Can not use "SP" variables as a stack pointer

Projects Programming
1

I saw some one use variable name "SP" to print stack pointer.

like

Serial.print(SP)

and when I tried to use it,

I met error message

"SP was not declared in this scope".

I did not use it in any other function, but just in setup() or loop() function.

What did I wrong?

Thank you

2

(deleted)

3

spycatcher2k:
Post your FULL code, as it looks like you did not declare SP.

Yes, I did not declared SP.

What I am confused is,

as far as I know,

SP is reserved symbol for stack pointer.

so I did not need to declare.

SP was not declared should not come out as an error message, because it is already declared in other library file in arduino IDE.

4

mhyem2:
...because it is already declared in other library file in arduino IDE.

If that were true, you would not be getting the error....

Regards,
Ray L.

5

(deleted)

6

SP is defined on AVR boards, not necessarily on others.

Which board are you using?

7

oqibidipo:
SP is defined on AVR boards, not necessarily on others.

Which board are you using?

I am using Arduino Nano 33 BLE

Thank you,

then, is there any way to get stack pointer? like AVR boards?

8

What do you need it for? There may be an easy work-around.

9

If you do need to reference a machine register, use asm()...

10

aarg:
What do you need it for? There may be an easy work-around.

I just want to check stack pointers after function calls..

Thank you for all replies

11

mhyem2:
I just want to check stack pointers after function calls..

Yes, but why?

12

aarg:
Yes, but why?

To check stack region in SRAM of ARM cortex M4 which is a CPU of Arduino Nano 33 BLE?

I thought there must be a reserved region in SRAM for like function prarmeter and return address after procedure call except data and variables. and want to check that region.

13

Yeah, I don't mean to be a pest, but you have again avoided the main question, which is why you want to check that region?