RTOS introduction with Realtek Ameba Board / Arduino SDK

1. RTOS - AMEBA
Neo Jou

2. IOT 技術同好會
Search : Ameba / IoT

3. AMEBA

4. ARM ARCH

5. ARM

6. ARM CORTEX

7. AMEBA CPU
CPU 處理速度
cortem-M3
1.25 DMIPS/MHz
Ameba - 166MHz

8. DAP – DEBUG ACCESS
PORT
Ameba firmware download
UART/Serial to USB
JTAG/SWD debug
Ameba

9. CMSIS-DAP
USB mbed disk / USB-Serial / Debug

10. CMSIS-DAP SETUP
Usb 轉 serial
Driver : ARM mbed serial driver :
https://developer.mbed.org/handbook/Windows-serial-configuration
Usb disk – firmware CMSIS-DAP
DAP Link : https://github.com/mbedmicro/DAPLink
OpenOCD + CMSIS-DAP

11. AMEBA - PROS
相對於⼀般開發板
不⽤另外買 JTAG , 有 ARM CMSIS-DAP debug
有 wifi
Clock ⾼ , 速度快
省電

12. 空氣盒⼦

13. AMEBA

14. TOPICS
⼯商時間
RTOS
Why RTOS
Environment – Arduino / Eclipse – open source
Micro Kernel
memory
schedule
IPC
Future

15. WHY RTOS
Linux v.s. RTOS
Memory
Jitter / response time – audio
Real time
No-OS v.s. RTOS
擴充⽀援 / 多⼯

16. 即時 - REAL TIME
deadline : hard / soft
Linux : RTOS ?
kernel 非搶佔, user 權限⾼也無法搶佔
時間計算/限制機制
改良
重改 linux - PREEMPT_RT
dual kernel - 替換底層 - Xenomai ( 底層⽤ Nucleus )

17. 多⼯-1
真的需要多⼯?
* https://github.com/liuxuming/trochili

18. ARDUINO
setup()
loop()

19. 多⼯-2
ISR
* https://github.com/liuxuming/trochili

20. ARM MBED TICKER
https://developer.mbed.org/handbook/Ticker

21. TIMER CONS
HW timer 有限
SW timer : 延遲
No Preemptive / context switch ?
starvation

22. 多⼯ - 3
multi-tasks

23. 多⼯ - 3
⼯作 Task 程式執⾏最⼩單位?
Process =>Thread
Unix -> Mach
第⼀代 micro kernel
Mac OSX

24. THREAD

25. TOPICS
⼯商時間
RTOS
Why RTOS
Environment – arduino / eclipse
Micro Kernel
memory
schedule
IPC
Future

26. WHY ARDUINO
•
Prototype -> 量產 / ardupilot

27. ARDUINO
http://njiot.blogspot.tw/2016/03/arduino-ameba-100-rtos-1-5100.html
板⼦管理員

28. ARDUINO
http://njiot.blogspot.tw/2016/03/arduino-ameba-100-rtos-1-5100.html
板卡選擇

29. ARDUINO 設定檔
C:
Usersneo_jouAppDataLocalArduino15packagesn
jiothardwareameba1.2.1
Platform.txt
Gcc
Compiler / link options

30. ARDUINO

31. ECLIPSE + QEMU
http://njiot.blogspot.tw/2016/07/qemu-arm-gnu-arm-eclipse.html

32. TOPICS
⼯商時間
RTOS
Why RTOS
Environment – arduino / eclipse
Micro Kernel
memory
schedule
IPC
Future

33. 微核⼼
Memory
Thread
IPC

34. JIM HUANG / JSERV
Embedded system

35. RTOS
https://github.com/neojou/mini-arm-os/tree/master/07-Threads/Threads

36. TOPICS
⼯商時間
RTOS
Why RTOS
Environment – arduino / eclipse
Micro Kernel
memory
schedule
IPC
Future

37. TEXT / DATA
* Howard - HyperC OS
* Linker script -http://njiot.blogspot.tw/2016/03/arduino-ameba-100-textdatabssheapstack.html

38. MEMORY
C: malloc / free
sbrk()
linker script

39. MALLOC

40. RLX8195A
C:
Usersneo_jouAppDataLocalArduino15packagesnjiothardwareameba1.2.1variantsarduino
_amebalinker_scriptsgcc

41. TOPICS
⼯商時間
RTOS
Why RTOS
Environment – arduino / eclipse
Micro Kernel
memory
schedule
IPC
Future

42. REGISTERS

43. AAPCS
Procedure Call Standard for ARM Architecture

44. VECTOR TABLE

45. HANDLER
privileged
thread / handler
handler only have
privileged mode

46. AUTO PUSH / POP
Thread mode -> Handler mode

47. EXC_RETURN
Exception : thread ->
handler
LR : EXC_RETURN

48. ARDUINO SCHEDULER
和 mini-arm-os / RTX 很像
比 timer 優點 :
TCB : Task control block
各⾃有 stack

49. ARDUINO SCHEDULR
NUM_REGS=10, https://github.com/arduino-libraries/Scheduler/blob/master/src/Scheduler.cpp

50. SWITCH- SYSTICK

51. SWITCH - PENDSVC

52. TODO
Thread Priority
Scheduling
Round robin
…

53. 優先權錯逆
priority inversion
realtime - deadline

54. 優先權錯逆
⽕星探測計畫
http://wiki.csie.ncku.edu.tw/embedded/priority-inversion-on-Mars.pdf

55. TOPICS
⼯商時間
RTOS
Why RTOS
Environment – arduino / eclipse
Micro Kernel
memory
schedule
IPC
Future

56. IPC
Inter Process Communication
L4 kernel - 第⼆代微核⼼重點
f9-kernel: http://wiki.csie.ncku.edu.tw/
embedded/f9-kernel

57. L4
http://www.slideshare.net/microkerneldude/from-l3-to-sel4-what-have-we-learnt-in-20-years-l4
https://www.youtube.com/watch?v=RdoaFc5-1Rk

58. RTX ON AMEBA

59. RTX
Keil ARM
CMSIS API
IPC

60. CMSIS-RTOS
Cortex Microcontroller Software Interface Standard

61. SHARE MEMORY
No thread safe
flag
interrupt write status
thread polling

62. CRITICAL SECTION
atomic
spinlock / mutex / semaphore 差異?

63. IPC -⼩訊息傳遞
signal events
mutex
semaphore

64. IPC - ⼤訊息傳遞
message queue
mail queue

65. TOPICS
⼯商時間
RTOS
Why RTOS
Environment – arduino / eclipse
Micro Kernel
memory
schedule
IPC
Future

66. 複雜
drivers
wifi, usb, …
network protocol
TCP/IP
SSL / TLS
MQTT / HTTP
….

67. MBED OS
LoRa : https://docs.mbed.com/docs/lora-with-mbed/en/latest/intro-to-lora/

68. POWER
Tickless kernel
Busy waiting 耗電
WFI / WFE
中斷完成時直接休眠, 不回 Thread, 省下 stack push/pop
Systick or external sleep clock (32K)

69. ZEPHYR 和風
https://www.zephyrproject.org/doc/subsystems/power_management.html

70. 安全
資料安全
資訊隱藏與封裝 (C++)
資訊最⼩化公開原則
各⾃ stack
系統安全 : security boot
網路安全 : SSL/TLS

71. 安全- 硬體設計
Ameba Cortex-M3 :
MPU -> mbed uvisor
hardware crypto engine
加解密, 簽章 : AES / SHA-2
TrustZone : v8m : SAU
stack limit

72. FUTURE
Benchmark
ARM mbed / Arduino
CMSIS++ / mbed minar
NUTTX : ardupilot / cortex-m4
Zephyr : Linux ⼩弟
dynamic linking / module loading
hypervisor

73. THANK YOU
Q & A