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hi i use the code below to store a value in memory address 0xfffff400,but when i debug ,it sotored reverse in memory address 0xfffff408
AREA CODE,CODE,READonly
ENTRY
LDR R1,=0XAA0AA0FF LDR R5,=0xfffff400 STR R1,[R5]
END
Interesting observation. Faulty hardware? Incorrect connection between CPU and external memory? Bad bus timing?
i use internal memory,i want access pio register,can u tell me for writin assembly is any thing i must write befor my program?i mean any initializing?
I am not a native English speaker either. But please, the language deserves more respect. As to the question, it would help if you stated the part number of the MCU you are using.
i use at91sam7x256 please show me a reall assembly example if you could tank u
It's time to read the user manual of AT91SAM7X256.
The address 0xFFFFF400 belongs to PIOA PIO_PER which is a write only register (PIO Enable Register) and directly affects the PIO_PSR (PIO Status Register) at address 0xFFFFF408.
So writing to location at 0xFFFFF400 (PIO_PER) can change the values at 0xFFFFF408 (PIO_PSR) and reading back 0xFFFFF400 (PIO_PER) is unpredictable.
tnanx for ur assisst