Programming Embedded System in C and C

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Programming Embedded System in C and C

• What is Embedded System?
• ????????????,???????????????????????,??????????.
• ?? ABS,???,PS,PDA,??,???.

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C????

• C???
• ????????.
• ??????????.
• ???????????.
• C??? ??C???
• ?????????????.
• ?????????????????

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??????????

???
???
??
??
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Hello World too Hard

• P2LTCH Port2 I/O Latch Register
• ?CPU?????,?????
• ????I/O pin?latch??.

Intel 80188EB ?????? P2LTCH0100 0000
Intel 80188EB ?????? P2LTCH0000 0000
??LED
??LED
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???????????

C/C
C/C
??
compiler
assembler
compiler
Object code
Object code
Object code
Linker
Relocation code
???
????
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???????????
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Reset Reset Code (in assembly) Jmp hw_init
Startup Startup Code (in assembly) Call main
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Hw_init Hardware Initialization (in
assembly) Jmp startup
Main() /the C/C code Start here /

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4
7
??????

???
RAM
???
ROM
DRAM
SRAM
EPROM
Masked
Flash
NVRAM
PROM
EEPROM
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?????

• Data bus test
• Address bus test
• Chip test

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??

• On-chip peripheral ????????????????????.
• External peripheral????????????

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Device Driver?????

• Device driver????????????????.
• ????????????????????.
• ?????????????????????,
• ????????,?ISR??????????
• ?.

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???????????

• ???????????????????.
• ?????????memory-mapped peripheral?I/O mapped
  peripheral.
• Memory-mapped peripheral????.
• volatile unsigned short pP2LTCH(unsigned
  short) 0x7200005E
• void toggleLed(void)
• pP2LTCH LED_GREEN // read,XOR,set

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????

• ????????????,?????????.
• ????????,???????????.
• ??ADEOS(A Decent Embeded OS)
• ??????1000?,??????????????,????C??,??????????
  ???????,?????.

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Task

• ???????????????Task,???????Task????????CPU.

??? (Running)
?? (Ready)
??? (Waiting)
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Scheduler

• ????????????????Task,??????Task???????.? FIFO ,
  Shorest First , Round Robin ?.
• ?????????Priority-based????,?????scheduling
  point.
• Scheduling point?scheduler????Task?????????.
• scheduling point?????task???task?
• clock tick.

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Context Switch

• ???Task??????Task???
• ???????????????,?????
• ??????????.

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Task Synchronization

• ??Mutex?????task??????,
• ?????Mutex?????????.

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????

Hello Word Task
????LED?Task
LED Driver
Timer Driver
??? Driver
ADEDS OS
??
????
??