; When SCL Low power level ,SDA Invalid data for , Usually at this time , Yes SDA Carry out level switching .
Focus on v-x- Male - many - Number :【 Embedded base 】
after - platform - return - complex :【 Electric competition 】 Information available
reply 【 Programming 】 Can get
It includes :C、C++、C#、JAVA、Python、JavaScript、PHP、 database 、 Wechat applet 、 Artificial intelligence 、 The embedded 、Linux、Unix、QT、 The Internet of things 、 Introduction to algorithms 、 Big data and other information
边栏推荐
- Codeless June event 2022 codeless Explorer conference will be held soon; AI enhanced codeless tool launched
- 04. 项目博客之日志
- 指针经典笔试题
- 【LeetCode】18、四数之和
- Compilation et connexion de shader dans games202 - webgl (comprendre la direction)
- [QNX Hypervisor 2.2用户手册]6.3.3 使用共享内存(shmem)虚拟设备
- 【torch】|torch. nn. utils. clip_ grad_ norm_
- [mask requirements of OSPF and Isis in multi access network]
- Some common skills on unity inspector are generally used for editor extension or others
- Lepton 无损压缩原理及性能分析
猜你喜欢
05. 博客项目之安全
Codeless June event 2022 codeless Explorer conference will be held soon; AI enhanced codeless tool launched
【torch】|torch.nn.utils.clip_grad_norm_
Idea one key guide package
Modbus协议通信异常
Nacos - TC Construction of High available seata (02)
Vulhub vulnerability recurrence 69_ Tiki Wiki
ByteDance program yuan teaches you how to brush algorithm questions: I'm not afraid of the interviewer tearing the code
First acquaintance with CDN
Imperial cms7.5 imitation "D9 download station" software application download website source code
随机推荐
Self built DNS server, the client opens the web page slowly, the solution
【LeetCode】18、四数之和
First acquaintance with CDN
Vulhub vulnerability recurrence 69_ Tiki Wiki
Vulhub vulnerability recurrence 67_ Supervisor
组播和广播的知识点梳理
Configuration file converted from Excel to Lua
05. 博客项目之安全
UCF (summer team competition II)
Knowledge points of circular structure
Pagoda configuration mongodb
Promotion hung up! The leader said it wasn't my poor skills
02. 开发博客项目之数据存储
Microblogging hot search stock selection strategy
flutter 实现一个有加载动画的按钮(loadingButton)
EditorUtility.SetDirty在Untiy中的作用以及应用
Select knowledge points of structure
Notes, continuation, escape and other symbols
js Array 列表 实战使用总结
Ora-01779: the column corresponding to the non key value saving table cannot be modified