Stack placed in RAM2

[markvanderheijd]

My stack is placed at location 0x20080000 on my LPC1766. Thats AHB SRAM - bank 1. I like to have my stack on the On-chip SRAM(0x10000000). my linker script is defined like this:

PROVIDE(_pvHeapStart = DEFINED(__user_heap_base) ? __user_heap_base : .);
PROVIDE(_vStackTop = DEFINED(__user_stack_top) ? __user_stack_top : __top_RamLoc32 - 0);

What can be the reason that it still writing in RAM2(bank1)?

[markvanderheijd]

Thank you for your reaction, 

I hope you can explain me something.

when i execute this code:

uint8_t test;

printf("test addr %x\r\n",&test);

my debug output says:
test addr 20083fe7

So my thought was that [test] is placed on the stack and with asking the adders of [test] i can figure out where the stack is placed.

my current problem is that the initialization of local variable goes wrong.

void SCR_idle(void){
   Point_t point1 = {.x=120,.y=30}; 

..etc

after executing Point_t point1 = {.x=120,.y=30};  the value of point.x ==0 and point.y == 0.
when i was searching for the problem i found out with printing the location of the variables that its on a different location.

I though that my  memory was build up like:

On-chip SRAM-bottom:

-vtable
-bss

-data

-heap

On-chip SRAM-top:

-stack

RAM2

-bss (large buffers defined by   __BSS(RAM2))

whats wrong with my interpretation?

thank you in advance!

[jeremyzhou]

Hi mark van der Heijden,

Thanks for your reply and I'd like to confirm something wih you.

Whether test is the global value.
Have a great day,
TIC

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[markvanderheijd]

Hi Jeremyzhou,

Thank you for your reaction.

The variables are local variables.

I moved more buffers to RAM2 and now my code seems to work. But i still don't understand whats happening.
two things are unclear for me.

1. my previous question : wy the  function :
void SCR_idle(void){
   Point_t point1 = {.x=120,.y=30}; 

   printf("debug addr: %x", &point1 )

}

printout a location in the RAM2 segment.

2.in my startup file i write my whole memory(On-chip SRAM) with a pattern 

unsigned int addr;
for(addr = 0x10000000; addr < 0x10007DFF; addr++){
if(addr %2){
*(unsigned int *)addr = 0xde;
}else{
*(unsigned int *)addr = 0xad;
}
}

after the failing initialization of a local variable i checked my memory and i see a lot of DEADDE still in my memory. Wat can be the reason that the initialization is failing.

thank you in advance!

[jeremyzhou]

Hi mark van der Heijden,

The question seems a bit interesting, and I will appreciate if you share the completely testing code.

I'm looking forward to your reply.
Have a great day,
TIC

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