When accessing the System memory area from the Cortex-M4 on the STM32H755, a HardFault occurs.

[JE2]

I'm using a NUCLEO-H755ZI-Q board.

I tried to read following address.

• TEMPSENSOR_CAL1_ADDR (0x1FF1E820UL)
• TEMPSENSOR_CAL2_ADDR (0x1FF1E840UL)

But I can't.

 it causes HardFault interrupt.

I also tried to read the area from Debugger.

Debugger said 

Failed to execute MI command:

-data-evaluate-expression *((short*)0x1FF1E820)

Error message from debugger back end:

Cannot access memory at address 0x1ff1e820

But it is possible from Cortex-M7.

I tried other System Memory area, But I can't.

I think Cortex-M4 cannot access System memory area without special sequence.

How do I access the area form Cortex-M4?

Someone, please help me.

[TDK · Accepted solution]

The 0x1FF00000 area is Reserved on the M4 core and cannot be accessed on the M4 core. It can only be accessed by the M7 core.

[JE2]

Oh! I had overlooked it.

Thanks for your quick reply!