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MicroC/OS-II

MicroC/OS-II. Chia-Tai Tsai tai@cis.nctu.edu.tw. Feature. Source Code Open Source ，程式碼簡潔易懂 Portable 程式碼大部分皆是利用 ANSI C 所開發的 與 microprocessor 行為有關的則利用組合語言來完成，使得 uC/OS-II 能夠輕易的移植到其他 Processor uC/OS-II 可以在 8/16/32 bits 的 microprocessor 上或是 micro-controller 上運作. Feature. ROMable

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MicroC/OS-II

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  1. MicroC/OS-II Chia-Tai Tsai tai@cis.nctu.edu.tw

  2. Feature • Source Code • Open Source，程式碼簡潔易懂 • Portable • 程式碼大部分皆是利用ANSI C所開發的 • 與microprocessor行為有關的則利用組合語言來完成，使得uC/OS-II能夠輕易的移植到其他Processor • uC/OS-II可以在8/16/32 bits的microprocessor上或是micro-controller上運作

  3. Feature • ROMable • 只要有適當的工具(C compiler, assembler and linker/locator)就可以將uC/OS-II嵌入成為產品一部分 • Scalable • 可以很簡單的選用程式/產品所需要的特性 • 也就是說可以依照自己的需求減少程式的大小，以便可以放入ROM/RAM中

  4. TASK WAITING TASK DORMANT TASK READY TASK RUNNING ISR RUNNING

  5. Feature • Preemptive • uC/OS-II 永遠會讓已經Ready且優先權最高的工作行程先執行 • Multi-tasking • uC/OS-II最多可支援64個task，其中會為系統保留8個task使用 • 每一個task都有一個唯一的priority，也就是說uC/OS-II無法實現Round Robin排程

  6. TASK #n Stack TASK #1 Stack TASK #2 Stack Task Control Block Task Control Block Task Control Block Status Status Status SP SP SP Priority Priority Priority . . . . . . . . . SP . . . …… MEMORY CPU

  7. LOW Priority Task ISR (1) (2) HIGH Priority Task (4) (3) Time ISR makes the high priority task ready (5) (6) (7)

  8. Feature • Deterministic • 在uC/OS-II內的各項服務所需要的執行時間都是可明確預先得知的 • Task Stacks • uC/OS-II允許每一個task擁有不一樣的stack size • 根據需要增減task的stack size減少RAM的使用

  9. Feature • Services • Mailbox, Queues, Semaphores, Fixed-sized memory partitions, Time related function, etc. • Interrupt Management • Interrupts can suspend the execution of a task • 255 levels • Robust and Reliable

  10. uC/OS-II移植分析 • 只要有相對應的C Compiler，即可將uC/OS-II移植到特定的處理器上 • 大部分移植工作都在多任務的切換上 • 用來儲存以及恢復register的值 • 利用組合語言完成 • 需修改的檔案 • OS_CPU.H, OS_CPU_C.C, OS_CPU_A.S

  11. OS_CPU.H • 定義DATA TYPE • 與所使用的Compiler相關 • 不同的Compiler會使用不一樣的byte來表示同一DATA TYPE • X86平台, Integer: • GNU (gcc): 4 bytes • M$ (VC++): 2 bytes

  12. OS_CPU.H • Stack Entry • 定義TASK的Stack長度，必須要和CPU的Resgister的長度一致 • 堆疊增長方向 • 定義Stack grows from HIGH to LOW or Low to HIGH Memory

  13. OS_CPU.H

  14. OS_CPU.H • 中斷、Content Switch

  15. AX CX DX BX SP BP SI DI ES DS OS_CPU_C.C HIGH • Initialize a Task‘s STACK • 在堆疊增長的方向上定每一個需要保存的Register位址 LOW

  16. OS_CPU_C.C

  17. OS_CPU_A.S • OSStartHighRdy( ) • 在OSStart()啟動之後，負責從最高優先權任務的TCB Control Block中獲得該任務的Stack Point(SP) • OSCtxSw( ) • 將前一task的register保存到堆疊中，獲得最高優先權task的SP，將此task的register恢復，使之繼續執行

  18. OS_CPU_A.S • OSIntCtxSw( ) • 中斷級的Content Switch

  19. lwIP簡介 • 一套用於embedded system的TCP/IP • lwIP可以移植到各OS上，在沒有OS情形下也可以獨立運作 • lwIP主要是為了保持TCP Protocol的主要功能並減少對RAM的使用 • 只需要幾十K的RAM和約40K的ROM就可以運作，使得lwIP很適合在嵌入式系統中運作

  20. ULP lwIP Protocol uC/OS-II Network Driver Embedded System系統開發板 NE2000 lwIP簡介

  21. lwIP特性 • IP including packet forwarding over multiple network interfaces • ICMP for network maintenance and debugging • UDP for datagram data • TCP with congestion control, RTT estimation and fast recovery/fast retransmit • Specialized no-copy API for enhanced performance • Optional Berkeley socket API

  22. lwIP將所有與硬體、OS、Compiler相關的部分獨立出來放置在/src/arch下lwIP將所有與硬體、OS、Compiler相關的部分獨立出來放置在/src/arch下 • 修改這一些相關檔案將lwIP移植到uC/OS-II上

  23. eth_addr eth_hdr ip_addr ip_hdr pbuf tcp_hdr tcp_pcb tcp_seq udp_hdr udp_pcb lwIP Data Structure

  24. lwIP Data Structure • eth_addr • The structure of one MAC address • eth_hdr • eth_addr dest • eth_addr src eth_addr eth_hdr

  25. lwIP Data Structure • ip_addr • The structure of a IP address in network byte order • ip_hdr ip_addr ip_hdr

  26. lwIP Data Structure • pbuf • The header structure of packet buffers • A pbuf is lwIP’s internal representation of a packet • Designed for the special needs of the minimal stack • similar to the mbuf used in the BSD implementations

  27. lwIP Data Structure • Allocating dynamic memory to hold packet contents • Letting packet data reside in static memory • Pbufs can be linked together in a list

  28. lwIP Data Structure • tcp_hdr • The header of a TCP packet • tcp_pcb • The protocol control block for TCP connections • contains any information for one TCP connection

  29. lwIP Data Structure • The TCP PCBs are kept on a linked list which is searched for a match when a TCP packet arrives • TCP PCB structures contain a pointer to the next PCB in the global linked list of TCP PCBs

  30. lwIP Data Structure • tcp_seq • This structure is used to represent TCP segments when queued

  31. lwIP Data Structure • udp_hdr • the header of a UDP packet • udp_pcb • The protocol control block for UDP connections • contains any information for one UDP connection

  32. lwIP Data Structure • UDP PCBs are kept on a linked list which is searched for a match when a UDP datagram arrives • UDP PCB structures contain a pointer to the next PCB in the global linked list of UDP PCBs

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