Embedded System嵌入式系统

嵌入式系统课程涵盖了从ARM处理器架构、指令集和总线结构到嵌入式开发周期和数据传输与通信的各个方面，内容全面实用。通过本课程的学习，你将掌握嵌入式系统开发的核心技能，包括系统设计、固件开发和任务调度，适用于各种嵌入式应用的开发，是提升工程技术能力的绝佳机会。

Embedded System

• EP_1
  • Refresh
    • Computer architecture
      • types
        • Harvard
        • Von-Neumann
      • components
      • Microprocessors (MPU) vs. Microcontroller (MCU)
    • Bus structure
      • System bus
        • Address bus
        • Control bus
        • Data bus
      • Communications
        • Parallel
        • Serial
          • syncrhonous
          • asynchronous
    • Bitwise operations
      • & AND
      • | OR
      • ^ XOR
      • ~ NOT
  • ARM Processors & interfacing
    • Concept
      • ISA ( Instruction Set Architecture)
      • ARM (Advanced RISC Machine)
        • RISC - Reduced Instruction Set Computer/Computing
        • CISC - Complex Instruction Set Computer/Computing
    • L432KC
      • Memory mapping
      • GPIOs
      • PWM (Pulse Width Modulation)
        • Period
        • Duty cycle
        • Resolution
  • Assemble & Machine Language
    • Elements
      • Mnemonic Operation Codes
        • move (MOV)
        • Arithmetic operation
          • add (ADD)
          • add with carry flag (ADC)
          • substract (SUB)
          • substact with carry flag (SBC)
          • Multiply (MUL)
        • Logical operation
          • AND
          • ORR
          • XOR (EOR)
          • Bit Clear (BIC R6, R1, R2)
            • R2=0, R1不变, R2=1, R1取0
          • MVN
        • Shift
          • Left (LSL)
          • Right (LSR)
        • memory
          • get address (ADR): ADR R4,a
          • load (LDR R1, [R4] / LDR R1, [R4, #4]
          • store (STR)
        • Compare
          • CMP R5, R6
            • perform R5-R6 &set flag
              • =0: Z=1
              • negative: N=1
              • cause carry: C=1
              • cause signed overflow: V=1
        • Condition
          • Condition Flags
            • N: Negative
            • Z: Zero
            • C: Carry
            • V: Overflow
          • Branching
            • B: to another instruction
            • BL:
          • C code: if/else
            • 根据C code,写assembly
              • if 和 flag有关
              • if/else 和 branching
          • 根据assembly,用某些助记符改写assembly
        • Data transfer instruction
          • X = ( A+B ) - C
            • get address: ADR
            • get value: LDR
            • 各种运算
            • get address ADR
            • store STR
      • Operands
        • Registers
        • constant / immediates
      • Data declarations
    • Byte Arrangement
      • Endian
    • The ARM Register File
• EP_2
  • EP Development Circle Tagged
    • Project Development Cycle
      • Requirement Analysis and Specification
      • System Design
      • Prototyping
      • Testing and Verification
      • Deployment and Maintenance
      • Feedback and Iteration
    • Embedded Firmware
      • 2 approaches for the design and implementation firmware
        • Super loop
        • Embedded OS
      • Task Scheduling
        • Considered Factors
          • CPU Utilisation
            • CPU利用率 = (工作时间/总时间) × 100% = xxx%
            • high
          • Throughput ( 吞吐量)
            • 吞吐量 = 完成任务数量 / 总时间 = xxx任务/时间单位
            • maximum
          • Turnaround Time (TAT, 周转时间)
            • Turnaround Time = Completion Time - Arrival Time
            • minimum
          • Waiting Time
            • Waiting time = Turnaround time - Burst time
            • 分段时,和response time 不一样
          • Response Time
            • Response time = Starting time - Arrival time
            • least
        • Type
          • Preemptive
            • 更高级任务可先执行
          • Nonpreemptive
            • 所有任务运行至完成
      • Real Time Management
        • Hard
          • 任务严格在ddl前完成,否则fail
        • Soft
          • 大多数情况需要ddl前完成,偶尔可超时
        • Firm
          • 在大多数情况下可以容忍一些延迟，但在关键时刻必须严格遵守ddl
  • Testing & Debugging
    • Test
      • Type
        • Unit testing
          • 测试单独的软件单元（函数、模块）以验证其正确性和功能
        • Integration testing
          • 测试不同软件模块或组件之间的交互和集成
        • System testing
          • 测试完整的嵌入式系统
        • Acceptance testing
          • 确保系统满足用户需求和期望
        • Regresssion testing
          • 重复以前的测试以确保修改未引入新问题
      • Techniques
        • White Box
          • 关注软件的内部结构和代码实现
        • Black Box
          • 不关注内部代码，仅关注输入和输出
        • Grey Box
          • 既关注外部行为，又涉及部分内部实现,但都不完全
        • Static
          • 分析不执行
          • 有限
        • Dynamic
          • 执行
          • 成本高
    • Task Scheduling
      • Non-preemptive
        • FCFS ( First Come First Service )
        • LCFS / LIFO ( Last In First Out )
        • SJF ( Shortest Job First )
        • Priority based Scheduling
        • Gantt Chart
      • Preemptive
        • SJF ( Shortest Job First )
        • RR ( Round Robin Scheduling )
          • 每个任务被分配一个固定的时间片，在该时间片内任务可以运行。如果任务在时间片结束前未完成，则被暂停，等待下一个轮回​
        • Priority based Scheduling
    • Polling
      • 轮询是一种协议( protocol )，它向CPU指示某个设备需要其注意。这是一个连续的过程，用于检查设备是否正常工作​
    • Interrupt
      • 过程
        • Test interrupts occur (more than one interrupts)
        • Current instruction is stopped
        • Protect the status of current instruction
          • eight registers are pushed on the stack,
        • LR (链接寄存器) is set to 0xFFFFFFF9
        • IPSR (中断服务程序号) is set to the interrupt number,
        • PC is loaded with the interrupt vector
• EP_4
  • DAC
    • Equation
    • Function
      • AnalogOut
      • write
        • output XX.X%
      • write_u16
        • output 0xFF%
      • =
    • DAC-based waveform generation
  • Modular Programming
    • target
      • readable, structured, documented
      • fully and extensively tested
      • reuse existing code
      • multiple engineers working on a single project
      • future upgrades
    • Key Terminologies
      • Modules
      • Interfaces
      • Abstraction
      • Encapsulation
      • Dependencies
    • 优缺点
      • Benefit
        • 代码可复用
        • 易管理
        • 易读
      • Drawback
        • 执行时间开销
        • 嵌套函数使程序复杂
        • 只能返回一个值
    • variable type
      • local variable 局部变量
        • 函数内部
      • formal parameter 形式参数
        • 函数的输入
      • global variable 全局变量
    • Structure
      • Declaration / Prototype
        • 提供函数名、返回类型和参数信息 声明在“.h”文件中
      • Definition
        • 包含函数的实际实现 定义在“.cpp”文件中
    • Process
      • • pre-process
          • 处理 '#' 的指令
            • #include
              • .h文件插入进去
            • 宏 #define
        • compile
          • 编译源文件.c/.cpp->目标文件.o/.obj
        • link
          • 链接所有.o文件->二进制文件.bin
      • 防止被多重声明
        • #ifndef #define ...... #endif
          • if not defined
  • Energy-Efficient EP
    • Hardware
      • MCU
      • peripherals/component
        • type
        • quantity
      • System powering
    • Software
      • run time
      • Algorithms
      • data structure
      • delays, variables, iterations
    • Factors
      • Appllication
      • Process technology
      • Voltage and Frequency
    • Power Consumption 计算
      • • Static (leakage): 待机状态, 设备没有进行任何任务时
        • Dynamic: 设备在运作状态下
        • 单位: mWh等
    • 3 power modes of Mbed OS
      • Active
        • MCU和所有时钟都在运行
      • Sleep
        • core system clock被禁用,
        • 消除 processor/memory systems/buses 的 dynamic power
      • Deep sleep
        • core system clock / high-frequency clocks 被禁用
        • SysTick（系统计时器）也被禁用
      • API
        • void sleep_manager_sleep_auto (void)
        • void sleep_manager_lock_deep_sleep_internal (void)
        • void sleep_manager_unlock_deep_sleep_internal (void)
        • static void sleep (void)
    • 测量mbed 的功率
      • 自带的
      • 用安培表
        • JP1 (IDD)
    • CPU统计睡眠的时间
      • API
        • us_timestamp_t mbed_time_sleep (void)
          • 自启动以来睡眠模式下的时间。
        • us_timestamp_t mbed_time_deepsleep (void)
          • 自启动以来深度睡眠模式下的时间
        • us_timestamp_t mbed_time_idle (void)
          • 自启动以来在空闲模式下的时间
        • us_timestamp_t mbed_uptime (void)
          • 自系统启动以来的时间
• EP_3
  • Lec7
    • ADC
      • function
    • PWM
      • function
    • Interrupt
      • external interrupt
        • InterruptIn
          • InterruptIn button(BUTTON1);
        • ISR
          • void button_isr() { // 中断服务程序 printf("Button pressed!\n"); }
        • 主程序
          • int main() { button.rise(&button_isr); // 在上升沿触发中断 while (true) {} }
      • timeout interrupt
        • Timeout
          • Timeout timeout;
        • ISR
          • void timeout_isr() { // 超时服务程序 printf("Timeout occurred!\n"); }
        • 主程序
          • int main() { timeout.attach(&timeout_isr, 5.0); // 5秒后触发中断 while (true) {} }
      • Timeout+debouncing
        • Timeout+InterruptIn
          • Timeout debounce_timeout; InterruptIn button(BUTTON1);
        • ISR
          • void debounce_isr() { // 去抖动服务程序 printf("Button debounced!\n"); }
          • void button_isr() { debounce_timeout.attach(&debounce_isr, 0.05); // 50毫秒去抖动 }
        • 主程序
          • int main() { button.rise(&button_isr); // 在上升沿触发中断 while (true) {} }
      • Ticker
        • Ticker
          • Ticker ticker;
        • ISR
          • void ticker_isr() { // 定时服务程序 printf("Ticker interrupt!\n"); }
        • 主程序
          • int main() { ticker.attach(&ticker_isr, 2.0); // 每2秒触发一次中断 while (true) {} }
    • Polling
  • I2C Inter-integrated-circuit
    • 简介
      • Synchronous
      • master-slave hierarchy
      • usually 1 master - multiple slaves
      • predefined address for slaves
        • 限制个数
      • Only master can initiate data transmission
    • Structure
      • Serial Data Line (SDA)
        • Bi-directional (one direction at a time – half duplex)
        • data, address, and control
      • Serial Clock Line (SCL)
        • synchronisation
    • Transmission
      • Start & Stop
        • Start: High to Low
        • Stop: Low to High
      • Clock & Data
        • One clock pulse per data bit
        • Data changes when SCL is LOW
        • The first byte : 7 bit address + R/W bit
        • Each byte + 1bit Ack (Acknowlege)
          • 拉低: 确认
          • 未拉低: 错误
          • receiver 发送 Ack, master 失去SDA的控制
    • Function
      • • I2C
        • I2CSlave (slave)
      • • read
        • write
      • frequency
      • start (master)
      • stop
      • receive (slave)
        • check if addressed
      • address (slave)
  • SPI Serial Pheripheral Interface
    • 简介
      • Synchronous
      • master slave hierarchy
      • onyl master initiate data transmission
    • Structure
      • Serial Data In (SDI)
      • Serial Data Out (SDO)
      • full duplex
      • Serial Clock (SCK)
      • Slave Select (SS) Chip Select (CS)
        • =0: 开始通信
    • Functions
      • master
        • SPI
        • format
        • frequency
        • write
        • set_default_write_value
      • slave
        • SPISlave
        • format
        • frequency
        • receive
        • read
        • reply
  • SPI vs I2C
    • SPI - Advantages
      • Full-duplex communication
      • Speed – I2C: 5 Mbps / SPI: >=10 Mbps
      • Not limited to 8-bit words
      • Lower power requirements
    • I2C - Advantages
      • Simple – Implements a 2-wire interface unlike SPI
      • Multiple slave devices without using extra pins
      • Flexibility - Supports multiple Masters